Publisher：Physical Review C  

The shell closure at N=32 has been investigated by a first spectroscopy of the N=31 nucleus Ar49 at the Radioactive Isotope Beam Factory. Using the Ar50(p,pn) reaction channel in inverse kinematics, Ar50 projectiles at 217 MeV/nucleon impinged on a 150 mm long liquid hydrogen target, part of the MINOS device. Prompt deexcitation γ rays were measured with the NaI(Tl) array DALI2+. Reaction products were analyzed with the SAMURAI spectrometer, which allowed the measurement of the momentum distributions and angular momentum transfer. Data were compared to state-of-the-art theoretical predictions, including shell-model, energy-density functional, and ab initio calculations. An onset of collectivity is suggested besides the spherical configuration typical of a closed shell nucleus, such as for Ca52.

DOI： 10.1103/PhysRevC.109.034312

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Physical Society (APS)  

The cluster structure of the neutron-rich isotope 10Be has been probed via the (p,pα) reaction at 150 MeV/nucleon in inverse kinematics and in quasifree conditions. The populated states of 6He residues were investigated through missing mass spectroscopy. The triple differential cross section for the ground-state transition was extracted for quasifree angle pairs (θp,θα) and compared to distorted-wave impulse approximation reaction calculations performed in a microscopic framework using successively the Tohsaki-Horiuchi-Schuck-Röpke product wave function and the wave function deduced from antisymmetrized molecular dynamics calculations. The remarkable agreement between calculated and measured cross sections in both shape and magnitude validates the molecular structure description of the 10Be ground-state, configured as an α−α core with two valence neutrons occupying π-type molecular orbitals.

DOI： 10.1103/physrevlett.131.212501

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：American Physical Society (APS)  

Background: The description of deuteron-induced inclusive reactions has been an important subject in direct nuclear reaction studies and nuclear data science. For proton-induced inclusive processes, the semiclassical distorted wave model (SCDW) is one of the most successful models based on quantum mechanics. Purpose: We improve SCDW for deuteron-induced inclusive processes and clarify the importance of the proper treatment of the kinematics of the deuteron inside a nucleus. Methods: The double differential cross section (DDX) of the inclusive deuteron-emission process (d,d′x) is described by one-step SCDW. The changes in the kinematics due to the distortion effect, the refraction effect, are taken into account by the local semiclassical approximation. Results: The calculated DDXs of (d,d′x) reasonably reproduce experimental data in the small energy-transfer region and at forward and middle angles with some exceptions. The angular distributions of (d,d′x) are improved by including the refraction effect. Conclusion: The proper treatment of the changes in the kinematics of the deuteron inside a nucleus is necessary in describing the (d,d′x) reaction. The effect of the changes on the DDX of (d,d′x) is significant compared to on the proton-induced inclusive process (p,p′x) because of the stronger distortion effect on the deuteron.

DOI： 10.1103/physrevc.108.034603

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：Physical Society of Japan  

Recent studies on nucleon and alpha knockout reactions have shown that the distorted-wave impulse approximation (DWIA) is a simple and accurate method to describe these reactions. As it has been argued for decades, the nuclear absorption is one of the most important ingredients of the DWIA calculation. In this work, we systematically investigate the absorption effects on the cross sections of the nucleon and alpha knockout reactions. To do this, we calculate the ratio of the cross sections of the DWIA and plane-wave impulse approximation (PWIA) and examine its dependence on the mass number and single-particle orbital of the knocked-out particles. We will discuss the specific characteristics of the absorption effect for each reaction.

DOI： 10.7566/jpsj.92.094201

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Detailed γ-ray spectroscopy of the exotic neon isotope 28Ne has been performed for the first time using the one-neutron removal reaction from 29Ne on a liquid hydrogen target at 240 MeV/nucleon. Based on an analysis of parallel momentum distributions, a level scheme with spin-parity assignments has been constructed for 28Ne and the negative-parity states are identified for the first time. The measured partial cross sections and momentum distributions reveal a significant intruder p-wave strength providing evidence of the breakdown of the N=20 and N=28 shell gaps. Only a weak, possible f-wave strength was observed to bound final states. Large-scale shell-model calculations with different effective interactions do not reproduce the large p-wave and small f-wave strength observed experimentally, indicating an ongoing challenge for a complete theoretical description of the transition into the island of inversion along the Ne isotopic chain.

DOI： 10.1016/j.physletb.2023.138038

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Abstract

Subjecting a physical system to extreme conditions is one of the means often used to obtain a better understanding and deeper insight into its organization and structure. In the case of the atomic nucleus, one such approach is to investigate isotopes that have very different neutron-to-proton (N/Z) ratios than in stable nuclei. Light, neutron-rich isotopes exhibit the most asymmetric N/Z ratios and those lying beyond the limits of binding, which undergo spontaneous neutron emission and exist only as very short-lived resonances (about 10⁻²¹ s), provide the most stringent tests of modern nuclear-structure theories. Here we report on the first observation of ²⁸O and ²⁷O through their decay into ²⁴O and four and three neutrons, respectively. The ²⁸O nucleus is of particular interest as, with the Z = 8 and N = 20 magic numbers^1,2, it is expected in the standard shell-model picture of nuclear structure to be one of a relatively small number of so-called ‘doubly magic’ nuclei. Both ²⁷O and ²⁸O were found to exist as narrow, low-lying resonances and their decay energies are compared here to the results of sophisticated theoretical modelling, including a large-scale shell-model calculation and a newly developed statistical approach. In both cases, the underlying nuclear interactions were derived from effective field theories of quantum chromodynamics. Finally, it is shown that the cross-section for the production of ²⁸O from a ²⁹F beam is consistent with it not exhibiting a closed N = 20 shell structure.

DOI： 10.1038/s41586-023-06352-6

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：American Physical Society (APS)  

Background: Systematic measurement of t and 3He knockout processes is planned. The weakly-bound nature of these nuclei may affect the interpretation of forthcoming knockout reaction data. Purpose: We aim at clarifying breakup properties of t and 3He by investigating their elastic and breakup cross sections. Methods: We employ the four-body continuum-discretized coupled-channels method with the eikonal approximation to describe the reactions with t and 3He projectiles. Results: The breakup cross section of t is found to be almost the same as that of 3He and is about one-third of that of d. Coulomb breakup plays negligible role in the breakup of t and 3He, in contrast to in the deuteron breakup reaction. It is found that t and 3He tend to break up into three nucleons rather than d and a nucleon. Conclusions: It is shown that the breakup cross sections of t and 3He are not as large as those of d but nonnegligible. Because about 80% of them corresponds to the three-nucleon breakup process, a four-body breakup reaction model is necessary to quantitatively describe the breakup of t and 3He.

DOI： 10.1103/physrevc.108.024604

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

Gamma decays were observed in 56Ca and 58Ca following quasi-free one-proton knockout reactions from 57,59Sc beams at ≈200 MeV/nucleon. For 56Ca, a γ ray transition was measured to be 1456(12) keV, while for 58Ca an indication for a transition was observed at 1115(34) keV. Both transitions were tentatively assigned as the 21+→0gs+ decays, and were compared to results from ab initio and conventional shell-model approaches. A shell-model calculation in a wide model space with a marginally modified effective nucleon-nucleon interaction depicts excellent agreement with experiment for 21+ level energies, two-neutron separation energies, and reaction cross sections, corroborating the formation of a new nuclear shell above the N = 34 shell. Its constituents, the 0f5/2 and 0g9/2 orbitals, are almost degenerate. This degeneracy precludes the possibility for a doubly magic 60Ca and potentially drives the dripline of Ca isotopes to 70Ca or even beyond.

DOI： 10.1016/j.physletb.2023.138025

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Effective polarization in proton-induced α knockout reactions

DOI： 10.1103/physrevc.107.054603

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We report on the first proton-induced single proton- and neutron-removal reactions from the neutron-deficient 14O nucleus with large Fermi-surface asymmetry Sn−Sp=18.6 MeV at 100 MeV/nucleon, a widely used energy regime for rare-isotope studies. The measured inclusive cross sections and parallel momentum distributions of the 13N and 13O residues are compared to the state-of-the-art reaction models, with nuclear structure inputs from many-body shell-model calculations. Our results provide the first quantitative contributions of multiple reaction mechanisms including the quasifree knockout, inelastic scattering, and nucleon transfer processes. It is shown that the inelastic scattering and nucleon transfer, usually neglected at such energy regime, contribute about 50% and 30% to the loosely bound proton and deeply bound neutron removal, respectively. These multiple reaction mechanisms should be considered in analyses of inclusive one-nucleon removal cross sections measured at intermediate energies for quantitative investigation of single-particle strengths and correlations in atomic nuclei.

DOI： 10.1103/physrevlett.130.172501

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Extended p3/2 Neutron Orbital and the N = 32 Shell Closure in 52Ca

DOI： 10.1103/physrevlett.129.262501

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“Southwestern” boundary of the N = 40 island of inversion: First study of low-lying bound excited states in 59V and 61V

DOI： 10.1103/physrevc.106.064321

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Background: An isoscalar pn pair is expected to emerge in nuclei that have similar proton and neutron numbers and it may be a candidate for a deuteron "cluster."There is, however, no experimental evidence for it. Purpose: The purpose of this paper is to construct a new reaction model for the (p,pd) reaction including the deuteron breakup in the elementary process and the deuteron reformation by the final-state interactions. How these processes contribute to the observables of the reaction is investigated. Methods: The distorted wave impulse approximation is extended twofold. The elementary processes of the (p,pd), i.e., the p-d elastic scattering and the d(p,p)pn reaction, are described with an impulse picture employing a nucleon-nucleon effective interaction. The three-body scattering waves in the final state of the (p,pd) reaction are calculated with the continuum-discretized coupled-channels method. The triple-differential cross section (TDX) of the (p,pd) reaction is calculated with the new model. Results: The elementary processes are described reasonably well with the present model. As for the (p,pd) reaction, the deuteron reformation can either increase or decrease the TDX height depending on the interference between the elastic and breakup channels of deuteron, while the back-coupling effect always decreases it. Conclusions: It is shown that the deuteron reformation significantly changes the TDX of the (p,pd) reaction through the interference. It is important to include this process to quantitatively discuss the (p,pd) cross sections in view of the deuteron formation in nuclei. For more quantitative discussion regarding the experimental data, further improvement will be necessary.

DOI： 10.1103/physrevc.106.064613

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Publisher：Progress in Particle and Nuclear Physics  

Atomic nuclei are composite systems, and they may be dynamically excited during nuclear reactions. Such excitations are not only relevant to inelastic scattering but they also affect other reaction processes such as elastic scattering and fusion. The coupled-channels approach is a framework which can describe these reaction processes in a unified manner. It expands the total wave function of the system in terms of the ground and excited states of the colliding nuclei, and solves the coupled Schrödinger equations to obtain the S-matrix, from which several cross sections can be constructed. This approach has been a standard tool to analyze experimental data for nuclear reactions. In this paper, we review the present status and the recent developments of the coupled-channels approach. This includes the microscopic coupled-channels method and its application to cluster physics, the continuum discretized coupled-channels (CDCC) method for breakup reactions, the semi-microscopic approach to heavy-ion subbarrier fusion reactions, the channel coupling effects on nuclear astrophysics and syntheses of superheavy elements, and inclusive breakup and incomplete fusion reactions of weakly-bound nuclei.

DOI： 10.1016/j.ppnp.2022.103951

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Publishing type：Research paper (international conference proceedings)  

The correlation functions of pΞ− and ΛΛ pairs from pp and pA collisions are studied in the coupled-channel framework using the NΞ-ΛΛ coupled-channel baryon-baryon potentials obtained in the lattice QCD calculation at almost physical quark masses. The pΞ− correlation function is calculated to be significantly enhanced from the pure Coulomb case, while the ΛΛ correlation function is slightly enhanced from that of the pure fermion quantum statistics. These features reflect the large and small scattering lengths in the pΞ− and ΛΛ channels in magnitude, and agree with the observed data by the ALICE collaboration. The agreement confirms the S = −2 baryon-baryon potentials from lattice QCD.

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Publisher：Proceedings of Science  

The correlation functions of pΞ− and ΛΛ pairs from pp and pA collisions are studied in the coupled-channel framework using the NΞ-ΛΛ coupled-channel baryon-baryon potentials obtained in the lattice QCD calculation at almost physical quark masses. The pΞ− correlation function is calculated to be significantly enhanced from the pure Coulomb case, while the ΛΛ correlation function is slightly enhanced from that of the pure fermion quantum statistics. These features reflect the large and small scattering lengths in the pΞ− and ΛΛ channels in magnitude, and agree with the observed data by the ALICE collaboration. The agreement confirms the S = −2 baryon-baryon potentials from lattice QCD.

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Language：Others   Publishing type：Research paper (other academic)  

The correlation functions of pΞ− and ΛΛ pairs from pp and pA collisions are studied in the coupled-channel framework using the NΞ-ΛΛ coupled-channel baryon-baryon potentials obtained in the lattice QCD calculation at almost physical quark masses. The pΞ− correlation function is calculated to be significantly enhanced from the pure Coulomb case, while the ΛΛ correlation function is slightly enhanced from that of the pure fermion quantum statistics. These features reflect the large and small scattering lengths in the pΞ− and ΛΛ channels in magnitude, and agree with the observed data by the ALICE collaboration. The agreement confirms the S = −2 baryon-baryon potentials from lattice QCD.

Language：Others   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

States in the N=35 and 37 isotopes 55,57Ca have been populated by direct proton-induced nucleon removal reactions from 56,58Sc and 56Ca beams at the RIBF. In addition, the (p,2p) quasi-free single-proton removal reaction from 56Ca was studied. Excited states in 55K, 55Ca, and 57Ca were established for the first time via in-beam γ-ray spectroscopy. Results for the proton and neutron removal reactions from 56Ca to states in 55K and 55Ca for the level energies, excited state lifetimes, and exclusive cross sections agree well with state-of-the-art theoretical calculations using different approaches. The observation of a short-lived state in 57Ca suggests a transition in the calcium isotopic chain from single-particle dominated states at N=35 to collective excitations at N=37.

DOI： 10.1016/j.physletb.2022.136953

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Publisher：Few-Body Systems  

Intensive neutron sources using deuteron accelerators have been proposed not only in science but also in engineering and medical fields. For the design study of such facilities, accurate and comprehensive nuclear database for deuteron-induced reactions are indispensable. Due to the limited experimental data, theoretical model calculations play key roles in the development of nuclear database. Under these circumstances, we have been developing a code system for deuteron-induced reactions, called the DEUteron-induced Reaction Analysis Code System (DEURACS). In this paper, we present some analysis results of experimental data using DEURACS in terms with (d, xn), (d, xp), and (d, xd) reactions that are important in deuteron transport simulation for the design study of the accelerator-based neutron sources.

DOI： 10.1007/s00601-021-01712-2

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The momentum correlation functions of S=-2 baryon pairs (pΞ- and ΛΛ) produced in high-energy pp and pA collisions are investigated on the basis of the coupled-channels formalism. The strong interaction is described by the coupled-channels HAL QCD potential obtained by lattice QCD simulations near physical quark masses, while the hadronic source function is taken to be a static Gaussian form. The coupled-channels effect, the threshold difference, the realistic strong interaction, and the Coulomb interaction are fully taken into account for the first time in the femtoscopic analysis of baryon-baryon correlations. The characteristic features of the experimental data for the pΞ- and ΛΛ pairs at the Large Hadron Collider are reproduced quantitatively with a suitable choice of nonfemtoscopic parameters and the source size. The agreement between theory and experiment indicates that the NΞ (ΛΛ) interaction is moderately (weakly) attractive without having a quasibound (bound) state.

DOI： 10.1103/physrevc.105.014915

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Background: Both (e,e′p) and (p,2p) reactions have been performed to study the proton single-particle character of nuclear states with its related spectroscopic factor. Recently, the dispersive optical model (DOM) was applied to the (e,e′p) analysis revealing that the traditional treatment of the single-particle overlap function, distorted waves, and nonlocality must be further improved to achieve quantitative nuclear spectroscopy. Purpose: We apply the DOM wave functions to the traditional (p,2p) analysis and investigate the consistency of the DOM spectroscopic factor that describes the (e,e′p) cross section with the result of the (p,2p) analysis. Additionally, we make a comparison with a phenomenological single-particle wave function and optical potential. Uncertainty arising from a choice of p-p interaction is also investigated. Method: We implement the DOM wave functions to the nonrelativistic distorted-wave impulse approximation (DWIA) framework for (p,2p) reactions. Results: DOM + DWIA analysis on Ca40(p,2p)K39 data generates a proton 0d3/2 spectroscopic factor of 0.560, which is meaningfully smaller than the DOM value of 0.71 shown to be consistent with the (e,e′p) analysis. Uncertainties arising from choices of single-particle wave function, optical potential, and p-p interaction do not explain this inconsistency. Conclusions: The inconsistency in the spectroscopic factor suggests there is urgent need for improving the description of p-p scattering in a nucleus and the resulting in-medium interaction with corresponding implications for the analysis of this reaction in inverse kinematics.

DOI： 10.1103/physrevc.105.014622

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<title>Abstract</title>
The correspondence between the isoscalar monopole (IS0) transition strengths and $alpha$ inelastic cross sections, the $B({
m IS0})$–$(alpha,alpha')$ correspondence, is investigated for $^{24}$Mg($alpha,alpha'$) at 130 and 386 MeV. We adopt a microscopic coupled-channel reaction framework to link structural inputs, diagonal and transition densities, for $^{24}$Mg obtained with antisymmetrized molecular dynamics to the ($alpha,alpha'$) cross sections. We aim at clarifying how the $B({
m IS0})$–$(alpha,alpha')$ correspondence is affected by the nuclear distortion, the in-medium modification to the nucleon–nucleon effective interaction in the scattering process, and the coupled-channel effect. It is found that these effects are significant and the explanation of the $B({
m IS0})$–$(alpha,alpha')$ correspondence in the plane wave limit with the long-wavelength approximation, which is often used, makes no sense. Nevertheless, the $B({
m IS0})$–$(alpha,alpha')$ correspondence tends to remain because of a strong constraint on the transition densities between the ground state and the $0^+$ excited states. The correspondence is found to hold at 386 MeV with an error of about 20%–30%, while it is seriously compromised at 130 MeV, mainly by the strong nuclear distortion. It is also found that when a $0^+$ state that has a different structure from a simple $alpha$ cluster state is considered, the $B({
m IS0})$–$(alpha,alpha')$ correspondence becomes less valid. For a quantitative discussion on the $alpha$ clustering in $0^+$ excited states of nuclei, a microscopic description of both the structure and reaction parts will be necessary.

DOI： 10.1093/ptep/ptab112

Language：English   Publishing type：Research paper (scientific journal)  

A first gamma-ray study of Cl-47,Cl-49 spectroscopy was performed at the Radioactive Isotope Beam Factory with 50 Ar projectiles at 217 MeV/nucleon, impinging on the liquid hydrogen target of the MINOS device. Prompt deexcitation gamma rays were measured with the NaI(T1) array DALI2(+). Through the one-proton knockout reaction Ar-50(p, 2p), a spin assignment could be determined for the low-lying states of Cl-49 from the momentum distribution obtained with the SAMURAI spectrometer. A spin-parity J(pi) = 3/2(+) is deduced for the ground state of Cl-49, similar to the recently studied N = 32 isotope K-51. The evolution of the energy difference E(1/2(1)(+)) - E (3/2(1)(+)) is compared to state-of-the-art theoretical predictions.

DOI： 10.1103/physrevc.104.044331

Language：Others   Publishing type：Research paper (scientific journal)  

DOI： 10.1103/physrevc.104.044608

Language：Others   Publishing type：Research paper (scientific journal)  

Background: The C9 nucleus and related capture reaction, B8(p,γ)C9, have been intensively studied with an astrophysical interest. Due to the weakly bound nature of C9, its structure is likely to be described as the three-body (Be7+p+p). Its continuum structure is also important to describe reaction processes of C9, with which the reaction rate of the B8(p,γ)C9 process have been extracted indirectly. Purpose: We preform three-body calculations on C9 and discuss properties of its ground and low-lying states via breakup reactions. Methods: We employ the three-body model of C9 using the Gaussian-expansion method combined with the complex-scaling method. This model is implemented in the four-body version of the continuum-discretized coupled-channels method, by which breakup reactions of C9 are studied. The intrinsic spin of Be7 is disregarded. Results: By tuning a three-body interaction in the Hamiltonian of C9, we obtain the low-lying 2+ state with the resonant energy 0.781 MeV and the decay width 0.137 MeV, which is consistent with the available experimental information and a relatively high-lying second 2+ wider resonant state. Our calculation predicts also sole 0+ and three 1- resonant states. We discuss the role of these resonances in the elastic breakup cross section of C9 on Pb208 at 65 and 160 MeV/nucleon. Conclusions: The low-lying 2+ state is probed as a sharp peak of the breakup cross section, while the 1- states enhance the cross section around 3 MeV. Our calculations will further support the future and ongoing experimental campaigns for extracting astrophysical information and evaluating the two-proton removal cross sections.

DOI： 10.1103/physrevc.104.034612

Language：Others   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.physletb.2021.136466

Language：Others   Publishing type：Research paper (scientific journal)  

Background: The hadron-deuteron correlation function has attracted much interest as a potential method to access three-hadron interactions. However, the weakly bound nature of deuterons has not been considered in the preceding studies. Purpose: The breakup effect of deuterons in the deuteron-Ξ- (d-Ξ-) correlation function CdΞ- is investigated. Methods: The d-Ξ- scattering is described by a nucleon-nucleon-Ξ three-body reaction model. The continuum-discretized coupled-channels method, which is a fully quantum-mechanical and nonperturbative reaction model, is adopted. Results: CdΞ- turns out to be sensitive to the strong interaction and enhanced by the deuteron breakup effect by 6%-8% for a d-Ξ- relative momentum below about 70 MeV/c. Low-lying neutron-neutron continuum states are responsible for this enhancement. Conclusions: Within the adopted model, the deuteron breakup effect on CdΞ- is found to be appreciable but not very significant. Except for the enhancement by several percent, studies on CdΞ- without the deuteron breakup effect can be justified.

DOI： 10.1103/physrevc.103.065205

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Direct proton-knockout reactions of Sc55 at ∼220 MeV/nucleon were studied at the RIKEN Radioactive Isotope Beam Factory. Populated states of Ca54 were investigated through γ-ray and invariant-mass spectroscopy. Level energies were calculated from the nuclear shell model employing a phenomenological internucleon interaction. Theoretical cross sections to states were calculated from distorted-wave impulse approximation estimates multiplied by the shell model spectroscopic factors, which describe the wave function overlap of the Sc55 ground state with states in Ca54. Despite the calculations showing a significant amplitude of excited neutron configurations in the ground-state of Sc55, valence proton removals populated predominantly the ground state of Ca54. This counterintuitive result is attributed to pairing effects leading to a dominance of the ground-state spectroscopic factor. Owing to the ubiquity of the pairing interaction, this argument should be generally applicable to direct knockout reactions from odd-even to even-even nuclei.

DOI： 10.1103/physrevlett.126.252501

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The low-lying level structure of V63 was studied for the first time by the inelastic proton scattering and the proton knock-out reaction in inverse kinematics. The comparison of the newly observed γ-ray transitions at 696(8) keV and 889(16) keV with our shell-model calculations using the Lenzi-Nowacki-Poves-Sieja interaction established two excited states proposed to be the first 11/2- and 9/2- levels. The (p,p′) excitation cross sections were analyzed by the coupled channel formalism assuming pure quadrupole as well as quadrupole+hexadecapole deformations. This resulted in large deformation parameters placing V63 in the island of inversion located below Ni68.

DOI： 10.1103/physrevc.103.064308

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In this review article we discuss the present status of direct nuclear reactions and the nuclear structure aspects one can study with them. We discuss the spectroscopic information we can assess in experiments involving transfer reactions, heavy-ion-induced knockout reactions and quasifree scattering with (p,2p), (p,pn), and (e,e′p) reactions. In particular, we focus on the proton-to-neutron asymmetry of the quenching of the spectroscopic strength.

DOI： 10.1016/j.ppnp.2021.103847

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<title>Abstract</title>
The virtual photon theory (VPT), which is based on first-order Coulomb dissociation restricted to the electric dipole (E1), has been successfully used to explain the breakup data for several cases. Our aim is to study the role of various higher-order processes that are ignored in the VPT, such as the nuclear breakup, interference between nuclear and Coulomb amplitudes, and multistep breakup processes mainly due to strong continuum-continuum couplings in the breakup of two-body projectiles on a heavy target at both intermediate and higher incident energies. For the purpose of numerical calculations, we employed eikonal version of three-body continuum-discretized coupled-channels (CDCC) reaction model. Our results for the breakup of 11Be and 17F on 208Pb target at 100, 250, and 520 MeV/A, show the importance of nuclear breakup contribution, and its significant role in the multistep processes. The multistep effect on Coulomb breakup for core-neutron projectile was found to be negligible, whereas it was important for core-proton projectile. Coulomb-nuclear interference (CNI) effect was also found to be non-negligible. Qantitatively, the multistep effects due to the nuclear breakup was found to depend on the incident energy through the energy dependence of the core-target and nucleon-target nuclear potentials. The nuclear breakup component, the CNI effect, and the multistep breakup processes are all found to be non-negligible; hence, the assumptions adopted in the VPT for the accurate description of breakup cross sections are not valid.

DOI： 10.1093/ptep/ptab055

Language：Others   Publishing type：Research paper (scientific journal)  

<title>Abstract</title>
The triaxial and hexadecapole deformations of the $K^pi=0^+$ and $K^pi=2^+$ bands of $^{24}$Mg have been investigated by the inelastic scatterings of various probes, including electrons, protons, and alpha($alpha$) particles, for a prolonged time. However, it has been challenging to explain the unique properties of the scatterings observed for the $4^+_1$ state through reaction calculations. This paper investigates the structure and transition properties of the $K^pi=0^+$ and $K^pi=2^+$ bands of $^{24}$Mg employing the microscopic structure and reaction calculations via inelastic proton and $alpha$ scattering. In particular, the $E4$ transitions to the $4^+_1$ and $4^+_2$ states are reexamined. The structure of $^{24}$Mg was calculated employing the variation after the parity and total angular momentum projections in the framework of the antisymmetrized molecular dynamics (AMD). The inelastic proton and $alpha$ reactions were calculated by the microscopic coupled-channel (MCC) approach by folding the Melbourne $g$-matrix $NN$ interaction with the AMD densities of $^{24}$Mg. Reasonable results were obtained on the properties of the structure, including the energy spectra and $E2$ and $E4$ transitions of the $K^pi=0^+$ and $K^pi=2^+$ bands owing to the enhanced collectivity of triaxial deformation. The MCC+AMD calculation successfully reproduced the angular distributions of the $4^+_1$ and $4^+_2$ cross sections of proton scattering at incident energies of $E_p=40$–100 MeV and $alpha$ scattering at $E_alpha=100$–400 MeV. This is the first microscopic calculation to describe the unique properties of the $0^+_1 o 4^+_1$ transition. In the inelastic scattering to the $4^+_1$ state, the dominant two-step process of the $0^+_1 o 2^+_1 o 4^+_1$ transitions and the deconstructive interference in the weak one-step process were essential.

DOI： 10.1093/ptep/ptab029

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DOI： 10.1016/j.physletb.2021.136108

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DOI： 10.1103/physrevc.103.l031305

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DOI： 10.1016/j.physletb.2021.136072

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DOI： 10.1103/physrevc.103.l031601

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DOI： 10.1080/00223131.2020.1870010

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A kinematically complete quasifree (p,pn) experiment in inverse kinematics was performed to study the structure of the Borromean nucleus B17, which had long been considered to have a neutron halo. By analyzing the momentum distributions and exclusive cross sections, we obtained the spectroscopic factors for 1s1/2 and 0d5/2 orbitals, and a surprisingly small percentage of 9(2)% was determined for 1s1/2. Our finding of such a small 1s1/2 component and the halo features reported in prior experiments can be explained by the deformed relativistic Hartree-Bogoliubov theory in continuum, revealing a definite but not dominant neutron halo in B17. The present work gives the smallest s- or p-orbital component among known nuclei exhibiting halo features and implies that the dominant occupation of s or p orbitals is not a prerequisite for the occurrence of a neutron halo.

DOI： 10.1103/physrevlett.126.082501

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DOI： 10.1103/physrevc.103.024609

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DOI： 10.1103/physrevc.103.024603

Language：English   Publishing type：Research paper (scientific journal)  

The surface of neutron-rich heavy nuclei, with a neutron skin created by excess neutrons, provides an important terrestrial model system to study dilute neutron-rich matter. By using quasi-free α cluster–knockout reactions, we obtained direct experimental evidence for the formation of α clusters at the surface of neutron-rich tin isotopes. The observed monotonous decrease of the reaction cross sections with increasing mass number, in excellent agreement with the theoretical prediction, implies a tight interplay between α-cluster formation and the neutron skin. This result, in turn, calls for a revision of the correlation between the neutron-skin thickness and the density dependence of the symmetry energy, which is essential for understanding neutron stars. Our result also provides a natural explanation for the origin of α particles in α decay.

DOI： 10.1126/science.abe4688

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Low-lying excited states in the N = 32 isotope Ar-50 were investigated by in-beam gamma-ray spectroscopy following proton- and neutron-knockout, multinucleon removal, and proton inelastic scattering at the RIKEN Radioactive Isotope Beam Factory. The energies of the two previously reported transitions have been confirmed, and five additional states are presented for the first time, including a candidate for a 3(-) state. The level scheme built using gamma gamma coincidences was compared to shell-model calculations in the sd-pf model space and to ab initio predictions based on chiral two- and three-nucleon interactions. Theoretical proton- and neutron-knockout cross sections suggest that two of the new transitions correspond to 2(+) states, while the previously proposed 4(1)(+) state could also correspond to a 2(+) state.

DOI： 10.1103/physrevc.102.064320

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The formation of a dineutron in the Li11 nucleus is found to be localized to the surface region. The experiment measured the intrinsic momentum of the struck neutron in Li11 via the (p,pn) knockout reaction at 246 MeV/nucleon. The correlation angle between the two neutrons is, for the first time, measured as a function of the intrinsic neutron momentum. A comparison with reaction calculations reveals the localization of the dineutron at r∼3.6 fm. The results also support the density dependence of dineutron formation as deduced from Hartree-Fock-Bogoliubov calculations for nuclear matter.

DOI： 10.1103/physrevlett.125.252501

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The discovery of gravitational waves has confirmed old theoretical predictions that binary systems formed with compact stars play a crucial role not only for cosmology and nuclear astrophysics [1]. As a byproduct of these and subsequent observations, it is now clear that neutron-star mergers can be a competitive site for the production of half of the elements heavier than iron in the Universe following a sequence of fast neutron capture reactions known as the r process. In this article we discuss an effect which has been so far neglected in calculations of r-process nucleosynthesis in neutron star mergers. We show that the corrections due to the neutron environment even at relatively small neutron densities, within the bounds of numerical hydrodynamical simulations of neutron star mergers and after the onset of the r process, are non-negligible and need to be taken into account to accurately describe the elemental abundance as determined by observations.

DOI： 10.1088/1361-6471/ab9d06

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Isospin characters of nuclear excitations in Mg-26 and Be-10 are investigated via proton (p) and alpha (alpha) inelastic scattering. A structure model of antisymmetrized molecular dynamics (AMD) is applied to calculate the ground and excited states of Mg-26 and Be-10. The calculation describes the isoscalar feature of the ground-band 2(1)(+) (K-pi = 0(1)(+)) excitation and predicts the neutron dominance of the side-band 2(2)(+) (K-pi = 2(+)) excitation in Mg-26 and Be-10. The p and alpha inelastic scattering off Mg-26 and Be-10 is calculated by microscopic coupled-channel (MCC) calculations with a g-matrix folding approach by using the matter and transition densities of the target nuclei calculated with AMD. The calculation reasonably reproduces the observed 0(1)(+), 2(1)(+), and 2(2)(+) cross sections of Mg-26 + p scattering at incident energies E-p = 24 and 40 MeV and of Mg-26 +alpha scattering at E alpha = 104 and 120 MeV. For Be-10 + p and Be-10 +alpha scattering, inelastic cross sections to the excited states in the K-pi = 0(1)(+) ground, K-pi = 2(+) side, K-pi = 0(2)(+) cluster, and K-pi = 1-cluster bands are investigated. The isospin characters of excitations are investigated via inelastic scattering processes by comparison of the production rates in the Be-10 + p, Be-10 +alpha , and C-10 + p reactions. The result predicts that the 2(2)(+) state is selectively produced by the Be-10 + p reaction because of the neutron dominance in the 2 + 2 excitation as in the case of the Mg-26 + p scattering to the 2(2)(+) state, whereas its production is significantly suppressed in the C-10 + p reaction.

DOI： 10.1103/PhysRevC.102.014607

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The K-pi = 0(1)(+), K-pi = 2(-) , and K-pi = 0(1)(-) bands of Ne-20 are investigated with microscopic structure and reaction calculations via proton and alpha inelastic scattering off Ne-20. Structures of Ne-20 are calculated with variation after parity and total angular momentum projections in the antisymmetrized molecular dynamics (AMD). The K-pi = 0(1)(+) and K-pi = 0(1)(-) bands have O-1(6) + alpha cluster structures, whereas the K-pi = 2(- )band shows a C-12 +2 alpha-like structure. Microscopic coupled-channel calculations of proton and a scattering off Ne-20 are performed by using the proton-nucleus and alpha -nucleus potentials, which are derived by folding the Melbourne g-matrix NN interaction with AMD densities of Ne-20. The calculation reasonably reproduces the observed cross sections of proton scattering at E-p = 25-35 MeV and alpha scattering at E-alpha = 104-386 MeV. Transition properties from the ground to excited states are discussed by reaction analyses of proton and a inelastic processes. Mixing of the K-pi = 2(-) and K-pi = 0(1)(- )bands is discussed by detailed analysis of the 0(1)(+ )-> 3(1)(-) and 0(1)(+ )-> 3(2)(-) transitions. For the 3(1)(-) state, mixing of the K-pi = 0(1)(-) cluster component in the K-pi = 2(-) band plays an important role in the transition properties.

DOI： 10.1103/PhysRevC.101.064308

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0(+), 1(-), 2(+), and 3(-) excitations of Si-28 are investigated via proton and a inelastic scattering off Si-28. The structure calculation of Si-28 is performed with the energy variation after total angular momentum and parity projections in the framework of antisymmetrized molecular dynamics (AMD). As a result of the AMD calculation, the oblate ground and prolate bands, 0(+) and 3(-) excitations, and the 1(-) and 3(-) states of the K-pi = 0(-) band are obtained. Using the matter and transition densities of Si-28 obtained by AMD, microscopic coupled-channels calculations of proton and a scattering off Si-28 are performed. The proton-Si-28 potentials in the reaction calculation are microscopically derived by folding the Melbourne g-matrix NN interaction with the AMD densities of Si-28. The alpha-Si-28 potentials are obtained by folding the nucleon-Si-28 potentials with an alpha density. The calculation reasonably reproduces the observed elastic and inelastic cross sections of proton and alpha scattering. Transition properties are discussed by combining the reaction analysis of proton and a scattering and structure features such as transition strengths and form factors. The isoscalar monopole and dipole transitions are focused.

DOI： 10.1103/PhysRevC.101.064607

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The role of the short-range part (repulsive core) of the proton-neutron (pn) potential in deuteron elastic breakup processes is investigated. A simplified one-range Gaussian potential and the Argonne V4' (AV4') central potential are adopted in the continuum-discretized coupled-channels (CDCC) method. The deuteron breakup cross sections calculated with these two potentials are compared. The repulsive core is found not to affect the deuteron breakup cross sections at energies from 40 MeV to 1 GeV. To understand this result, an analysis of the peripherality of the elastic breakup processes concerning the pn relative coordinate is performed. It is found that for the breakup processes populating the pn continua with orbital angular momentum l different from 0, the reaction process is peripheral, whereas it is not for the breakup to the l = 0 continua (the s-wave breakup). The result of the peripherality analysis indicates that the whole spatial region of deuteron contributes to the s-wave breakup.

DOI： 10.1103/PhysRevC.101.054606

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The structure of a neutron-rich F-25 nucleus is investigated by a quasifree (p, 2p) knockout reaction at 270A MeV in inverse kinematics. The sum of spectroscopic factors of pi 0d(5/2) orbital is found to be 1.0 +/- 0.3. However, the spectroscopic factor with residual O-24 nucleus being in the ground state is found to be only 0.36 +/- 0.13, while those in the excited state is 0.65 +/- 0.25. The result shows that the O-24 core of F-25 nucleus significantly differs from a free O-24 nucleus, and the core consists of similar to 35% O-24(g.s.). and similar to 65% excited O-24. The result may infer that the addition of the 0d(5/2) proton considerably changes neutron structure in F-25 from that in O-24, which could be a possible mechanism responsible for the oxygen dripline anomaly.

DOI： 10.1103/PhysRevLett.124.212502

Language：English   Publishing type：Research paper (scientific journal)  

The heaviest bound isotope of boron B-19 has been investigated using exclusive measurements of its Coulomb dissociation, into B-17 and two neutrons, in collisions with Pb at 220 MeV/nucleon. Enhanced electric dipole (E1) strength is observed just above the two-neutron decay threshold with an integrated E1 strength of B(E1) = 1.64 +/- 0.06(stat) +/- 0.12(sys) e(2) fm(2) for relative energies below 6 MeV. This feature, known as a soft E1 excitation, provides the first firm evidence that B-19 has a prominent two-neutron halo. Three-body calculations that reproduce the energy spectrum indicate that the valence neutrons have a significant s-wave configuration and exhibit a dineutronlike correlation.

DOI： 10.1103/PhysRevLett.124.212503

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We report on the first gamma-ray spectroscopy of K-51,K-53 produced via the Ca-52,Ca-54(p,2p) reactions at similar to 250 MeV/nucleon. Unambiguous final-state angular-momentum assignments were achieved for beam intensities down to few particles per second by using a new technique based on reaction vertex tracking combined with a thick liquid-hydrogen target. Through gamma-ray spectroscopy and exclusive parallel momentum distribution analysis, 3/(2)+ ground states and 1/2(+) first excited states in K-51,K-53 were established quantifying the natural ordering of the 1d(3/2) and 2s(1/2) proton-hole states that are restored at N = 32 and 34. State-of-the-art ab initio calculations and shell-model calculations with improved phenomenological effective interactions reproduce the present data and predict consistently the increase of the E(1/4)- E(3/4) energy differences towards N = 40. (C) 2020 The Authors. Published by Elsevier B.V.

DOI： 10.1016/j.physletb.2020.135215

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The structures of the neutron-rich Co-69,Co-71,Co-73 isotopes were investigated via (p, 2p) knockout reactions at the Radioactive Isotope Beam Factory, RIKEN. Isotopes of interest were studied using the DALI2 gamma-ray detector array combined with the MINOS target and tracker system. Level schemes were reconstructed using the gamma-gamma coincidence technique, with tentative spin-parity assignments based on the measured inclusive and exclusive cross sections. Comparison with shell-model calculations using the Lenzi-Nowacki-Poves-Sieja LNPS and PFSDG-U interactions suggests coexistence of spherical and deformed shapes at low excitation energies in the Co-69,Co-71,Co-73 isotopes. The distorted-wave impulse approximation (DWIA) framework was used to calculate the single-particle cross sections. These values were compared with the experimental findings.

DOI： 10.1103/PhysRevC.101.034314

Language：English   Publishing type：Research paper (scientific journal)  

Cluster structures of C-14 were investigated with a method of antisymmetrized molecular dynamics (AMD) combined with a 3 alpha + nn cluster model while focusing on the monopole excitations and the linear-chain 3a band. Variation after parity and angular-momentum projections was performed in the AMD framework, and the generator coordinate method was applied to take into account various 3 alpha + nn cluster configurations. Energy spectra and monopole and E2 transition strengths of 0(+), 2(+), and 4(+) states were calculated to assign band structures. The 0(3)(+) state with remarkable monopole transitions was obtained as a vibrational mode of the triangle 3 alpha configuration. In addition, the linear-chain 3 alpha band from the bandhead 0(4)(+) state was obtained. Be-10 +alpha decay widths of 0(+), 2(+), and 4(+) states were evaluated. alpha inelastic scattering off C-14 was also investigated by the microscopic coupled-channel calculation with the g-matrix folding model to propose possible observation of the 0(3)(+) state via alpha scattering experiments.

DOI： 10.1103/PhysRevC.101.014317

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Shell evolution of N=40 isotones towards 60Ca: First spectroscopy of 62Ti
Excited states in the N=40 isotone Ti were populated via the V(p,2p) Ti reaction at ∼200 MeV/nucleon at the Radioactive Isotope Beam Factory and studied using γ-ray spectroscopy. The energies of the 2 →0 and 4 →2 transitions, observed here for the first time, indicate a deformed Ti ground state. These energies are increased compared to the neighboring Cr and Fe isotones, suggesting a small decrease of quadrupole collectivity. The present measurement is well reproduced by large-scale shell-model calculations based on effective interactions, while ab initio and beyond mean-field calculations do not yet reproduce our findings. The shell-model calculations for Ti show a dominant configuration with four neutrons excited across the N=40 gap. Likewise, they indicate that the N=40 island of inversion extends down to Z=20, disfavoring a possible doubly magic character of the elusive Ca. 62 63 62 + + + + 62 64 66 62 60 1 gs 1 1

DOI： 10.1016/j.physletb.2019.135071

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A dipole resonance of 11Li is found by a 9Li + n + n three-body model analysis with the complexscaling method. The resonance can be interpreted as a bound state in the 10Li + n system, i.e., a Feshbach resonance in the 9Li + n + n system. As a characteristic feature of the Feshbach resonance of 11Li, the 10Li + n threshold is open above the 9Li + n + n one, which reflects a distinctive property of the Borromean system. A microscopic four-body reaction calculation for the 11Li(p,p) reaction at 6 MeV/nucleon is performed by taking into account the resonant and nonresonant continuum states of the three-body system. The calculation of angular distributions of the elastic and inelastic scattering as well as the energy spectrum reproduced a recent experimental result. Furthermore, the E1 strength distribution from a Coulomb dissociation experiment was also reproduced in this framework. This means that the existence of the Borromean Feshbach resonance may consistently answer a long-standing open question of an excited state of 11Li.

DOI： 10.1093/ptep/ptz126

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Background: Proton-induced nucleon knockout (p, pN) reactions have been successfully used to study the single-particle nature of stable nuclei in normal kinematics with the distorted-wave impulse approximation (DWIA) framework. Recently, these reactions have been applied to rare-isotope beams at intermediate energies in inverse kinematics to study the quenching of spectroscopic factors.Purpose: Our goal is to investigate the effects of various corrections and uncertainties within the standard DWIA formalism on the (p, pN) cross sections. The consistency of the extracted reduction factors between DWIA and other methods is also evaluated.Method: We analyze the (p, 2p) and (p, pn) reaction data measured at the (RB)-B-3-LAND setup at GSI for carbon, nitrogen, and oxygen isotopes in the incident energy range of 300-450 MeV/u. Cross sections and reduction factors are calculated by using the DWIA method. The transverse momentum distribution of the C-12(p, 2p)B-11 reaction is also investigated.Results: We have found that including the nonlocality corrections and the Moller factor affects the cross sections considerably. The proton-neutron asymmetry dependence of reduction factors extracted by the DWIA calculation is very weak and consistent with those given by other reaction methods and ab initio structure calculations.Conclusions: The results found in this work provide a detailed investigation of the DWIA method for (p, pN) reactions at intermediate energies. They also suggest that some higher-order effects, which is essential for an accurate cross-section description at large recoil momentum, is missing in the current DWIA and other reaction models.

DOI： 10.1103/PhysRevC.100.064604

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Lithium-11 is a showcase of neutron halos and has been providing new insight to nuclear structure researches. Recently, an isoscalar resonance at low excitation energy (Ex 1MeV) has been confirmed by the development of a low-energy high-intensity beam of 11Li at TRIUMF. By inelastic scattering measurements (p, p) and (d, d) with inverse kinematics, the first excited state of 11Li has been studied in detail and an isoscalar nature of the transitions has been confirmed and a strong transition amplitude has been observed indicating the soft-resonance of 11Li. Those recent experimental results on the excitation of the soft resonance are described and then recent theoretical developments based on the four-body continuum-discretized coupled-channels 11Li + p system are presented together with a brief history of the resonance search in Li-11.

DOI： 10.1140/epja/i2019-12852-9

Language：English   Publishing type：Research paper (scientific journal)  

Microscopic coupled-channel calculations of inelastic proton scattering are performed to study neutron excitations in the 2(1)(+) states of O-18, Be-10, Be-12,and C-16. The proton-nucleus potentials in the coupled-channel calculation are microscopically derived by folding the Melbourne g-matrix NN interaction with the matter and transition densities of the target nuclei obtained via structure model calculations of the antisymmetrized molecular dynamics. The calculated results reasonably reproduce the elastic and inelastic proton scattering cross section, and support the dominant contribution of neutrons in the 2(1)(+) excitation of Be-12 and C-16 as well as O-18. The sensitivity of the inelastic scattering cross sections to the neutron transition density is discussed as well as the exotic behavior of the neutron transition density with amplitude in the outer regions of Be-12 and C-16.

DOI： 10.1103/PhysRevC.100.064616

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To discuss a possible observation of large-amplitude nuclear shape mixing by nuclear reaction, we employ a simple collective model and evaluate the transition densities with which the differential cross sections are obtained through the microscopic coupled-channel calculation. Assuming the spherical-to-prolate shape transition, we focus on large-amplitude shape mixing associated with the softness of the collective potential in the beta direction. We introduce a simple model based on the five-dimensional quadrupole collective Hamiltonian, which simulates a chain of isotopes that exhibit spherical-to-prolate shape phase transition. Taking Sm-154 as an example and controlling the model parameters, we study how the large-amplitude shape mixing affects the elastic and inelastic proton scatterings. The calculated results suggest that the inelastic cross section of the 2(2)(+) state shows us the important role of the quadrupole shape mixing.

DOI： 10.1093/ptep/ptz095

Language：English   Publishing type：Research paper (scientific journal)  

Background: The proton-induced alpha knockout reaction has been utilized for decades to investigate the alpha cluster formation in the ground state of nucleus. However, even today, the theoretical description of the reaction is not precise enough for the quantitative study. For example, the alpha spectroscopic factors reduced from alpha knockout experiments with reaction analyses using phenomenological alpha cluster wave functions disagree with those given by a structure theory. In some cases they also scatter depending on the kinematical condition of the experiment. This suggests that the theoretical description of the alpha knockout reaction is insufficient from a quantitative viewpoint.Purpose: We show that the distorted wave impulse approximation can describe Ne-20(p, p alpha)O-16 reaction quantitatively if reliable inputs are used; the optical potential, the p-alpha cross section, and the alpha cluster wave function. We also investigate the relationship between the alpha cluster wave function and the alpha knockout cross section.Method: The Ne-20(p, p alpha)O-16 reaction is described by the distorted wave impulse approximation. An input of the calculation, the alpha-O-16 cluster wave function, is obtained by the antisymmetrized molecular dynamics and the Laplace expansion method.Results: In contrast to the previous work, the Ne-20(p, p alpha)O-16 data at 101.5 MeV is successfully reproduced by the present framework without any free adjustable parameters. It is also found that the knockout cross section is sensitive to the surface region of the cluster wave function because of the peripherality of the reaction.Conclusions: Using a reliable alpha cluster wave function, p-alpha cross section, and distorting potentials, it is found that the Ne-20(p, p alpha)O-16 cross section is quantitatively reproduced by the present framework. This success demonstrates that the proton-induced alpha knockout reaction is a quantitative probe for the alpha clustering.

DOI： 10.1103/PhysRevC.100.044601

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Quasifree Neutron Knockout from 54Ca Corroborates Arising N=34 Neutron Magic Number
Exclusive cross sections and momentum distributions have been measured for quasifree one-neutron knockout reactions from a Ca-54 beam striking on a liquid hydrogen target at similar to 200 MeV/u. A significantly larger cross section to the p(3/2), state compared to the f(5/2) state observed in the excitation of Ca-53 provides direct evidence for the nature of the N = 34 shell closure. This finding corroborates the arising of a new shell closure in neutron-rich calcium isotopes. The distorted-wave impulse approximation reaction formalism with shell model calculations using the effective GXPF1Bs interaction and ab initio calculations concur our experimental findings. Obtained transverse and parallel momentum distributions demonstrate the sensitivity of quasifree one-neutron knockout in inverse kinematics on a thick liquid hydrogen target with the reaction vertex reconstructed to final state spin-parity assignments.

DOI： 10.1103/PhysRevLett.123.142501

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.nuclphysa.2019.02.005

Language：English   Publishing type：Research paper (scientific journal)  

Background: Recent theoretical and experimental researches using proton-induced alpha-knockout reactions provide direct manifestation of alpha-cluster formation in nuclei. In recent and future experiments, alpha-knockout data are available for neutron-rich beryllium isotopes. In Be-12, rich phenomena are induced by the formation of a clusters surrounded by neutrons; for instance, breaking of the neutron magic number N = 8.Purpose: Our objective is to provide direct probing of the alpha-cluster formation in the Be-12 target through associating the structure information obtained by a microscopic theory with the experimental observables of alpha-knockout reactions.Method: We formulate a new wave function of the Tohsaki-Horiuchi-Schuck-Ropke (THSR) type for the structure calculation of Be-12 nucleus and integrate it with the distorted-wave impulse-approximation framework for the alpha-knockout reaction calculation of Be-12(p, p alpha)He-8.Results: We reproduce the low-lying spectrum of the Be-12 nucleus by using the THSR wave function and discuss the cluster structure of the ground state. Based on the microscopic wave function, the optical potentials and alpha-cluster wave function are determined and utilized in the calculation of Be-12(p, p alpha)He-8 reaction at 250 MeV. The possibility of probing the clustering state of Be-12 through this reaction is demonstrated by analysis of the triple differential cross sections that depend sensitively on the alpha-cluster amplitude at the nuclear surface.Conclusions: This study provides a feasible approach to validate directly the theoretical predictions of clustering features in the Be-12 nucleus through the alpha-knockout reaction.

DOI： 10.1103/PhysRevC.99.064610

Language：English   Publishing type：Research paper (scientific journal)  

alpha elastic and inelastic scattering on C-12 is investigated with the coupled-channels calculation by using microscopic alpha-C-12 potentials, which are derived by folding the Melbourne g-matrix NN interaction with the densities of alpha and C-12. The matter and transition densities of C-12 are obtained by a microscopic structure model of the antisymmetrized molecular dynamics combined with and without the 3 alpha generator coordinate method. The calculation reproduces satisfactorily well the observed elastic and inelastic cross sections at incident energies of E-alpha = 130, 172.5, 240, and 386 MeV without phenomenological fitting parameters adjusted to hadron scattering reactions. Isoscalar monopole and dipole excitations to the 0(2)(+), 0(3)(+), and 1(1)(-) states in the alpha scattering are discussed.

DOI： 10.1103/PhysRevC.99.064601

Language：English   Publishing type：Research paper (scientific journal)  

First microscopic coupled-channels calculation of cross sections for inelastic alpha scattering off O-16
The alpha inelastic scattering on O-16 is investigated with the coupled-channels calculation using the alpha-nucleus coupled-channels potentials, which are microscopically derived by folding the the Melbourne g-matrix NN interaction with the O-16 and alpha densities. The matter and transition densities of O-16 are calculated by a microscopic structure model of the variation after the spin-parity projections combined with the generator coordinate method of C-12 + alpha in the framework of the antisymmetrized molecular dynamics. The calculation reproduces the observed elastic and inelastic cross sections at incident energies of E-alpha = 104, 130, 146, and 386 MeV. The coupled-channels effect on the cross sections is also discussed.

DOI： 10.1103/PhysRevC.99.064608

Language：English   Publishing type：Research paper (scientific journal)  

78Ni revealed as a doubly magic stronghold against nuclear deformation
Nuclear magic numbers correspond to fully occupied energy shells of protons or neutrons inside atomic nuclei. Doubly magic nuclei, with magic numbers for both protons and neutrons, are spherical and extremely rare across the nuclear landscape. Although the sequence of magic numbers is well established for stable nuclei, experimental evidence has revealed modifications for nuclei with a large asymmetry between proton and neutron numbers. Here we provide a spectroscopic study of the doubly magic nucleus 78 Ni, which contains fourteen neutrons more than the heaviest stable nickel isotope. We provide direct evidence of its doubly magic nature, which is also predicted by ab initio calculations based on chiral effective-field theory interactions and the quasi-particle random-phase approximation. Our results also indicate the breakdown of the neutron magic number 50 and proton magic number 28 beyond this stronghold, caused by a competing deformed structure. State-of-the-art phenomenological shell-model calculations reproduce this shape coexistence, predicting a rapid transition from spherical to deformed ground states, with 78 Ni as the turning point.

DOI： 10.1038/s41586-019-1155-x

Language：English   Publishing type：Research paper (scientific journal)  

The understanding of nucleon (N) and triton emissions from nucleon-Li-7 collision is important for the development of some fusion-related facilities. Both nucleon and triton emissions from nucleon-induced reactions on Li-7 leading to three final particles at incident energies below 20 MeV are analyzed by using a three-body continuum discretized coupled-channels method (CDCC), final-state interaction (FSI) model, and sequential decay (SD) model. The CDCC is applied to predict nucleon and triton emissions via breakup continuum channels, Li-7(N, N')Li-7* -> t + alpha. Triton emission from the p(n) + Li-7 -> t Li-5(He-5) channel and nucleon emission from sequential decay of the ground-state Li-5(He-5) are described by the FSI model and the SD model, respectively. The double differential cross sections (DDXs) of nucleon and triton emissions are calculated and compared with experimental data. In most cases, the calculated DDXs are in good agreement with the measured ones except at relatively low nucleon emission energies. It is clarified that triton production takes place mainly via the breakup continuum channels.

DOI： 10.1103/PhysRevC.99.034602

Language：English   Publishing type：Research paper (scientific journal)  

Recently, we have determined surface distributions of a clusters in the ground state of Ne-20 from alpha-transfer cross sections, without investigating the properties of its excited states. In this paper we extend our comprehension of alpha-cluster structures in excited states of nuclei through reaction studies. In particular we focus on O-16, for which attention has been paid to advances of structure theory and assignment regarding 4(+)-resonance states. We study the surface manifestation of the alpha-cluster states in both the ground and excited states of O-16 from the analysis of the a-transfer reaction C-12(Li-6, d)O-16. The alpha-transfer reaction is described by the distorted-wave Born approximation. We test two microscopic wave functions as an input of reaction calculations. Then a phenomenological potential model is introduced to clarify the correspondence between cluster-wave functions and transfer-cross sections. Surface peaks of the alpha-wave function of O-16(0(+)) are sensitively probed by transfer-cross sections at forward angles, while it remains unclear how we trace the surface behavior of O-16(4(+)) from the cross sections. From inspection of the cross sections at forward angles, we are able to specify that the alpha-cluster structure in the 0(1)(+)- and 0(2)(+) states prominently manifests itself at the radii similar to 4 and similar to 4.5 fm, respectively. It is remarkable that the 4(1)(+) state has the C-12 + alpha-cluster component with the surface peak at the radius similar to 4 or outer, whereas the C-12 + alpha-cluster component in the 4(2)(+) state is found not to be dominant. The 4(2)(+) state is difficult to be interpreted by a simple potential model assuming the C-12 + alpha configuration only. (C) 2019 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nuclphysa.2018.12.024

Language：Others   Publishing type：Research paper (scientific journal)  

Recently, we have determined surface distributions of α clusters in the ground state of Ne20 from α-transfer cross sections, without investigating the properties of its excited states. In this paper we extend our comprehension of α-cluster structures in excited states of nuclei through reaction studies. In particular we focus on O16, for which attention has been paid to advances of structure theory and assignment regarding 4+-resonance states. We study the surface manifestation of the α-cluster states in both the ground and excited states of O16 from the analysis of the α-transfer reaction C12(Li6,d)16O. The α-transfer reaction is described by the distorted-wave Born approximation. We test two microscopic wave functions as an input of reaction calculations. Then a phenomenological potential model is introduced to clarify the correspondence between cluster-wave functions and transfer-cross sections. Surface peaks of the α-wave function of O16(0+) are sensitively probed by transfer-cross sections at forward angles, while it remains unclear how we trace the surface behavior of O16(4+) from the cross sections. From inspection of the cross sections at forward angles, we are able to specify that the α-cluster structure in the 01+ and 02+ states prominently manifests itself at the radii ∼4 and ∼4.5 fm, respectively. It is remarkable that the 41+ state has the C12+α-cluster component with the surface peak at the radius ∼4 or outer, whereas the C12+α-cluster component in the 42+ state is found not to be dominant. The 42+ state is difficult to be interpreted by a simple potential model assuming the C12+α configuration only.

DOI： 10.1016/j.nuclphysa.2018.12.024

Language：English   Publishing type：Research paper (scientific journal)  

In-beam γ-ray spectroscopy of 136Te at relativistic energies

Language：English   Publishing type：Research paper (scientific journal)  

Coulomb breakup reactions of Zr have been studied in inverse kinematics at incident beam energies of about 200 MeV/nucleon in order to evaluate neutron capture reaction methods. The Zr(n,)Zr reaction is particularly important as a candidate nuclear transmutation reaction for the long-lived fission product Zr in nuclear power plants. One- and two-neutron removal cross sections on Pb and C targets were measured to deduce the inclusive Coulomb breakup cross sections, 375 29 (stat.) 30 (syst.) and 403 26 (stat.) 31 (syst.) mb for Zr and Zr, respectively. The results are compared with estimates using the standard Lorentzian model and microscopic calculations. The results reveal a possible contribution of the pygmy dipole resonance or giant quadrupole resonance in the Coulomb breakup reactions of Zr.

DOI： 10.1093/ptep/pty138

Language：English   Publishing type：Research paper (scientific journal)  

Nuclear structure of 76Ni by (p,2p) reaction

Language：English   Publishing type：Research paper (scientific journal)  

The electromagnetic transitions of Be-9 with linearly polarized gamma rays are calculated by using the alpha + alpha + n three-body model and the complex-scaled solutions of the Lippmann-Schwinger equation; the azimuthal angle distributions of the emitted neutrons are investigated. We calculate the anisotropy parameter as a function of the photon incident energy E-gamma and discuss how sensitive the anisotropy parameter is to nuclear structure and transition modes. The result suggests that the azimuthal angle distribution of neutrons emitted from the Be-9(gamma, n) reaction with the linearly polarized gamma rays is useful to identify the resonances in the final states even if it is not clearly observed in the cross section.

DOI： 10.1103/PhysRevC.98.064611

Language：English   Publishing type：Research paper (scientific journal)  

Background: Nuclear clustering has been one of the main interests in nuclear physics. In order to probe the alpha clustering through reaction observables, alpha transfer and alpha knockout reactions have been studied. It is very important to probe the alpha cluster amplitude at nuclear surface since the alpha spectroscopic factor is not necessarily alpha direct measure of the alpha clustering.Purpose: Our goal is to reveal how the alpha cluster amplitude is probed through alpha knockout reactions depending on reaction conditions, e.g., the incident energy.Method: We consider Ne-20(p, p alpha)O-1(6) and Sn-120(p, p alpha)Cd-116 at 100-400 MeV within the distorted wave impulse approximation (DWIA) framework. We introduce a masking function, which shows how the reaction amplitude in the nuclear interior is suppressed and defines the probed region of the alpha cluster wave function.Results: It is clearly shown by means of the masking function that the alpha knockout reaction probes the alpha cluster amplitude in the nuclear surface region, which is the direct measure of well-developed alpha cluster states. The incident energy dependence of the masking effect is investigated, using alpha simplified form of the masking function.Conclusions: The alpha knockout reaction can probe the alpha cluster amplitude in the nuclear surface region by choosing proper kinematics owing to the masking effect originated from absorptions of distorting potentials, and is a suitable method to investigate how alpha cluster states are spatially developed.

DOI： 10.1103/PhysRevC.98.024614

Language：English   Publishing type：Research paper (scientific journal)  

Background: Proton-induced alpha-knockout reactions may allow direct experimental observation of alpha clustering in nuclei. This is obtained by relating the theoretical descriptions of clustering states to the experimental reaction observables. It is desired to introduce microscopic structure models into the theoretical frameworks for alpha-knockout reactions.Purpose: Our goal is to probe the alpha clustering in the Be-10 nucleus by proton-induced alpha-knockout reaction observables.Method: We adopt an extended version of the Tohsaki-Horiuchi-Schuck-Ropke wave function of Be-10 and integrate it with the distorted-wave impulse approximation framework for the calculation of (p, p alpha)-knockout reactions.Results: We make the first calculation for the Be-10(p, p alpha) He-6 reaction at 250 MeV by implementing a microscopic alpha-cluster wave function, and we predict the triple-differential cross section (TDX). Furthermore, by constructing artificial states of the target nucleus Be-10 with compact or dilute spatial distributions, the TDX is found to be highly sensitive to the extent of clustering in the target nuclei.Conclusions: These results provide reliable manifestation of alpha clustering in Be-10.

DOI： 10.1103/PhysRevC.97.044612

Language：English   Publishing type：Research paper (scientific journal)  

Background: Proton-induced knockout reactions of the form (p,pN) have experienced a renewed interest in recent years due to the possibility of performing these measurements with rare isotopes, using inverse kinematics. Several theoretical models are being used for the interpretation of these new data, such as the distorted-wave impulse approximation (DWIA), the transition amplitude formulation of the Faddeev equations due to Alt, Grassberger, and Sandhas (FAGS) and, more recently, a coupled-channels method here referred to as transfer-to-the- continuum (TC). Purpose: Our goal is to compare the momentum distributions calculated with the DWIA and TC models for the same reactions, using whenever possible the same inputs (e.g., distorting potential). A comparison with already published results for the FAGS formalism is performed as well. Method: We choose the C15(p,pn)C14 reaction at an incident energy of 420 MeV/u, which has been previously studied with the FAGS formalism. The knocked-out neutron is assumed to be in a 2s single-particle orbital. Longitudinal and transverse momentum distributions are calculated for different assumed separation energies. Results: For all cases considered, we find a very good agreement between DWIA and TC results. The energy dependence of the distorting optical potentials is found to affect in a modest way the shape and magnitude of the momentum distributions. Moreover, when relativistic kinematics corrections are omitted, our calculations reproduce remarkably well the FAGS result. Conclusions: The results found in this work provide confidence on the consistency and accuracy of the DWIA and TC models for analyzing momentum distributions for (p,pn) reactions at intermediate energies.

DOI： 10.1103/PhysRevC.97.024608

Language：English   Publishing type：Research paper (scientific journal)  

The dependence of the single-particle strength on the difference between proton and neutron separation energies is studied for oxygen isotopes in a wide range of isospins. The cross sections of the quasi-free (p, 2p) reaction on O-14,O-16,O-18,O-22,O-24 were measured at intermediate energies. The measured cross sections are compared to predictions based on the distorted wave impulse approximation and shell-model psd valence-space spectroscopic factors. The reduction factors, which are the ratio of the experimental cross sections to the theoretical predictions, show no apparent dependence on the proton-neutron separation energy difference. The result is compatible with the result of the (e, e'p) reaction on stable targets and with the predictions of recent ab initio calculations.

DOI： 10.1093/ptep/pty011

Language：English  

Theoretical model analysis of $(d,xn)$ reactions on $^7$Li at 25, 40, and 102 MeV
In recent years, the demand for intense neutron sources has been increasing in various applications such as nuclear transmutation of high-level radioactive waste and medical radioisotopes production. Deuteron accelerator-based neutron sources are promised as one of the candidates. Therefore, we have developed a code system dedicated for the deuteron-induced reactions, called DEURACS. In the present work, we focus on deuteron-induced neutron production from $^7$Li target. The calculated double differential cross sections for $(d,xn)$ reactions at incident energies of 25, 40, and 102 MeV are compared with the measured ones, and the applicability of DEURACS is discussed.

DOI： 10.11484/jaea-conf-2017-001

Language：Japanese  

Language：Others   Publishing type：Research paper (scientific journal)  

Reexamination of microscopic optical potentials based on multiple scattering theory
Microscopic optical potentials have been successful in describing<br />
nucleon-nucleus and nucleus-nucleus scattering. Some essential ingredients of<br />
the framework, however, have not been examined in detail. Applicability of the<br />
microscopic folding model is systematically investigated. Effect of an<br />
antisymmetrization factor (ASF) appearing in multiple scattering theory,<br />
theoretical uncertainty regarding the local density approximation (LDA), and<br />
the validity of a prescription for nonlocality, the Brieva-Rook (BR)<br />
localization, of the microscopic potential, are quantitatively estimated for<br />
nucleon-nucleus scattering; investigation on the ASF is carried out for also<br />
deuteron-nucleus scattering. A single folding model with the Melbourne g-matrix<br />
interaction and the SLy4 Skyrme-type Hartree-Fock-Bogoliubiv (SLy4-HFB) density<br />
is employed for evaluating a nucleon-nucleus microscopic optical potential.<br />
Deuteron-nucleus scattering is described by the continuum-discretized<br />
coupled-channels method incorporating the microscopic proton-nucleus and<br />
neutron-nucleus potentials. The ASF is found to affect proton total reaction<br />
cross sections for a 12C target below 200 MeV by about 10%. Effect of the ASF<br />
on total reaction cross sections is negligibly small if a target nucleus is<br />
heavy or scattering energy is above 200 MeV; elastic cross sections are hardly<br />
affected by the ASF for all the reaction systems considered. Below 65 MeV,<br />
still the BR localization works quite well. However, at energies below about 50<br />
MeV, the LDA becomes less accurate for evaluating elastic cross sections at<br />
backward angles. This is the case also for the total reaction cross sections of<br />
p-12C below about 200 MeV. The microscopic model is applicable to<br />
nucleon-nucleus scattering above 25 MeV for target nuclei in a wide range of<br />
mass numbers. Deviation of calculated results from experimental data is less<br />
than about 10%.

Language：English  

DOI： 10.1103/PhysRevC.96.059905

Language：English   Publishing type：Research paper (scientific journal)  

In-beam gamma-ray spectroscopy of Cu-79 is performed at the Radioactive Isotope Beam Factory of RIKEN. The nucleus of interest is produced through proton knockout from a Zn-80 beam at 270 MeV/nucleon. The level scheme up to 4.6 MeV is established for the first time and the results are compared to Monte Carlo shell-model calculations. We do not observe significant knockout feeding to the excited states below 2.2 MeV, which indicates that the Z = 28 gap at N = 50 remains large. The results showthat the Cu-79 nucleus can be described in terms of a valence proton outside a Ni-78 core, implying the magic character of the latter.

DOI： 10.1103/PhysRevLett.119.192501

Language：English  

DOI： 10.1103/PhysRevC.96.059906

Language：English   Publishing type：Research paper (scientific journal)  

We propose to use proton knockout reactions (p, 2p) from a deeply bound orbit as a new probe into three-nucleon-force (3NF) effects. The remarkable advantage of using (p, 2p) reaction is that we can choose an appropriate kinematical condition to probe the 3NF effects. We analyze (p, 2p) reactions on a Ca-40 target within the framework of distorted-wave impulse approximation with a g-matrix interaction based on chiral two-and three-nucleon forces. The chiral 3NF effects significantly change the peak height of the triple differential cross section of (p, 2p) reaction. We also clarify the correspondence between the (p, 2p) cross sections and the in-medium pp cross sections.

DOI： 10.1103/PhysRevC.96.024609

Language：Others  

Four- and three-body breakup mechanism of 6Li elastic scattering

Language：English   Publishing type：Research paper (other academic)  

Although several analyses of the α-transfer reaction16O(6Li, d)20Ne using the distorted wave Born approximation have been performed with the aim to clarify the α-cluster structure of20Ne, they have resulted in poor information on the clustering due to insufficiency of models for the analyses. In this work we propose a precise model employing the coupled-channels Born approximation with the microscopically calculated cluster wave function to elucidate the surface manifestation of the α-particle in the ground state of20Ne. Our calculation has shown improvement of the theoretical calculation compared with that in the previous analyses. We have confirmed numerically that the angular distributed cross section at the forward angles probes only the surface region of the α-cluster wave function. The breakup effect of6Li has been investigated and concluded that only the back coupling is important for the (6Li, d) reaction.

DOI： 10.1088/1742-6596/863/1/012036

Language：English   Publishing type：Research paper (scientific journal)  

Background: Deuteron-induced one-neutron transfer reactions have been used to extract single-particle properties of nuclei, and the adiabatic (AD) approximation is often used to simply treat the deuteron breakup states. Purpose: The primary goal is to examine the validity of the AD approximation for the (d,p) reaction systematically. We clarify also the role of the closed channels often ignored in the description of breakup reactions.Methods: We calculate the (d,p) cross sections with the continuum-discretized coupled-channels method (CDCC) for 128 reaction systems and compare the results with those obtained by the CDCC calculation with the AD approximation. Effect of the closed channels are investigated by ignoring them in CDCC.Results: The AD approximation affects in general the (d,p) cross section by less than 20%, but some exceptional (nonadiabatic) cases for which the AD approximation breaks down are found. The closed channels turn out to have significant effects on the cross section at deuteron energies less than about 10 MeV.Conclusions: The use of the AD approximation in the description of the (d,p) reaction can be justified in many cases, with the uncertainty of less than about 20%. The existence of some nonadiabatic cases nevertheless should be realized. The neglect of the closed channels without confirming the convergence of the CDCC result is not recommended.

DOI： 10.1103/PhysRevC.95.064608

Language：English  

Proton-induced knockout reactions with polarized and unpolarized beams

Language：English  

Analysis of $(d,xn)$ reactions on $^{9}$Be and $^{12}$C
We are conducting a theoretical research on deuteron-induced reaction together with Kyushu University and Research Center for Nuclear Physics (RCNP) of Osaka University. The research outcomes achieved in fiscal year 2016 are summarized as a part of the annual report of RCNP. In recent years, accelerator neutron sources using $(d,xn)$ reactions on light nuclei (Li, Be, C, etc.) are proposed for applications in various fields. Engineering design of such facilities requires accurate prediction of $(d,xn)$ reactions on light nuclei in a wide incident energy range. Therefore, we have developed a physics-based computational code system dedicated for deuteron-induced reactions, called DEURACS. In fiscal year 2016, we calculated double-differential neutron yields from deuteron bombardment on thick $^{9}$Be and $^{12}$C targets, and the calculation reproduced the experimental data quantitatively well in the incident energy range up to 50 MeV. From the results, it has been found that DEURACS can accurately predict $(d,xn)$ reactions on light nuclei in a wide incident energy range. In addition, component-by-component analysis has revealed that the nonelastic breakup reactions make the most dominant contribution to neutron production.

Language：English   Publishing type：Research paper (scientific journal)  

We reexamine the deuteron elastic breakup cross sections on C-12 and Be-10 at low incident energies, for which a serious discrepancy between the continuum-discretized coupled-channels (CDCC) method and the Faddeev-Alt-Grassberger-Sandhas (FAGS) theory was pointed out. We show the closed channels neglected in the preceding study affect significantly the breakup cross section calculated with the CDCC method, resulting in good agreement with the result of FAGS theory.

DOI： 10.1103/PhysRevC.94.051603

Language：English   Publishing type：Research paper (scientific journal)  

To discuss the dineutron correlation in the ground state, the quasi-free neutron knockout reaction on He-6 is investigated. In the present work, the momentum distribution of the two emitted neutrons is calculated with the alpha + n + n three-body model and a simple reaction model to assess the effects of the knockout process via the He-5 resonance and the target dependence in the momentum distribution. A clear signature of the dineutron correlation can be obtained by choosing the kinematical condition so the process via the He-5 resonance is excluded because the He-5 resonance drastically changes the momentum distribution. Using the proton target is important in the quantitative discussion on the dineutron correlation by the knockout reaction. In addition to theoretical arguments, a possible experimental setup to determine the dineutron correlation via the quasi-free knockout reaction is considered.

DOI： 10.1093/ptep/ptw148

Language：English   Publishing type：Research paper (scientific journal)  

The microscopic effective reaction theory is applied to deuteron-induced reactions. A reaction model space characterized by a p + n + A three-body model is adopted, where A is the target nucleus, and the nucleon-target potential is described by amicroscopic folding model based on an effective nucleon-nucleon interaction in nuclear medium and a one-body nuclear density of A. The three-body scattering wave function in the model space is obtained with the continuum-discretized coupled-channels (CDCC) method, and the eikonal reaction theory (ERT), an extension of CDCC, is applied to the calculation of neutron removal cross sections. Elastic scattering cross sections of deuteron on Ni-58 and Pb-208 target nuclei at several energies are compared with experimental data. The total reaction cross sections and the neutron removal cross sections at 56 MeV on 14 target nuclei are calculated and compared with experimental values.

DOI： 10.1103/PhysRevC.94.044619

Language：English   Publishing type：Research paper (scientific journal)  

The Sn-120(p, p alpha) Cd-116 reaction at 392 MeV is investigated with the distorted wave impulse approximation (DWIA) framework. We show that this reaction is very peripheral, mainly because of the strong absorption of alpha by the reaction residue Cd-116, and the alpha clustering on the nuclear surface can be probed clearly. We investigate also the validity of the so-called factorization approximation that has frequently been used so far. It is shown that the kinematics of alpha in the nuclear interior region is significantly affected by the distortion of Cd-116, but it has no effect on the reaction observables because of the strong absorption in that region.

DOI： 10.1103/PhysRevC.94.044604

Language：English   Publishing type：Research paper (scientific journal)  

The single-neutron and -proton removal reactions of Ne-30 with large separation-energy asymmetry vertical bar Delta S vertical bar = vertical bar S-n - S-p vertical bar at incident energies of about 230 MeV/nucleon are measured. In the case of the deeply bound nucleon removal data, a large disagreement is obtained from the theoretical cross sections calculated using the eikonal reaction theory, with nuclear structure inputs from the many-body shell-model theory and the antisymmetrized molecular dynamics theory, respectively. Such a discrepancy is consistent with the systematics observed from the knockout reactions at incident energies similar to 100 MeV/nucleon.

DOI： 10.1093/ptep/ptw096

Language：English   Publishing type：Research paper (scientific journal)  

Background: In the design of deuteron accelerator neutron sources, accurate nuclear data of deuteron-induced reactions are indispensable over a wide range of incident energy. Reliable model calculations play an important role in completing the necessary nuclear data since currently available experimental data are insufficient. We have been developing a code system dedicated for the deuteron-induced reactions, called deuteron-induced reaction analysis code system (DEURACS). It was applied successfully to (d,xp) reactions at 56 and 100 MeV.Purpose: The purpose of the present work is to investigate the applicability of DEURACS to (d,xn) reactions on Be-9 and C-12 for incident energies below 50 MeV and to clarify neutron production mechanism.Methods: Double-differential thick target neutron yields (TTNYs) from deuteron bombardment on thick Be and C targets are analyzed. The TTNYs are derived using the double differential (d,xn) cross sections calculated by DEURACS and the stopping power of deuteron in the target. The calculated TTNYs are decomposed into individual components corresponding to elastic breakup, proton stripping, and statistical decay reactions.Results: The calculated TTNYs reproduced the experimental data quantitatively well in the incident energy range up to 50 MeV. From the analysis, it was found that the proton stripping reaction makes the most dominant contribution to neutron production.Conclusions: DEURACS is applicable to (d,xn) reactions on Be-9 and C-12 for incident energies below 50 MeV. Modeling of the stripping reaction is essential to predict neutron production yields accurately in the design of deuteron accelerator neutron sources.

DOI： 10.1103/PhysRevC.94.014618

Language：English   Publishing type：Research paper (scientific journal)  

We analyze the alpha-C-12 inelastic scattering to the 0(2)(+) state of C-12, the Hoyle state, in a fully microscopic framework. With no free adjustable parameter, the inelastic cross sections at forward angles are well reproduced by the microscopic reaction calculation using the transition density of C-12 obtained by the resonating group method and the nucleon-nucleon g matrix interaction developed by the Melbourne group. It is thus shown that the monopole transition strength obtained by the structural calculation is consistent with that extracted from the reaction observable, suggesting no missing monopole strength of the Hoyle state.

DOI： 10.1103/PhysRevC.93.051601

Language：English   Publishing type：Research paper (scientific journal)  

We have measured the azimuthal anisotropy of neutrons emitted from the Fe-56(gamma, n)Fe-55 reaction with a linearly polarized gamma-ray beam generated by laser Compton scattering at NewSUBARU. Neutron yields at the polar angle of 90 degrees have been measured as a function of the azimuthal angle phi between the detector and the linear polarization plane of the gamma-ray beam. The azimuthal anisotropy of neutrons measured at phi = 0 degrees, 10 degrees, 25 degrees, 45 degrees, 60 degrees, 70 degrees, and 90 degrees has been well reproduced using a theoretically predicted function of a + b cos(2 phi).

DOI： 10.1103/PhysRevC.93.044313

Language：English   Publishing type：Research paper (scientific journal)  

Probing surface distributions of alpha clusters in Ne-20 via alpha-transfer reaction
Background: Direct evidence of the alpha-cluster manifestation in bound states has not been obtained yet, although a number of experimental studies were carried out to extract the information of the clustering. In particular in conventional analyses of alpha-transfer reactions, there exist a few significant problems on reaction models, which are insufficient to qualitatively discuss the cluster structure.Purpose: We aim to verify the manifestation of the alpha-cluster structure from observables. As the first application, we plan to extract the spatial information of the cluster structure of the Ne-20 nucleus in its ground state through the cross section of the alpha-transfer reaction O-16(Li-6, d)Ne-20.Methods: For the analysis of the transfer reaction, we work with the coupled-channel Born approximation (CCBA) approach, in which the breakup effect of Li-6 is explicitly taken into account by means of the continuum-discretized coupled-channel method based on the three-body alpha + d + O-16 model. The two methods are adopted to calculate the overlap function between Ne-20 and alpha + O-16; one is the microscopic cluster model (MCM) with the generator coordinate method, and the other is the phenomenological two-body potential model ( PM).Results: We show that the CCBA calculation with the MCM wave function gives a significant improvement of the theoretical result on the angular distribution of the transfer cross section, which is consistent with the experimental data. Employing the PM, it is discussed which region of the cluster wave function is probed on the transfer cross section.Conclusions: It is found that the surface region of the cluster wave function is sensitive to the cross section. The present work is situated as the first step in obtaining important information to systematically investigate the cluster structure.

DOI： 10.1103/PhysRevC.93.034606

Language：English   Publishing type：Research paper (scientific journal)  

We analyze O-16-O-16 and C-12-C-12 scattering with themicroscopic coupled-channels method and investigate the coupled-channels and three-nucleon-force (3NF) effects on elastic and inelastic cross sections. In the microscopic coupled-channels calculation, the Melbourne g-matrix interaction modified according to the chiral 3NF effects is used. It is found that the coupled-channels and 3NF effects additively change both the elastic and inelastic cross sections. As a result, the coupled-channels calculation including the 3NF effects significantly improves the agreement between the theoretical results and the experimental data. The incident-energy dependence of the coupled-channels and 3NF effects is also discussed.

DOI： 10.1103/PhysRevC.93.014607

Language：English   Publishing type：Research paper (scientific journal)  

We analyze Li6 elastic scattering in a wide range of incident energies (Ein), assuming the n+p+α+target four-body model and solving the dynamics with the four-body version of the continuum-discretized coupled-channels method (CDCC). Four-body CDCC reproduces the experimental data well with no adjustable parameter for Li6+Bi209 scattering at Ein=24-50 MeV and Li6+Pb208 scattering at Ein=29-210 MeV. In the wide Ein range, Li6 breakup is significant and provides repulsive corrections to the folding potential. In Li6 elastic scattering, as an interesting property, Li6 is mainly broken up into two particles d and α, and hardly into three particles n, p, and α. We investigate what causes this dα dominance.

DOI： 10.1103/PhysRevC.92.044611

Language：English   Publishing type：Research paper (scientific journal)  

We analyze Li-6 elastic scattering in a wide range of incident energies (E-in), assuming the n + p + alpha + target four-body model and solving the dynamics with the four-body version of the continuum-discretized coupled-channels method (CDCC). Four-body CDCC reproduces the experimental data well with no adjustable parameter for Li-6 + Bi-209 scattering at E-in = 24-50 MeV and Li-6 + Pb-208 scattering at E-in = 29-210 MeV. In the wide E-in range, Li-6 breakup is significant and provides repulsive corrections to the folding potential. In Li-6 elastic scattering, as an interesting property, Li-6 is mainly broken up into two particles d and alpha, and hardly into three particles n, p, and alpha. We investigate what causes this d alpha dominance.

DOI： 10.1103/PhysRevC.92.044611

Language：English   Publishing type：Research paper (scientific journal)  

The parallel momentum distribution (PMD) of the residual nuclei of the O-14(p, pn)O-13 and O-14(p, 2p)N-13 reactions at 100 and 200 MeV/nucleon in inverse kinematics is investigated with the framework of the distorted-wave impulse approximation. The PMD shows an asymmetric shape characterized by a steep falloff on the high momentum side and a long-ranged tail on the low momentum side. The former is found to be due to the phase volume effect reflecting the energy and momentum conservation, and the latter is to the momentum shift of the outgoing two nucleons inside an attractive potential caused by the residual nucleus. Dependence of these effects on the nucleon separation energy of the projectile and the incident energy is also discussed.

DOI： 10.1103/PhysRevC.92.034616

Language：English   Publishing type：Research paper (scientific journal)  

We investigate the effects of chiral three-nucleon force (3NF) on proton scattering at 65 MeV and He-4 scattering at 72 MeV/nucleon from heavier targets, using the standard microscopic framework composed of the Brueckner-Hartree-Fock (BHF) method and the g-matrix folding model. For nuclear matter, the g matrix is evaluated from chiral two-nucleon force (2NF) of (NLO)-L-3 and chiral 3NF of NNLO by using the BHF method. Because the g matrix thus obtained is numerical and nonlocal, an optimum local form is determined from the on-shell and near-on-shell components of g matrix that are important for elastic scattering. For elastic scattering, the optical potentials are calculated by folding the local chiral g matrix with projectile and target densities. This microscopic framework reproduces the experimental data without introducing any adjustable parameter. Chiral-3NF effects are small for proton scattering, but sizable for He-4 scattering at middle angles where the data are available. Chiral 3NF, mainly in the 2 pi-exchange diagram, makes the folding potential less attractive and more absorptive for all the scattering.

DOI： 10.1103/PhysRevC.92.024618

Language：English  

Breakup and finite-range effects on the 8B(d,n)9C reaction

Language：English  

Systematic Analysis for Distribution of Extra Neutrons and Core in Halo Nucleus

Language：English  

Dynamical Studies of the Formation and Decay of Particle-Unbound States

Language：Others   Publishing type：Research paper (other academic)  

DOI： 10.7566/jpscp.6.020037

Language：English   Publishing type：Research paper (scientific journal)  

The astrophysical factor of B-8(p, gamma)C-9 at zero energy, S-18(0), is determined by a three-body coupled-channels analysis of the transfer reaction B-8(d, n)C-9 at 14.4 MeV/nucleon. Effects of the breakup channels of d and C-9 are investigated with the continuum-discretized coupled-channels method. It is found that, in the initial and final channels, respectively, the transfer process through the breakup states of d and C-9, its interference with that through their ground states in particular, gives a large increase in the transfer cross section. The finite-range effects with respect to the proton-neutron relative coordinate are found to be about 20%. As a result of the present analysis, S-18(0) = 22 +/- 6 eVb is obtained, which is smaller than the result of the previous distorted-wave Born approximation analysis by about 51%.

DOI： 10.1103/PhysRevC.91.014604

Language：English   Publishing type：Research paper (scientific journal)  

In 1957, Agodi predicted that the neutron angular distribution in (gamma, n) reactions with a 100% linearly polarized gamma-ray beam for dipole excitation should be anisotropic and universally described by the simple function of a + b . cos(2 phi) at the polar angle theta = 90 degrees, where phi is the azimuthal angle. However, this prediction has not been experimentally confirmed in over half a century. We have verified experimentally this angular distribution in the (gamma, n) reaction for Au-197, I-127, and natural Cu targets using linearly polarized laser Compton scattering gamma-rays. The result suggests that the ((gamma) over right arrow, n) reaction is a novel tool to study nuclear physics in the giant dipole resonance region. (C) 2014 The Authors. Published by Elsevier B.V.

DOI： 10.1016/j.physletb.2014.08.024

Language：English   Publishing type：Research paper (scientific journal)  

Extensions of the eikonal approximation to low energy (20 MeV/nucleon typically) are studied. The relation between the dynamical eikonal approximation (DEA) and the continuum-discretized coupled-channels method with the eikonal approximation (E-CDCC) is discussed. When Coulomb interaction is artificially turned off, DEA and E-CDCC are shown to give the same breakup cross section, within 3% error, of C15 on Pb208 at 20 MeV/nucleon. When the Coulomb interaction is included, the difference is appreciable and none of these models agrees with full CDCC calculations. An empirical correction significantly reduces this difference. In addition, E-CDCC has a convergence problem. By including a quantum-mechanical correction to E-CDCC for lower partial waves between C15 and Pb208, this problem is resolved and the result perfectly reproduces full CDCC calculations at a lower computational cost.

DOI： 10.1103/PhysRevC.90.034617

Language：English   Publishing type：Research paper (scientific journal)  

Extensions of the eikonal approximation to low energy (20 MeV/nucleon typically) are studied. The relation between the dynamical eikonal approximation (DEA) and the continuum-discretized coupled-channels method with the eikonal approximation (E-CDCC) is discussed. When Coulomb interaction is artificially turned off, DEA and E-CDCC are shown to give the same breakup cross section, within 3% error, of C-15 on Pb-208 at 20 MeV/nucleon. When the Coulomb interaction is included, the difference is appreciable and none of these models agrees with full CDCC calculations. An empirical correction significantly reduces this difference. In addition, E-CDCC has a convergence problem. By including a quantum-mechanical correction to E-CDCC for lower partial waves between C-15 and Pb-208, this problem is resolved and the result perfectly reproduces full CDCC calculations at a lower computational cost.

DOI： 10.1103/PhysRevC.90.034617

Language：English   Publishing type：Research paper (scientific journal)  

The eikonal reaction theory (ERT) proposed lately is a method of calculating one-neutron removal reactions at intermediate incident energies in which Coulomb breakup is treated accurately with the continuum discretized coupled-channels method. ERT is extended to two-neutron removal reactions. ERT reproduces measured one-and two-neutron removal cross sections for He-6 scattering on C-12 and Pb-208 targets at 240 MeV/nucleon and also on a Si-28 target at 52 MeV/nucleon. For the heavier target in which Coulomb breakup is important, ERT yields much better agreement with the measured cross sections than the Glauber model.

DOI： 10.1103/PhysRevC.90.027601

Language：English   Publishing type：Research paper (scientific journal)  

We discuss how to extract an electric dipole (E1) breakup cross section sigma(E1) from one- neutron removal cross sections measured at 250 MeV/nucleon by using C-12 and Pb-208 targets, sigma(C)(-1n) and sigma(Pb)(-1n), respectively. It is shown that, within about 5% error, sigma(E1) can be obtained by subtracting Gamma sigma(C)(-1n) from sigma(Pb)(-1n), as assumed in preceding studies. However, for the reaction of weakly bound projectiles, the scaling factor Gamma is found to be about twice as large as that usually adopted. As a result, we obtain a 13- 20% smaller sigma(E1) of Ne-31 at 250 MeV/nucleon than extracted in a previous analysis of experimental data. By compiling the values of Gamma obtained for several projectiles, Gamma = (2.30 +/- 0.41) exp(-S-n) + (2.43 +/- 0.21) is obtained, where S-n is the neutron separation energy. The target mass- number dependence of the nuclear parts of the one- neutron removal cross section and the elastic breakup cross section is also investigated.

DOI： 10.1093/ptep/ptu063

Language：English   Publishing type：Research paper (scientific journal)  

Nucleon-induced reactions on Li-6,Li-7 are analyzed systematically over a wide range of incident energies up to 150 MeV by using three-body continuum discretized coupled channels method (CDCC) capable of treating the breakup of Li-6,Li-7. The diagonal and coupling potentials in the CDCC equation are obtained by folding the complex Jeukenne-Lejeune-Mahaux effective nucleon-nucleon interaction with transition densities. The normalization factors of the complex effective interaction are determined so as to reproduce experimental data on neutron total and proton reaction cross sections. Triton emission from Li-7 breakup channel and p(n)+Li-7 -> t+Li-5*(He-5*) channel is analyzed by the sequential decay model and final state interaction model, respectively. In most cases, the calculated results are in good agreement with experimental data except for the nucleon production double differential cross sections (DDX) at relatively low emission energies.

DOI： 10.1016/j.nds.2014.04.051

Language：English   Publishing type：Research paper (scientific journal)  

We have extended the CCONE code to make it possible to calculate cross sections for deuteron-induced reactions. Elastic breakup and stripping reactions to continuum are calculated using another codes based on the Continuum-Discretized Coupled-Channels theory (CDCC) and the Glauber model, respectively, and the calculated results are inputted to the CCONE code as direct reaction components. Statistical decay from compound nuclei formed by nucleon stripping and deuteron absorption is calculated with the exciton and Hauser-Feshbach models implemented in the original CCONE code. The extended CCONE code is applied to analyses of deuteron-induced reactions on Al-27 and Ni-58. CDCC calculations for deuteron elastic scattering show good agreement with the experimental data at incident energies of several tens of MeV. The calculated double-differential (d, xp) cross sections reproduce the measured ones at forward angles for incident energies of 56 and 100 MeV fairly well.

DOI： 10.1016/j.nds.2014.04.065

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The proton inelastic scattering of O-24( p, p') at 62 MeV/ nucleon is described by a self-consistent microscopic calculation with the continuum particle-vibration coupling (cPVC) method. The SLy5, SkM*, and SGII parameters are adopted as alternative effective nucleon-nucleon interactions. For all the Skyrme parameters the cPVC calculation reproduces reasonably well the absolute values of the first and second peaks of the excitation energy spectrum of 24O and the absolute value of the angular distribution corresponding to the first peak at 4.65 MeV. The relative energy between the two peaks is well reproduced by the cPVC method with SLy5 and SkM*. The role of the cPVC self-energy strongly depends on the effective interactions. The second peak around 7.3 MeV is suggested to be a superposition of the 3(-) and 4(+) states by the results with SLy5 and SGII, whereas the SkM* calculation indicates it is a pure 3- state. This difference gives a rather strong interaction dependence of the angular distribution corresponding to the second peak.

DOI： 10.1103/PhysRevC.89.034620

Language：English   Publishing type：Research paper (scientific journal)  

We have measured the O-16(p,d) reaction using 198-, 295- and 392-MeV proton beams to search for a direct evidence on an effect of the tensor interactions in light nucleus. Differential cross sections of the one-neutron transfer reaction populating the ground states and several low-lying excited states in O-15 were measured. Comparing the ratios of the cross sections for each excited state to the one for the ground state over a wide range of momentum transfer, we found a marked enhancement of the ratio for the positive-parity state(s). The observation is consistent with large components of high-momentum neutrons in the initial ground-state configurations due to the tensor interactions. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physletb.2013.07.038

Language：English   Publishing type：Research paper (scientific journal)  

The astrophysical factor of the B-8(p, gamma )C-9 reaction at zero energy, S (18)(0), is determined from three-body model analysis of C-9 breakup processes. The elastic breakup Pb-208(C-9,p B-8)Pb-208 at 65 MeV/nucleon and the one-proton removal reaction of C-9 at 285 MeV/nucleon on C and Al targets are calculated with the continuum-discretized coupled-channels method (CDCC) and the eikonal reaction theory (ERT), respectively. As a result of the present analysis, S (18)(0) extracted from the two reactions shows good consistency, in contrast to in the previous studies.

DOI： 10.1007/s00601-012-0580-2

Language：English   Publishing type：Research paper (scientific journal)  

Decay mode of the 2(1)(+) resonant state of He-6 populated by the He-6 breakup reaction by C-12 at 240 MeV/nucleon is investigated. The continuum-discretized coupled-channels method is adopted to describe the formation of the 2(1)(+) state, whereas its decay is described by the complex-scaled solutions of the Lippmann-Schwinger equation. From analysis of invariant mass spectra with respect to the alpha-n and n-n subsystems, coexistence of two decay modes is found. One is the simultaneous decay of two neutrons correlating with each other and the other is the emission of two neutrons to the opposite directions. The latter is found to be free from the final-state interaction and suggests existence of a dineutron in the 2(1)(+) state of He-6.

DOI： 10.1103/PhysRevC.88.021602

Language：English   Publishing type：Research paper (scientific journal)  

Decay mode of the 21+ resonant state of 6He populated by the 6He breakup reaction by 12C at 240 MeV/nucleon is investigated. The continuum-discretized coupled-channels method is adopted to describe the formation of the 21+ state, whereas its decay is described by the complex-scaled solutions of the Lippmann-Schwinger equation. From analysis of invariant mass spectra with respect to the α-n and n-n subsystems, coexistence of two decay modes is found. One is the simultaneous decay of two neutrons correlating with each other and the other is the emission of two neutrons to the opposite directions. The latter is found to be free from the final-state interaction and suggests existence of a dineutron in the 21+ state of 6He. © 2013 American Physical Society.

DOI： 10.1103/PhysRevC.88.021602

Language：English   Publishing type：Research paper (scientific journal)  

The triple alpha reaction rate in stars is quite important in many astrophysical scenarios including the stellar evolution and carbon synthesis in stars. Recently the non-resonant triple alpha reaction rate has been reevaluated using a calculation with the continuum-discretized coupled-channels (CDCC) method, which dramatically increased the rate at low temperature compared to the widely-used NACRE compilation. Since the enhancement influences strongly on astrophysical model simulations, we have planned an experiment for drawing conclusion on the non-resonant triple alpha reaction rate at low temperature by measuring the three-alpha continuum state in C-12. We report the present situation of the experiment.

DOI： 10.1007/s00601-013-0697-y

Language：English   Publishing type：Research paper (scientific journal)  

The breakup cross section (BUX) of C-22 by C-12 at 250 MeV/nucleon is evaluated by the continuum-discretized coupled-channels method incorporating the cluster-orbital shell model (COSM) wave functions. Contributions of the low-lying 0(2)(+) and 2(1)(+) resonances predicted by COSM to the BUX are investigated. The 2(1)(+) resonance gives a narrow peak in the BUX, as in usual resonant reactions, whereas the 0(2)(+) resonant cross section has a peculiar shape due to the coupling to the nonresonant continuum, i.e., the background-phase effect (BPE). By changing the scattering angle of C-22 after the breakup, a variety of shapes of the 0(2)(+) resonant cross sections are obtained. The mechanism of the appearance of the sizable BPE in the breakup of C-22 is discussed.

DOI： 10.1103/PhysRevC.88.024616

Language：English   Publishing type：Research paper (scientific journal)  

We present an accurate method of treating neutron removal reactions and it's applications. According to the method, the nuclear and Coulomb breakup processes are consistently treated by the method of the continuum discretized coupled channels. This method is referred to as the eikonal reaction theory (ERT). We analyze the two types of removal reactions of Ne-31 and He-6 with ERT.

DOI： 10.1007/s00601-012-0517-9

Language：English   Publishing type：Research paper (scientific journal)  

Nucleon scattering from 6,7Li is analyzed systematically over a wide range of incident energies up to 150 MeV with the continuum discretized coupled channels method (CDCC) capable of treating the breakup of 6 ,7Li. The continuum states of 6,7Li are discretized with the pseudostate method. Diagonal and coupling potentials in the CDCC equation are obtained by folding the complex Jeukenne-Lejeune-Mahaux effective nucleon-nucleon interaction with transition densities between corresponding bound and discretized continuum states of 6,7Li. The normalization factors of the complex effective interaction are determined so as to reproduce experimental data on neutron total and proton reaction cross sections for 6 ,7Li. CDCC calculations with the normalization factors reproduce experimental differential cross sections for nucleon elastic and inelastic scattering from 6,7Li well. © 2013 American Physical Society.

DOI： 10.1103/PhysRevC.87.024610

Language：English   Publishing type：Research paper (scientific journal)  

Nucleon scattering from Li-6,Li-7 is analyzed systematically over a wide range of incident energies up to 150 MeV with the continuum discretized coupled channels method (CDCC) capable of treating the breakup of Li-6,Li-7. The continuum states of Li-6,Li-7 are discretized with the pseudostate method. Diagonal and coupling potentials in the CDCC equation are obtained by folding the complex Jeukenne-Lejeune-Mahaux effective nucleon-nucleon interaction with transition densities between corresponding bound and discretized continuum states of Li-6,Li-7. The normalization factors of the complex effective interaction are determined so as to reproduce experimental data on neutron total and proton reaction cross sections for Li-6,Li-7. CDCC calculations with the normalization factors reproduce experimental differential cross sections for nucleon elastic and inelastic scattering from Li-6,Li-7 well. DOI: 10.1103/PhysRevC.87.024610

DOI： 10.1103/PhysRevC.87.024610

Language：Others  

Language：English  

Four-body CDCC analysis for breakup reactions of three-body projectiles

Language：English  

Study of the tensor correlation in 4He via the 4He(p, dp)d and 4He(p, dp)pn reactions

Language：English   Publishing type：Research paper (scientific journal)  

The microscopic description of neutron scattering by O-16 below 30 MeV is carried out by means of the continuum particle-vibration coupling (cPVC) method with the Skyrme nucleon-nucleon (NN) effective interaction. In the cPVC method, a proper boundary condition on a nucleon in continuum states is imposed, which enables one to evaluate the transition matrix in a straightforward manner. Experimental data of the total and total-elastic cross sections are reproduced quite well by the cPVC method. An important feature of the result is the fragmentation of the single-particle resonance into many peaks as well as the shift of its centroid energy. Thus, some part of the fine structure of the experimental cross sections at lower energies is well described by the cPVC framework. The cPVC method based on a real NN effective interaction is found to successfully explain about 85% of the reaction cross section, through explicit channel-coupling effects.

DOI： 10.1103/PhysRevC.86.041603

Language：English   Publishing type：Research paper (scientific journal)  

We investigate projectile breakup effects on Li-6 + Bi-209 elastic scattering near the Coulomb barrier with the four-body version of the continuum-discretized coupled-channels method (four-body CDCC). The elastic scattering is well described by the p + n + He-4 + Bi-209 four-body model. Furthermore, we propose a reasonable d + He-4 + Bi-209 three-body model for describing the four-body scattering, clarifying four-body dynamics of the elastic scattering.

DOI： 10.1103/PhysRevC.86.031601

Language：English   Publishing type：Research paper (scientific journal)  

The astrophysical factor of B-8(p,gamma)C-9 at zero energy, S-18(0), is determined from three-body model analysis of C-9 breakup processes. The elastic breakup reaction Pb-208(C-9,p(8)B)Pb-208 at 65 MeV/nucleon and the one-proton removal reaction of C-9 at 285 MeV/nucleon on C and Al targets are calculated with the continuumdiscretized coupled-channels method (CDCC) and the eikonal reaction theory (ERT), respectively. The asymptotic normalization coefficient (ANC) of C-9 in the p-B-8 configuration, C-p8B(9C), extracted from the two reactions shows good consistency, unlike in previous studies. As a result of the present analysis, S-18(0) = 66 +/- 10 eVb is obtained.

DOI： 10.1103/PhysRevC.86.022801

Language：English   Publishing type：Research paper (scientific journal)  

Deformations of Ne isotopes in the island of inversion are determined by the folding model description of the interaction cross sections measured for 28-32Ne isotopes incident on a 12C target at 240 MeV/nucleon, using the Melbourne g-matrix interaction and the nuclear densities calculated by antisymmetrized molecular dynamics (AMD). The double folding model with the AMD density well reproduces the measured interaction cross sections, if the tail correction is made to the AMD density for 31Ne. The quadrupole deformation determined is around 0.4 in the island of inversion and 31Ne is a halo nucleus with large deformation. We propose the Woods-Saxon model with the AMD deformation and a suitably chosen parametrization set as an approximate but simple method to reproduce the AMD density with the tail correction. The angular momentum projection is essential to obtain the large deformation in the island of inversion. Effects of the pairing correlation are investigated. © 2012 American Physical Society.

DOI： 10.1103/PhysRevC.85.064613

Language：English   Publishing type：Research paper (scientific journal)  

Deformations of Ne isotopes in the island of inversion are determined by the folding model description of the interaction cross sections measured for Ne28-32 isotopes incident on a C-12 target at 240 MeV/nucleon, using the Melbourne g-matrix interaction and the nuclear densities calculated by antisymmetrized molecular dynamics (AMD). The double folding model with the AMD density well reproduces the measured interaction cross sections, if the tail correction is made to the AMD density for Ne-31. The quadrupole deformation determined is around 0.4 in the island of inversion and Ne-31 is a halo nucleus with large deformation. We propose the Woods-Saxon model with the AMD deformation and a suitably chosen parametrization set as an approximate but simple method to reproduce the AMD density with the tail correction. The angular momentum projection is essential to obtain the large deformation in the island of inversion. Effects of the pairing correlation are investigated.

DOI： 10.1103/PhysRevC.85.064613

Language：English   Publishing type：Research paper (scientific journal)  

Determination of the structure of 31Ne by a fully microscopic framework

Language：English   Publishing type：Research paper (scientific journal)  

Inclusive proton emissions from deuteron-induced reactions on Be-9, C-12, Al-27, Ni-58, Nb-93, Ta-181, Pb-208, and U-238 at an incident energy of 100 MeV are analyzed using the continuum discretized coupled-channels theory for the elastic-breakup process and the Glauber model for the neutron-stripping process in order to investigate deuteron-breakup processes over a wide range of target mass numbers. The effects of Coulomb interactions are taken into account to give a proper description of proton emissions at forward angles. Moreover, the phenomenological moving-source model is used to estimate evaporation and preequilibrium components in inclusive (d, xp) spectra. The calculation reproduces fairly well a prominent bump observed around half the incident energy in experimental (d, xp) spectra for light and medium nuclei at forward angles of less than 20 degrees whereas the calculation underestimates the bump component as the target atomic number increases. The underestimation is likely due to the fact that the eikonal approximation used in the Glauber model becomes worse due to strong Coulomb interactions. It is shown that the Glauber-model calculation for the neutron-stripping process leads to an improvement of this discrepancy by substituting the eikonal phase shift for the quantum phase shift given by the optical-model calculation.

DOI： 10.1103/PhysRevC.84.054606

Language：English   Publishing type：Research paper (scientific journal)  

The continuum-discritized coupled channel method and the glauber model are applied for the description of deuteron elastic breakup and the stripping processes, respectively. Combined with the conventional two-component exciton model for pre-equilibrium processes and the Hauser-Feshbach theory for compound process, an approach based on models is proposed to analyze the inclusive proton energy spectra of a deuteron-induced reaction. The contributions from each process to the energy spectra of the Ni-58(d,xp) reaction are quantitatively given. The results show that this approach is able to reasonably reproduce the experimental data of the double differential cross sections, energy spectra and cross sections, although further improvements are needed.

DOI： 10.1088/0256-307X/28/11/112401

Language：English   Publishing type：Research paper (scientific journal)  

The differential cross sections of two-nucleon transfer reactions U-238(O-18,O-16)U-240 around 180 MeV are calculated by one-step Born approximation with a O-16+(2)n+U-238 three-body model. The wave function in the initial channel is obtained by the continuum-discretized coupled-channels method, and that in the final channel is evaluated by adiabatic approximation. The cross sections have a peak around the grazing angle, and the spin distribution, i.e., the cross section at the peak as a function of the transferred spin, is investigated. The shape of the spin distribution is found to be not sensitive to the incident energies, optical potentials, and treatment of the breakup channels, whereas it depends on the excitation energy of the residual nucleus U-240. To fulfill the condition that the peak position should not exceeds 10 (h) over bar, which is necessary for the surrogate ratio method to work, it is concluded that the excitation energy must be less than 10 MeV.

DOI： 10.3327/jnst.48.1337

Language：English   Publishing type：Research paper (scientific journal)  

The isotope dependence of measured reaction cross sections in the scattering of (28) Ne-32 isotopes from a C-12 target at 240 MeV/nucleon is analyzed by the double-folding model with the Melbourne g matrix. The density of the projectile is calculated by the mean-field model with the deformed Woods-Saxon potential. The deformation is evaluated by antisymmetrized molecular dynamics. The deformation of the projectile enhances calculated reaction cross sections to the measured values.

DOI： 10.1103/PhysRevC.84.034602

Language：English   Publishing type：Research paper (scientific journal)  

A model calculation is applied for analyses of nucleon production from deuteron breakup reactions for energies up to 100 MeV, in which elastic breakup process and inelastic breakup process (stripping) are described by the continuum discretized coupled-channels method and the Glauber model, respectively. The effects of Coulomb interaction are taken in to account to give a proper description of nucleon production at forward angles. In addition to these two direct processes, the evaporation and pre-equilibrium processes are described by the moving source model which contributes mainly to the low energy nucleon emissions. The deuteron breakup reactions are investigated systematically through the present analyses

DOI： 10.3938/jkps.59.871

Language：English   Publishing type：Research paper (scientific journal)  

We present an accurate method of treating the one-neutron removal reaction at intermediate incident energies induced by both nuclear and Coulomb interactions. In the method, the nuclear and Coulomb breakup processes are consistently treated by the method of continuum discretized coupled channels without making the adiabatic approximation to the Coulomb interaction, so that the removal cross section calculated never diverges. This method is applied to a recently measured one-neutron removal cross section for (31)Ne+(12)C scattering at 230 MeV/nucleon and (31)Ne+(208)Pb scattering at 234 MeV/nucleori. The spectroscopic factor and asymptotic normalization coefficient of the last neutron in (31)Ne are evaluated.

DOI： 10.1143/PTP.126.167

Language：English   Publishing type：Research paper (scientific journal)  

Subbarrier alpha transfer reaction (13)C((6)Li, d)(17)O(6.356 MeV, 1/2(+)) at 3.6 MeV is analyzed with an alpha + d+(13)C three-body model, and the asymptotic normalization coefficient (ANC) for alpha+(13)C -> (17)O(6.356 MeV, 1/2+), which essentially determines the reaction rate of (13)C(alpha,n)(16)O, is extracted. Breakup effects of (6)Li in the initial channel and those of (17)O in the final channel are investigated with the continuum-discretized coupled-channels method (CDCC). The former is found to have a large back-coupling to the elastic channel, whereas the latter turns out to be significantly small. The transfer cross section calculated with Born approximation to the transition operator, including breakup states of (6)Li, gives (C(alpha 13C)(17)O*)(2) = 1.03 +/- 0.29 fm(-1). This result is consistent with the value obtained by the previous DWBA calculation.

DOI： 10.1143/PTP.125.1193

Language：English   Publishing type：Research paper (scientific journal)  

The continuum-discretized coupled-channels method (CDCC) for exclusive reactions and the eikonal reaction theory (ERT) as an extension of CDCC to inclusive reactions are applied to deuteron-induced reactions. The CDCC result reproduces experimental data on the reaction cross section for d + Ni-58 scattering at 200 MeV/nucleon, and ERT provides data on the neutron-stripping cross section for inclusive Li-7(d, n) reaction at 40 MeV. For deuteron-induced reactions at 200 MeV/nucleon, target-dependence of the reaction, elastic-breakup, nucleon-stripping, nucleon-removal, and complete-and incomplete-fusion cross sections is clearly explained by simple formulas. Accuracy of the Glauber model is also investigated.

DOI： 10.1103/PhysRevC.83.054617

Language：English   Publishing type：Research paper (scientific journal)  

The nonlocality of the microscopic nucleon-nucleus optical potential is commonly localized by the Brieva-Rook approximation. The validity of the localization is tested for the proton+(90)Zr scattering at incident energies from 65 MeV to 800 MeV. The localization is valid in a wide incident-energy range.

DOI： 10.1088/0954-3899/37/8/085011

Language：English   Publishing type：Research paper (scientific journal)  

This article is composed of three subjects. First, the relation between the method of continuum-discretized coupled channels (CDCC) and the Faddeev theory is clarified to show the validity of CDCC. Second, CDCC is applied to four-body reactions such as (He-6, nn(4)He) as an example of recent progress in CDCC. Third, we propose a microscopic version of CDCC in which a localized form of the microscopic nucleon-nucleus optical potential is used as an input of CDCC calculation instead of the phenomenological optical potential commonly used. The validity of the Brieva-Rook localization is shown for the proton scattering in a wide incident-energy range

DOI： 10.1142/S0217732310000253

Language：English  

DOI： 10.1143/PTP.123.921

Language：English   Publishing type：Research paper (scientific journal)  

The continuum-discretized coupled-channels (CDCC) method is used to study the breakup of weakly-bound nuclei at intermediate energies collisions. For large impact parameters, the Eikonal CDCC (E-CDCC) method was applied. The effects of Lorentz contraction on the nuclear and Coulomb potentials have been investigated in details. Such effects tend to increase cross sections appreciably. We also show that, for loosely-bound nuclei, the contribution of the so-called close field is small and can be neglected.

DOI： 10.1143/PTP.123.701

Language：English   Publishing type：Research paper (scientific journal)  

Reaction cross sections (sigma(R)) for C-19, C-20 and the drip-line nucleus C-22 on a liquid hydrogen target have been measured at around 40A MeV by a transmission method. A large enhancement of sigma(R) for C-22 compared to those for neighboring C isotopes was observed. Using a finite-range Glauber calculation under an optical-limit approximation the rms matter radius of C-22 was deduced to be 5.4 +/- 0.9 fm. It does not follow the systematic behavior of radii in carbon isotopes with N <= 14, suggesting a neutron halo. It was found by an analysis based on a few-body Glauber calculation that the two-valence neutrons in C-22 preferentially occupy the 1s(1/2) orbital.

DOI： 10.1103/PhysRevLett.104.062701

Language：English   Publishing type：Research paper (scientific journal)  

We propose a new method for evaluating incomplete and complete fusion cross sections separately using the Continuum-Discretized Coupled-Channels method. This method is applied to analysis of the deuteron induced reaction on a (7)Li target Up to 50 MeV of the deuteron incident energy. Effects of deuteron breakup on this reaction are explicitly taken into account. Results of the method are compared with those of the Glauber model, and the difference between the two is discussed. It is found that the energy dependence of the incomplete fusion cross sections obtained by the present calculation is almost the same as that obtained by the Glauber model, while for the complete fusion cross section, the two models give markedly different energy dependence. We show also that a prescription for evaluating incomplete fusion cross sections proposed in a previous study gives Much smaller result than an experimental value.

DOI： 10.1143/PTP.122.1291

Language：English   Publishing type：Research paper (scientific journal)  

Triple-alpha reaction rate is re-evaluated by directly solving the three-body Schrodinger equation. The resonant and nonresonant processes are treated on the same footing using the continuum-discretized coupled-channels method for three-body scattering. An accurate description of the alpha-alpha nonresonant states significantly quenches the Coulomb barrier between the first two alpha-particles and the third alpha-particle. Consequently, the alpha-alpha nonresonant continuum states below the resonance at 92.04 keV, i.e., the ground state of (8)Be, give a markedly larger contribution at low temperatures than that reported in previous studies. We show that Nomoto's method for three-body nonresonant capture processes, which is adopted in the NACRE compilation and many other studies, is a crude approximation of the accurate quantum three-body model calculation. We find an increase in triple-alpha reaction rate by about 20 orders of magnitude around 10(7) K compared with the rate of NACRE.

DOI： 10.1143/PTP.122.1055

Language：English   Publishing type：Research paper (scientific journal)  

The dependence of breakup cross sections of B-8 at 65 MeV/nucleon on the target mass number AT is investigated by means of the continuum-discretized coupled-channels method (CDCC) with more reliable distorting potentials than those in the preceding study. The A(T)(1/3) scaling law of the nuclear breakup cross section is found to be satisfied only in the middle AT region of 40 less than or similar to A(T) less than or similar to 150. The interference between nuclear and Coulomb breakup amplitudes vanishes in very forward angle scattering, independently of the target nucleus. The truncation of the relative energy between the p and Be-7 fragments slightly reduces the contribution of nuclear breakup at very forward angles, while the angular region in which the first-order perturbation theory works well does not change essentially.

DOI： 10.1143/JPSJ.78.084201

Language：English   Publishing type：Research paper (scientific journal)  

Inclusive nucleon spectra from deuteron breakup reactions on Li-7 are analyzed in terms of the continuum discretized coupled channels theory for the elastic breakup process and the Glauber model for the nucleon stripping process. Both theoretical models use the same phenomenological nucleon optical potential of Li-7 and have no other free parameters. The calculations reproduce well a prominent bump observed around half the incident energy in experimental inclusive spectra of 40-MeV (d,xn) and 100-MeV (d,xp) reactions at forward angles. The analysis shows that the stripping process is more important than the elastic breakup process in deuteron breakup reactions on Li-7.

DOI： 10.1103/PhysRevC.80.014604

Language：English   Publishing type：Research paper (scientific journal)  

Relativistic effects in the breakup of weakly-bound nuclei at intermediate energies are studied by means of the continuum-discretized coupled-channels method with eikonal approximation. Nuclear coupling potentials with Lorentz contraction are newly included and those effects on breakup cross sections are investigated. We show that relativistic corrections lead to larger breakup cross sections. Coupled-channel effects on the breakup cross sections are also discussed.

DOI： 10.1143/PTP.121.1399

Language：English   Publishing type：Research paper (scientific journal)  

We present analyses of breakup effects of He-6 on the elastic scattering by the continuum-discretized coupled-channels method, in which the reaction system is described as a four-body model, center dot+center dot+He-4+target. In this analysis, three-body breakup continuum of 6He is discretized by daiagonalizing the internal Hamiltonian of He-6 in a space spanned by the Gaussian basis functions. The calculated elastic cross sections are in good agreement with the experimental data, which shows that nuclear and Coulomb breakup effects are significant.

Language：English   Publishing type：Research paper (scientific journal)  

We present a practical way of smoothing discrete breakup S-matrix elements calculated by the continuum-discretized coupled-channel method (CDCC). This method makes the smoothing procedure much easier. The reliability of the smoothing method is confirmed for two three-body breakup reactions, (58)Ni(d, pn) at 80 MeV and (12)C((6)He, (4)He(2) n) at 229.8 MeV.

DOI： 10.1143/PTP.121.885

Language：English   Publishing type：Research paper (scientific journal)  

We present a method of smoothing discrete breakup S-matrix elements calculated by the method of continuum-discretized coupled-channels (CDCC). This smoothing method makes it possible to apply CDCC to four-body breakup reactions. The reliability of the smoothing method is confirmed for two cases, Ni-58(d, pn) at 80 MeV and the El transition of He-6. We apply CDCC with the smoothing method to a He-6 breakup reaction at 22.5 MeV. Multistep breakup processes are found to be important.

DOI： 10.1143/PTP.121.789

Language：English   Publishing type：Research paper (scientific journal)  

We have studied the one-neutron removal reactions of C-18 at 81 MeV/nucleon and C-19 at 68 MeV/nucleon on a liquid hydrogen target. Transverse-momentum distributions of the core fragments C-17 and C-18, and their partial cross sections, are measured using coincidences with the. rays. These are compared to theoretical calculations based on the continuum-discretized coupled-channels (CDCC) method. We have found that the transverse-momentum distributions of 17C are well described by the CDCC calculations, and the agreement provides evidence for the spin-parity assignments of J(pi) = 1/2(+) for the 0.21-MeV state and J(pi) = 5/2(+) for the 0.33-MeV state in C-17. The J(pi) = (2, 3)(+) assignment for the 4.0-MeV state in C-18 is obtained for the first time based on the momentum distribution of C-18. The measured partial cross sections are consistent with the CDCC calculations combined with shell-model spectroscopic factors. The present study demonstrates that the transverse-momentum distribution obtained in a one-neutron removal reaction on a proton target is as useful as the conventional longitudinal-momentum distribution measured with the heavier Be or C targets for determining the orbital angular momentum of a removed neutron.

DOI： 10.1103/PhysRevC.79.014602

Language：English   Publishing type：Research paper (scientific journal)  

Glauber theory for nucleus-nucleus scattering at high incident energies is reformulated so as to also be applicable to the scattering at intermediate energies. We test the validity of the eikonal and adiabatic approximations used in the formulation, and discuss the relationship between the present theory and the conventional Glauber calculations using either the empirical nucleon-nucleon profile function or the modified one including the in-medium effect.

DOI： 10.1143/PTP.120.767

Language：English   Publishing type：Research paper (scientific journal)  

The continuum discretized coupled channels (CDCC) approach is applied to analysis of deuteron elastic scattering from Li-6,Li-7 in the energy range from 10 to 50 MeV. Phenomenological neutron and proton optical potentials that are essentially important in the CDCC calculation are determined from the present optical model analysis of differential cross sections of nucleon elastic scattering, neutron total cross sections, and reaction cross sections of Li-6,Li-7 for energies from 5 to 50 MeV. The CDCC result provides satisfactory agreement with experimental data, particularly at forward angles. The obtained nucleon optical model potentials are found to describe reasonably well both nucleon and deuteron elastic scattering from Li-6,Li-7 for energies up to 50 MeV.

DOI： 10.1103/PhysRevC.78.024611

Language：English   Publishing type：Research paper (scientific journal)  

The inclusive K+ momentum spectrum in the C-12(K-, K+) reaction is calculated by the semiclassical distorted wave (SCDW) model, including the transition to the Xi(-) bound state. We compare the calculated results with those of the previous analysis with Green's function method and those with the intra-nuclear cascade (INC) model, and examine the validity of the assumptions made in those analyses. It is found that an appropriate treatment of the kinematics of the elementary process in the nucleus is very important. The calculated spectra with the strength of the Xi(-) -nucleus potential -50, -20 and + 10 MeV are compared with the experimental data measured at High Energy Accelerator Research Organization (KEK) with p(k-) = 1.65 GeV/c. The shape of the measured spectrum is reproduced by the calculation and the inclusive spectrum changes systematically with the assumed strength of the Xi(-) -nucleus potential, while the calculated cross section underestimates the data. For more reliable analysis, we need experimental data of the (K-, K+) reaction as well as those of the elementary process with high accuracy.

DOI： 10.1143/PTP.119.1005

Language：English   Publishing type：Research paper (scientific journal)  

Recent development of the continuum-discretized coupled-channels method (CDCC) is reported with introducing the eikonal CDCC method (E-CDCC) and four-body CDCC. The former is applied to analysis of B-8 breakup by Pb-208 at 52 A MeV and the astrophysical factor S-17(0) for the Be-7(p, gamma)B-8 reaction is extracted with the asymptotic normalization coefficient method. We obtain S-17(0) = 20.9(-1.9)(+2.0) eV b, which is significantly larger than the previous one, S-17(0) 18.9 +/- 1.8 eV b, determined from an analysis with the virtual photon theory. The difference between the two values is found to be due to the contributions from nuclear breakup and higher-order processes. The latter, four-body CDCC, is applied to He-6+Bi-209 scattering near the Coulomb barrier energy and found to reproduce the elastic cross sections well, in contrast to the standard three-body CDCC. Accurate treatment of the three-body continuum states of He-6 turns out to be essential to correctly describe the He-6+Bi-209 scattering.

DOI： 10.1016/j.nuclphysa.2008.02.283

Language：English   Publishing type：Research paper (scientific journal)  

Semiclassical distorted-wave model analysis of the (pi(-),K+)Sigma formation inclusive spectrum
(pi(-),K+) hyperon production inclusive spectra with p(pi)=1.2 GeV/c measured at KEK on C-12 and Si-28 are analyzed by the semiclassical distorted-wave model. Single-particle (s.p.) wave functions of the target nucleus are treated using Wigner transformation. This method is able to account for the energy and angular dependences of the elementary process in nuclear medium without introducing the factorization approximation frequently employed. Calculations of the (pi(+),K+)Lambda formation process, for which there is no free parameter because the Lambda s.p. potential is known, demonstrate that the present model is useful to describe inclusive spectra. It is shown that to account for the experimental data of the Sigma(-) formation spectra a repulsive Sigma-nucleus potential is necessary whose magnitude is not so strong as around 100 MeV previously suggested.

DOI： 10.1103/PhysRevC.74.064613

Language：English   Publishing type：Research paper (scientific journal)  

We accurately analyze the He-6+Bi-209 scattering at 19 and 22.5 MeV near the Coulomb barrier energy, using the continuum-discretized coupled-channels (CDCC) method based on the n+n+ He-4+Bi-209 four-body model. The three-body breakup continuum of He-6 is discretized by diagonalizing the internal Hamiltonian of He-6 in a space spanned by the Gaussian basis functions. The calculated elastic and total reaction cross sections are in good agreement with the experimental data, whereas the CDCC calculation based on the dineutron model of He-6, that is, the (2)n+ He-4+Bi-209 three-body model, does not reproduce the data.

DOI： 10.1103/PhysRevC.73.051602

Language：English   Publishing type：Research paper (scientific journal)  

The astrophysical factor for Be-7(p,gamma)B-8 at zero energy, S-17(0), is determined from an analysis of Pb-208(B-8, p+Be-7)Pb-208 at 52 MeV/nucleon by means of the method of continuum-discretized coupled channels (CDCC) taking account of all nuclear and Coulomb breakup processes. The asymptotic normalization coefficient (ANC) method is used to extract S-17(0) from the calculated breakup cross section. The main result of the present paper is S-17(0)=20.9(-1.9)(+2.0) eV b. The error consists of 8.4% experimental systematic error and the error due to the ambiguity in the s-wave p-Be-7 scattering length. This value of S-17(0) differs from the one extracted with the first-order perturbation theory including Coulomb breakup by dipole transitions: 18.9 +/- 1.8 eV b. It turns out that the difference is due to the inclusion of the nuclear and Coulomb-quadrupole transitions and multistep processes of all-order in the present work. The p-Be-7 interaction potential used in the CDCC calculation is also used in the ANC analysis of Be-7(p,gamma)B-8. The value of S-17(0)=21.7(-0.55)(+0.62) eV b obtained is consistent with the previous one obtained from a precise measurement of the p-capture reaction cross section extrapolated to zero incident energy, S-17(0)=22.1 +/- 0.6 (expt) +/- 0.6 (theo) eV b, where (theo) stands for the error in the extrapolation. Thus, the agreement between the values of S-17(0) obtained from direct Be-7(p,gamma)B-8 and indirect B-8-breakup measurements is significantly improved.

DOI： 10.1103/PhysRevC.73.024605

Language：English   Publishing type：Research paper (scientific journal)  

We propose a fully quantum-mechanical method of treating four-body nuclear breakup processes in scattering of a projectile consisting of three constituents, by extending the continuum-discretized coupled-channels method. The three-body continuum states of the projectile are discretized by diagonalizing the internal Hamiltonian of the projectile with the Gaussian basis functions. For He-6+C-12 scattering at 18 and 229.8 MeV, the validity of the method is tested by convergence of the elastic and breakup cross sections with respect to increasing the number of the basis functions. Effects of the four-body breakup and the Borromean structure of He-6 on the elastic and total reaction cross sections are discussed.

DOI： 10.1103/PhysRevC.70.061601

Language：English   Publishing type：Research paper (scientific journal)  

Strength of the ∑ single-particle potential in nuclei from semiclassical distorted wave model analysis of the (π-, K +) inclusive spectrum
The semiclassical distorted wave model is developed to describe (π -, K+) inclusive spectra related to ∑- formation measured at KEK with pπ = 1.2 GeV/c. The shape and magnitude of the spectrum obtained with a 28Si target are satisfactorily reproduced using a repulsive ∑-nucleus potential whose strength is of the order of 30-50 MeV. This strength is not as large as the value of more than 100 MeV obtained using the estimation presented in the report of the experiment.

DOI： 10.1143/PTP.112.895

Language：English   Publishing type：Research paper (scientific journal)  

We present an accurate method of simultaneously treating nuclear and Coulomb breakup of weakly bound nuclei by means of the method of continuum discretized coupled channels with the pseudostate method of discretization. As L-2-type basis functions of expansion of bound and continuum states of the projectile, we take complex-range Gaussian functions which in good approximation form a complete set in a large configuration space which is important for both nuclear- and Coulomb-breakup processes. The accuracy of the method is tested quantitatively for B-8+Ni-58 scattering at 25.8 MeV.

DOI： 10.1103/PhysRevC.70.047604

Language：English   Publishing type：Research paper (scientific journal)  

Analysis of B-8 dissociation with the Asymptotic Normalization Coefficient (ANC) method is proposed to determine the astrophysical factor S-17(0) accurately. An important advantage of the analysis is that uncertainties of the extracted S-17(0) coming from the use of the ANC method can quantitatively be evaluated, in contrast to previous analyses using the Virtual Photon Theory (VPT). Calculation of measured spectra in dissociation experiments is done by means of the method of Continuum-Discretized Coupled-Channels (CDCC). From the analysis of Ni-58(B-8,Be-7+p)Ni-58 at 25.8 MeV, S-17(0) = 22.3 +/- 0.64(theo) +/- 2.23(expt) (cVb) is obtained; the ANC method turned out to work in this case within 1% of error.

DOI： 10.1016/j.nuclphysa.2004.04.078

Language：English   Publishing type：Research paper (scientific journal)  

To study how halo structure affects on He-6 + C-12 elastic scattering at 38.3 MeV/nucleon, we propose the four-body continuum-discretized coupled-channels (CDCC) method. In this method, three-body wave functions of He-6, nucleus are obtained by Gaussian expansion method (GEM). in this analysis, He-6 halo effects are investigated by comparing He-6 + C-12 scattering with Li-6 + C-12 scattering.

DOI： 10.1016/j.nuclphysa.2004.04.089

Language：English   Publishing type：Research paper (scientific journal)  

We propose a new method for treating both nuclear and Coulomb breakup processes with high accuracy and computational speed. The scattering amplitude of breakup reaction is decomposed into the lower and higher partial-wave parts. The former is calculated with the continuum-discretized coupled-channels method (CDCC) and the latter with a new version of CDCC in which the trajectory of projectile is assumed to be a straight line. Validity of this hybrid calculation is tested for Ni-58(B-8, Be-7+p)Ni-58 at 240 MeV. The hybrid calculation is opening the door to the systematic analysis of B-8 dissociation measured at RIKEN, MSU, and GSI, to determine the astrophysical factor S-17(0) accurately.

DOI： 10.1103/PhysRevC.68.064609

Language：English   Publishing type：Research paper (scientific journal)  

A new method of pseudostate discretization is proposed for the method of continuum discretized coupled channels to deal with three-body breakup processes. In the method, discrete S-matrix elements to the pseudo (discretized) continuum states are transformed into smooth ones to the exact continuum states of the projectile. As for the basis functions for describing pseudostate wave functions, we take real- and complex-range Gaussian functions, which form in good approximation a complete set in a finite configuration space being important for breakup processes. This "approximate-completeness" property is essential to make transformed S-matrix elements accurate. Moreover, the use of these Gaussian bases is expected to be very useful to describe four-body breakup processes. Accuracy of the method is tested quantitatively for two realistic examples: elastic and projectile-breakup processes in d+Ni-58 scattering at 80 MeV and those in Li-6+Ca-40 at 156 MeV.

DOI： 10.1103/PhysRevC.68.064607

Language：Others  

Semiclassical Distorted Wave Model Analysis of Backward Proton Emission from $(p,p^{prime}x)$ Reactions at Intermediate Energies
A semiclassical distorted wave (SCDW) model with Wigner transform of one-body<br />
density matrix is presented for multistep direct $(p,p^{prime}x)$ reactions to<br />
the continuum. The model uses Wigner distribution functions obtained in methods<br />
which include nucleon-nucleon correlations to a different extent, as well as<br />
Woods-Saxon (WS) single-particle wave function. The higher momentum components<br />
of target nucleons that play a crucial role in reproducing the high-energy part<br />
of the backward proton spectra are properly taken into account. This SCDW model<br />
is applied to analyses of multistep direct ...

Language：English  

DOI： 10.1103/PhysRevC.67.019902

Language：English   Publishing type：Research paper (scientific journal)  

The semiclassical distorted wave (SCDW) model of multistep direct processes is extended to calculate the double differential inclusive cross section (DDX) and the complete set of spin transfer coefficients (D-ij) at energies of 350-400 MeV taking account of one- and two-step processes. The DDX for (p, p'x) on Ca-40 at 392 MeV is calculated and compared with experimental data. The calculated D-ij and the DDXs for (p, nx) on C-12 and Ca-40 at 346 MeV for the emission angle of 22 are compared with the measured ones. Features of the calculated D-ij, the contribution of two-step processes in particular, are discussed in terms of the comparison with those of the DDX. The calculated DDX and D-ij are analyzed in terms of the choice of the bare NN force on which the effective interaction is based, the difference in the methods of the calculation of G matrices, and the in-medium modification of effective interactions. (C) 2001 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0375-9474(01)01339-2

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Event date： 2022.10

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Venue：学士会館   Country：Japan  

Event date： 2022.9

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Venue：大阪大学核物理研究センター   Country：Japan  

Event date： 2022.7

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Venue：JA長野県ビル   Country：Japan  

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Venue：Zoom   Country：Japan  

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Some note on the correspondence between nuclear clustering and scattering observables

Event date： 2020.8

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Event date： 2019.12

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Event date： 2019.10

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Description of (p,pN), (p,pa), and (p,pd) reactions

Event date： 2019.10

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Event date： 2019.9

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Event date： 2019.9

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Event date： 2019.8

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Direct reaction studies for revealing static and dynamical properties of nuclear systems I

Event date： 2019.8

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Direct reaction studies for revealing static and dynamical properties of nuclear systems II

Event date： 2019.8

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Event date： 2019.8

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Event date： 2019.3

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Some recent attempts for probing several faces of nuclei

Event date： 2019.3

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Some nuclear astrophysical studies with CDCC

Event date： 2019.3

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Event date： 2019.3

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Event date： 2019.3

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Event date： 2019.2

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Cross sections and spin polarization observables in exclusive and inclusive knockout reactions

Event date： 2019.2

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Event date： 2018.12

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Microscopic reaction theory to probe several faces of nuclei

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Some nuclear astrophysical studies with the Continuum-Discretized Coupled-Channels method (CDCC)

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Event date： 2017.12

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Direct reaction studies on exotic nuclear systems

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Applicability of CDCC to the deuteron breakup at low energies

Event date： 2017.1

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Event date： 2016.12

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Probing nuclear many-body correlations via knockout reactions

Event date： 2016.12

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Direct Reaction Studies on Nuclear Clustering

Event date： 2016.11

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Event date： 2016.10

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Microscopic effective reaction theory for three- and four-body direct processes

Event date： 2016.10

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Event date： 2016.9

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28pTA-9 Target mass number dependence of one-neutron removal cross section due to the nuclear interaction

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30aTB-5 Breakup effects of projectile and residual nucleus on transfer reaction

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Non-resonant Triple-α Reaction Rate at Low Temperature

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Investigation of the unbound 21C nucleus via transfer reaction

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Role of nuclear and Coulomb interactions in breakup of halo nuclei

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Application of the cPVC method to the inelastic scattering(II).

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Study of tensor-force effect via ^<16>O(p,d) reaction

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重陽子入射反応用断面積計算コードシステムの開発

DOI： 10.11561/aesj.2013s.0.50.0

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26aHA-6 Study of tensor correlations in ^4He via the ^4He(p,dp) reaction

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26aHE-1 Decay mode of the 2^+ resonance of ^6He

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27aHB-2 The finite range effect on the subbarrier α transfer reaction

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27pHE-2 Application of the continuum PVC method to the inelastic scattering

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29aHE-1 Forefront of microscopic reaction theories

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13pSB-6 Nuclear Reaction and Nucleosynthesis

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11aSA-6 Scattering cross section using the continuum particle-vibration coupling in coordinate space representation

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11aSC-6 Determination of ^8B(p,γ)^9C reaction rate from ^9C breakup

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19pSF-5 Determination of ^8B(p,γ)^9C Reaction Rate from ^9C Breakup

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18aSL-12 The CDCC analysis of ^6He+^<12>C, ^<208>Pb reactions

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19aSF-2 Deformation effect on neutron-rich Neon isotopes induced reaction cross section

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28pGH-3 Analysis of incomplete and complete fusions in deuteron induced reaction with eikonal reaction theory

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25aGJ-11 A new reaction theory on scattering of unstable nuclei

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25aGJ-12 Application of the eikonal reaction theory to ^<31>Ne induced reactions

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12pSE-8 New understanding of the formation of ^<12>C II

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12aSB-2 Deformation effects on reactions of unstable nuclei

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12pSE-10 Determination of the reaction rate for ^<13>C(α,n)^<16>O by means of CDCC analysis of sub barrier α transfer reaction

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12pSE-2 Investigation on surrogate reactions with CDCC

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12pSE-3 Systematic analysis of reaction cross section for deuteron induced reaction with Continuurn-Discretized Coupled-Channels method

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22p6D-6 Breakup reaction of the Borromean nucleus ^<14>Be

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20aBH-2 Localized microscopic optical potential for nucleon-nucleus scattering

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20aBH-3 Analysis of deuteron induced incomplete fusion reactions on heavy targets with Continuum-Discretized Coupled-Channels method

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20pBC-9 New understanding of the formation of ^<12>C

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30pZC-5 Accurate description of ternary processes for the astrophysical 3α reaction

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27aXF-3 Nuclear reaction studies with SAMURAI 7

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28aXF-7 Analysis of deuteron induced incomplete fusion reaction with Continuum-Discretized Coupled-Channels method

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29pZC-6 Study of single particle state of neutron-rich nuclei through the (p,2p) reactions

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23pSB-5 Accurate description of ternary processes for the astrophysical 3α reaction

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23aSA-3 Theoretical approach to analysis of spin observables for (p,2p) reactions

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23aSA-6 Microscopic scattering theory on nucleus-nucleus reactions in the intermediate and high energy regions

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23aSA-7 Analysis of deuteron induced incomplete fusion reaction with Continuum-Discretized Coupled-Channels method

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21aSB-6 Study on proton/neutron distribution of unstable nuclei with deuterium target

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23pZV-11 New smoothing method for the strength distribution of electric transition for ^6He

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23pZV-10 Contributions of half-off-shell g matrix elements to ^<12>C(p, 2p) cross-sections

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22aZD-8 Dependence of nuclear/Coulomb breakup ratio on target nuclei 2

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21aZD-9 Analysis of (K^-,K^+) Reaction on heavy targets with Semiclassical Distorted Wave Model

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22aZD-13 Smoothing Procedure of ^6He Breakup Cross Section Based on CDCC

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28pSB-6 DWIA calculation of the ^<12>C(p,2p) reaction with the local semi-classical approximation

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27aSC-7 Dependence of nuclear/Coulomb breakup ratio on target nuclei

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27aSC-9 Calculation of various cross sections for breakup reactions of neutron rich nuclei

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27pSC-11 Contributions of Multi-step Processes in (K^-,K^+) Reaction Analyzed by Semiclassical Distorted Wave Model

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28pSB-5 CDCC analysis of four-body breakup reaction of ^6He

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23aSD-9 Contributions of Multi-step Processes in (K^-,K^+) Reaction Analyzed by Semiclassical Distorted Wave Model

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20aSC-7 CDCC analysis of proton-^8B elastic scattering

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20aSC-9 Description of (^6He, ^4He n n) breakup reaction with continuum discretized coupled channels method

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23aSC-2 Microscopic calculation of proton-stable nucleus elastic scattering cross section

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23aSC-4 Solution to the longstanding analyzing power problem for inclusive quasielastic (p,p') Scattering

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30pWB-10 Analysis of (K^-, K^+) Ξ Production Reaction at Threshold Region with Semiclassical Distorted Wave Model

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28pWP-5 Analysis of nuclear and Coulomb breakup with three-body and four-body CDCC

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29pWF-4 Scattering of composite particle with nonlocal nucleon-optical potentials (I)

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29pWF-5 Four-body CDCC analysis of ^6He+^<209>Bi scattering near Coulomb barrier energies

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27pWD-7 Role of nuclear interactions in breakup processes of unstable nuclei at intermediate energies

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24aWH-7 SCDW analyses of (π, K) inclusive spectra using Wigner transformation of a Green's function

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24aWH-8 Analysis of (K^-,K^+) Ξ Production Reaction with Semiclassical Distorted Wave Model

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27pWD-10 E1 effects for Coulomb breakup of ^6He

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27pWD-11 The CDCC analysis of Coulomb and nuclear breakup of ^<11>Be

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29aSG-9 Pseudo-state CDCC analysis of Coulomb breakup

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27aSJ-2 Validity of the ANC method for ^8B breakup reactions

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29aSG-4 Eikonal CDCC analysis of breakup of unstable nuclei at intermediate energies

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29aSG-5 Energy dependence of ^6He breakup effect for ^6He+^<12>C elastic scattering

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28pZL-14 The validity of the ANC method in the unstable nuclear reaction

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27pZH-16 Determination of S_<17> from ^7Be(d, n)^8B at 24 MeV

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27pZL-10 Σ mean field from SCDW analyses of KEK (π^-, K^+) inclusive spectra on nuclei

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28aZL-1 CDCC analysis of four-body breakup effect on elastic ^6He+^<12>C scattering III

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28aZL-6 Effects of nuclear interactions and multistep processes on ^8B breakup reactions at intermediate energies

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28aZL-9 ^<11>Li+^<12>C scattering with the four-body CDCC method

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CDCC analysis of four body breakup effect on elastic ^6He+^<12>C scattering II

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Determination of S_<17> based on CDCC analyses for ^8B breakup reactions at intermediate energies

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The Eikonal CDCC (E-CDCC) analysis of breakup reactions

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Application of semiclassical DWIA method to the description of (π, K^+) inclusive spectra

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Determination of S_<17> based on CDCC analyses for 8^B Coulomb breakup reactions II

Language：Japanese  

CDCC analysis of three-body breakup effect on elastic ^6He+^<12>C scattering

Language：Japanese  

The pseddostate-CDCC method for breakup reactions indnced by three-cluster nucleus

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Determination of S_<17> based on CDCC analyses for ^8B Coulomb breakup reactions

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Depelldellce of the compiete set of spin transfer coeffeients in mid-dle angulr region on effective interactions in nuclear medium

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Spin transfer coetTmients in one-step calculation of (p,p'x) inclusive reactions with microscopic scattering wave functions by the DDHF field

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Calculation of the complete set of spin transfer coefficjents including up to two-step process in proton incident reactions at 346 MeV

Language：Japanese  

Nuclear matter calculations with the exact treatment of the Pauli operator

Language：Japanese  

Application of the semiclassical distorted wave model with Wigner transform to nucleon-induced multistep reactions

Language：Japanese  

Contribution of the two-step process in the proton incident reactions at 350-400 MeV with the Semi-Classical Distorted Wave (SCDW) model

Language：Japanese  

26aSK-8 Analysis of the proton incident reactions at 350-400 MeV with the Semi-Classical Distorted Wave(SCDW)model

Language：Japanese  

29p-YF-2 Calculation of spin observables with Semi-Classical Distorted Wave model(SCDW) : the analyses for the contribution of multi-step process and the in-medium effects

Language：Japanese  

Calculation of spin observables with Semi-Classical Distorted Wave model(SCDW)

Language：English  

3a-C-1 Analysis of (p,p'x) reactions by semi-classical distorted-wave (SCDW) model with single particle wave functions for Woods-Saxon potential

Language：Japanese  

Semi-classical distoried wave model with Wigner transform for nucleon-induced multi-step direct reaction

Language：Japanese  

Effects of exchange term and off-shell matrix element in Semi-Classical Distorted Wave(SCDW)approximation for nucleon inelastic and charge exchange scattering