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

DOI： 10.1103/physrevc.108.034305

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

Japanese Evaluated Nuclear Data Library version 5: JENDL-5

DOI： 10.1080/00223131.2022.2141903

Language：English   Publisher：EDP Sciences  

Japanese Evaluated Nuclear Data Library version 5 (JENDL-5) was released in 2021. JENDL-5 is intended to extend its generality from JENDL-4.0 by covering a wide variety of nuclear data for applications not only to nuclear design and decommissioning, but also to radiation-related fields. Overview of JENDL-5 and a future plan for the next of JENDL-5 are presented. JENDL-5 includes up-to-date neutron reaction cross sections incorporating other various types of data such as newly evaluated nuclear decay, fission yield, and thermal neutron scattering law. The neutron induced reaction cross sections especially on minor actinides in the resonance regions are improved by the experimental data measured at ANNRI. The extensive benchmark analyses on neutron nuclear data were made and the performance of JENDL-5 was confirmed by benchmark tests of ICSBEP and IRPhEP as well as fast reactors, radiation shielding calculations, and so on. So far, several JENDL special-purpose files have been developed for various applications. The data cover neutron, charged particles, and photon induced reactions. As the neutron induced reaction files, two special purpose files of JENDL/AD-2017 and JENDL/ImPACT-2018 were released to meet needs of nuclear backend applications including activation evaluation for nuclear facilities and nuclear transmutations of high-level radioactive wastes of long-lived fission products, respectively. Furthermore, the photon, proton and deuteron data were released as JENDL/PD-2016.1, JENDL-4.0/HE and JENDL/DEU-2020, respectively, for accelerator applications. With updating the data, they were incorporated in JENDL-5 as sub-libraries for facilitation of usability of JENDL. As the next step of JENDL-5, we are planning to provide the proper and sufficient covariance data that will contribute to uncertainty estimation in various applications.

DOI： 10.1051/epjconf/202328414001

researchmap

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

DOI： 10.1080/00223131.2022.2061622

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

Recently, great interest has arisen concerning Lu-177 as one of the most important therapeutic radionuclides for treating neuroendocrine tumors. This has driven demand for Lu-177 with high radionuclide purity produced in accelerators, by using highly enriched Yb-176 samples to develop a variety of mix-labelled radiopharmaceuticals. In this paper, a method is presented to estimate isotopic compositions of enriched Yb-176 samples required for achieving large-scale production of Lu-177 having high radionuclide purity by the Yb-176(d,x)Lu-177 reaction. These isotopic compositions were estimated using the latest measured excitation functions of the Yb-nat(d,x)Lu reaction that were confirmed in this study by measuring the integral yields of the reaction, and a particle transport simulation code. The estimated radionuclide purity of Lu-177 for commercially available enriched Yb-176 sample is over 99% at a deuteron energy of 20MeV. The method plays an important role in determining isotopic compositions of enriched samples for producing high purity medical radionuclides in accelerators.

DOI： 10.7566/JPSJ.91.044201

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

DOI： 10.1016/j.nds.2021.04.006

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

DOI： 10.1103/physrevc.103.024309

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

DOI： 10.1080/00223131.2020.1813643

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

Background: The isotope Mo-99, the generator of Tc-99m used for diagnostic imaging, is supplied by extraction from fission fragments of highly enriched uranium in reactors. However, a reactor-free production method of Mo-99 is sought worldwide due to concerns about nuclear proliferation.Purpose: Production methods using accelerators have attracted attention. Recently, Mo-99 production through a muon capture reaction was proposed and it was found that about 50% of Mo-100 turned into Mo-99 through the Mo-100 (mu-, n) reaction [I. Hashim et al., Nucl. Instrum. Methods Phys. Res., Sect. A 963, 163749 (2020)]. However, the detailed physical process of the muon capture reaction is not completely understood. We therefore study the muon capture reaction on Mo-100 by a theoretical approach.Methods: We use the proton-neutron quasiparticle random phase approximation to calculate the muon capture rate. The muon wave function is calculated with consideration of the electronic distribution of the atom and the nuclear charge distribution. The particle evaporation process from the daughter nucleus, Nb-100, is calculated by the Hauser-Feshbach statistical model.Results: From the model calculation, about 38% of Mo-100 is converted to Mo-99 through the muon capture reaction, which is in reasonable agreement with the experimental data. It is revealed that negative parity states, especially the 1(-) state, play an important role in Mo-100 (mu(-), n)Nb-99. Charged particle emission is hindered due to its large separation energy and the Coulomb barrier.Conclusions: Isotope production by the muon capture reaction strongly depends on the nuclear structure. To understand the mechanism, excitation energy functions have to be known microscopically.

DOI： 10.1103/physrevc.102.034306

Language：English  

Status of JENDL
Recent progress and future plan of the JENDL project are presented. Two special purpose files were released recently. One is the JENDL Photonuclear Data File 2016 (JENDL/PD-2016) and the other one is the JENDL Activation Cross Section File for Nuclear Decommissioning 2017 (JENDL/AD-2017). Regarding the general-purpose file, we are planning to release a next version of JENDL-4.0 opened in 2010, which would be made available by 2022 as JENDL-5. New data evaluation and revision are in progress. The first test version of the JENDL-5 called JENDL-5$alpha$1 has been created by updating neutron reaction data for about 100 nuclides.

DOI： 10.1051/epjconf/202023909002

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

We measured the yields of radionuclides after neutron irradiation on an enriched (ZnO)-Zn-68 sample covered with polyethylene blocks. The neutrons were generated from the Be-9(d,n) reaction by 40 and 50 MeV deuterons. For 50 MeV deuterons we observed anomalously enhanced yields of Ga-67, Ga-66, Zn-69(m), and Cu-64, more than 20-times larger than the yields for a (ZnO)-Zn-68 sample without the polyethylene blocks. At the same time, the yields of the same radioisotopes produced from an enriched metallic Zn-68 sample were almost insensitive to the presence of polyethylene. On the other hand, for 40 MeV deuterons the enhanced production was not observed. This finding would provide a unique capability of accelerator neutrons to simultaneously produce large amounts of several radioisotopes via neutron-induced reactions on a single sample. The experimental data are compared with the yields calculated by the simulation code Particle and Heavy Ion Transport code System (PHITS). The calculated yields of these radioisotopes produced from the (ZnO)-Zn-68 sample covered with the polyethylene blocks considerably disagree with the measured ones, while for the (ZnO)-Zn-68 sample without the blocks they agree with each other.

DOI： 10.7566/JPSJ.89.034201

Language：English  

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

A new nuclear data library, JENDL/ImPACT-2018, was developed for an innovative study on the transmutation of long-lived fission products. Nuclear reaction cross-sections were newly evaluated for incident neutrons and protons up to 200 MeV for 163 nuclides focusing on long-lived nuclei such as Se-79, Zr-93, Pd-107 and Cs-135, adopting some parts of JENDL-4.0. Our challenge was an evaluation of cross-sections for a number of unstable nuclei over a wide energy range where the experimental data were very scarce. We estimated cross-sections based on a nuclear model code CCONE by incorporating an advanced knowledge on the nuclear structure theory and a model-parameterization based on new experimental cross-sections measured by the inverse kinematics. Through comparisons with available experimental data on the stable isotopes, it is found that the present data give better agreements with them than those in the existing libraries. In a neutronics simulation by the PHITS code, we also found that the largest impact of the present library was seen on the estimated amount of isotope productions.

DOI： 10.1080/00223131.2019.1647889

Language：English  

Statistical properties of thermal neutron capture cross sections calculated with randomly generated resonance parameters
We investigated the probability distribution of thermal neutron capture cross sections ($sigma_{
m th}$) deduced stochastically with the resonance parameters randomly sampled from Wigner and Porter-Thomas distributions. We found that the typical probability distribution has an asymmetric shape. While there is a long tail on the large $sigma_{
m th}$ side due to a resonance happening to be close to the thermal energy, the multiresonance contribution considerably reduces the probability on the small $sigma_{
m th}$ side. We also found that the probability distributions have a similar shape if nuclei have an average resonance spacing sufficiently larger than an average radiation width. We compared the typical probability distribution with the distribution of the experimental values of 193 nuclei and found a good agreement between them.

DOI： 10.1103/PhysRevC.100.014610

Language：English  

Phenomenological level density model with hybrid parameterization of deformed and spherical state densities
A phenomenological level density model that has different level density parameter sets for the state densities of the spherical and the deformed states, and the optimization of the parameters using the experimental data of the average s-wave neutron resonance spacing are presented. The transition to the spherical state from the deformed one is described using the parameters derived from a microscopic nuclear structure calculation. The nuclear reaction calculation has been performed by the statistical model using the present level density. Resulting cross sections for various reactions with the spherical, deformed and transitional target nuclei shows a fair agreement with the experimental data, which indicates the effectiveness of the present model. The role of the rotational collective enhancement in the calculations of those cross sections is also discussed.

DOI： 10.1080/00223131.2019.1588801

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

A neutron source from the C(d,n) reaction has the unique capability of producing medical radioisotopes such as Mo-99 with a minimum level of radioactive waste. Precise data on the neutron flux are crucial to determine the best conditions for obtaining the maximum yield of Mo-99. The measured yield of Mo-99 produced by the 100Mo(n,2n)Mo-99 reaction from a large sample mass of MoO3 agrees well with the numerical result estimated with the latest neutron data, which are a factor of two larger than the other existing data. This result establishes an important finding for the domestic production of Mo-99: approximately 50% of the demand for Mo-99 in Japan could be met using a 100 g (MoO3)-Mo-100 sample mass with a single accelerator of 40 MeV, 2mA deuteron beams.

DOI： 10.7566/JPSJ.87.043201

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

Incident neutron energy dependence of delayed neutron yields of uranium and
plutonium isotopes is investigated. A summation calculation of decay and
fission yield data is employed, and the energy dependence of the latter part is
considered in a phenomenological way. Our calculation systematically reproduces
the energy dependence of delayed neutron yields by introducing an energy
dependence of the most probable charge and the odd-even effect. The calculated
fission yields are assessed by comparison with JENDL/FPY-2011, delayed neutron
activities, and decay heats. Although the fission yields in this work are
optimized to delayed neutron yields, the calculated decay heats are in good
agreement with the experimental data. Comparison of the fission yields
calculated in this work and JENDL/FPY-2011 gave an important insight for the
evaluation of the next JENDL nuclear data.

DOI： 10.1080/00223131.2018.1470947

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

DOI： 10.1103/physrevc.97.029901

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

For $N=Z$ odd-odd nuclei, a three-body model assuming two valence particles
and an inert core can provide an understanding of pairing correlations in the
ground state and spin-isospin excitations. However, since residual core-nucleon
interactions can have a significant impact on these quantities, the inclusion
of core excitations in the model is essential for useful calculation to be
performed. The effect of core excitations must be included in order to gain a
detailed understanding of both the ground state and spin-isospin properties of
these systems. To this end, we include the vibrational excitation of the core
nucleus in our model. We solve the three-body core-nucleon-nucleon problem
including core vibrational states to obtain the nuclear ground state as well as
spin-isospin excitations. The spin-isospin excitations are examined from the
point of view of SU(4) multiplets. By including the effect of core excitation,
several experimental quantities of $N=Z$ odd-odd nuclei are better described,
and the root mean square distances between proton and neutron and that between
the center of mass of proton and neutron and core nucleus increase. Large
$B$($M1$) and $B$(GT) observed for $^{18}$F and $^{40}$Ca were explained in
terms of the SU(4) symmetry. The core nucleus is meaningfully broken by the
residual core-nucleon interactions, and various quantities concerning
spin-isospin excitations as well as the ground state become consistent with
experimental data. Including the core excitation in the three-body model is
thus important for a more detailed understanding of nuclear structure.

DOI： 10.1140/epja/s10050-020-00035-w

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

We, for the first time, measured the yield of Mo-99, the mother nuclide of Tc-99m used in nuclear medicine diagnostic procedures, produced by the Mo-100(n,2n)Mo-99 reaction with accelerator neutrons. The neutrons with a continuous energy spectrum from the thermal energy up to about 40 MeV were provided by the C(d,n) reaction with 40 MeV deuteron beams. It was proved that the Mo-99 yield agrees with that estimated by using the latest data on neutrons from the C(d,n) reaction and the evaluated cross section of the Mo-100(n,2n)Mo-99 reaction given in the Japanese Evaluated Nuclear Data Library. On the basis of the agreement, a systematic calculation was carried out to search for an optimum condition that enables us to produce as much Mo-99 as possible with a good Mo-99/Mo-100 value from an economical point of view. The calculated Mo-99 yield from a 150 g (MoO3)-Mo-100 sample indicated that about 30% of the demand for Mo-99 in Japan can be met with a single accelerator capable of 40 MeV, 2 mA deuteron beams. Here, by referring to an existing F-18-fluorodeoxyglucose (FDG) distribution system we assumed that Tc-99m radiopharmaceuticals formed after separating Tc-99m from Mo-99 can be delivered to hospitals from a radiopharmaceutical company within 6 h. The elution of Tc-99m from Mo-99 twice a day would meet about 50% of the demand for Mo-99.

DOI： 10.7566/JPSJ.86.114803

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

The low-lying dipole strength in Cr-52 was measured in nuclear resonance fluorescence experiments using a quasimonochromatic, linearly polarized photon beam. The parities of the excited dipole states were determined by the intensity asymmetry of resonantly scattered gamma rays with respect to the polarization plane of the incident photon beam. We observed 62 resonances at excitation energies between 7.5 and 12.1 MeV. The observed M1 and E1 strengths were compared via random-phase-approximation calculations using the Skyrme interaction. The effects of two-particle-two-hole configuration mixing and tensor force on dipole strength distributions were investigated.

DOI： 10.1103/PhysRevC.96.044316

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

Status of the JENDL project after releasing the latest general purpose file JENDL-4.0 is described. By correcting errors and adding covariance data of JENDL-4.0, 38 files have been released as JENDL-4.0u. Development of next general purpose file JENDL-5 is also in progress. New evaluations have been performed for light nuclei, structural materials and fission products. Two special purpose files, JENDL-4.0/HE and JENDL/DDF-2015 were released in 2015. The former includes neutron induced reaction data for 130 nuclides in the energy region up to 200 MeV as well as proton induced reaction data for 133 nuclides. The latter is the decay data file of 3,237 nuclides from Z = 1 to 104 and neutron. Other two special purpose files of activation cross section and photonuclear data are under preparation and will be released soon.

DOI： 10.1051/epjconf/201714602005

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

Coherent one-particle one-hole (1p1h) excitations have given us effective
insights into general nuclear excitations. However, the two-particle two-hole
(2p2h) excitation beyond 1p1h is now recognized as critical for the proper
description of experimental data of various nuclear responses. The spin-flip
charge-exchange reactions $^{48}{
m Ca}(p,n)^{48}{
m Sc}$ are investigated to
clarify the role of the 2p2h effect on their cross sections. The Fermi
transition of $^{48}{
m Ca}$ via the $(p,n)$ reaction is also investigated in
order to demonstrate our framework. The transition density is calculated
microscopically with the second Tamm-Dancoff approximation, and the
distorted-wave Born approximation is employed to describe the reaction process.
A phenomenological one-range Gaussian interaction is used to prepare the form
factor. For the Fermi transition, our approach describes the experimental
behavior of the cross section better than the Lane model, which is the
conventional method. For spin-flip excitations including the GT transition, the
2p2h effect decreases the magnitude of the cross section and does not change
the shape of the angular distribution. The $Delta l=2$ transition of the
present reaction is found to play a negligible role. The 2p2h effect will not
change the angular-distributed cross section of spin-flip responses. This is
because the transition density of the Gamow-Teller response, the leading
contribution to the cross section, is not significantly varied by the 2p2h
effect.

DOI： 10.1103/PhysRevC.96.054608

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

Interference effect of neutron capture cross section between the compound and
direct processes is investigated. The compound process is calculated by
resonance parameters and the direct process by the potential mode. The
interference effect is tested for neutron-rich $^{82}$Ge and $^{134}$Sn nuclei
relevant to $r$-process and light nucleus $^{13}$C which is neutron poison in
the $s$-process and produces long-lived radioactive nucleus $^{14}$C
($T_{1/2}=5700$ y). The interference effects in those nuclei are significant
around resonances, and low energy region if $s$-wave neutron direct capture is
possible. Maxwellian averaged cross sections at $kT=30$ and $300$ keV are also
calculated, and the interference effect changes the Maxwellian averaged capture
cross section largely depending on resonance position.

DOI： 10.1051/epjconf/201716300037

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

We study the proton-neutron RPA with an extended Lipikin-Meshkov-Glick model.
We pay attention to the effect of correlated ground state and the case in which
neutron and proton numbers are different. The effect of the correlated ground
state are tested on the basis of quasi-boson approximation. We obtain the
result that RPA excitation energies and transition strengths are in a good
agreement with the exact solution up to a certain strength of the
particle-particle interaction. However, the transition strength becomes worse
if we consider the case in which neutron and proton numbers are different even
at a weak particle-particle interaction.

DOI： 10.5506/APhysPolBSupp.10.131

Language：English  

Overview of JENDL-4.0/HE and benchmark calculations

DOI： 10.11484/jaea-conf-2016-004

Language：English  

DOI： 10.1103/PhysRevLett.116.089902

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

The dipole excitations of nuclei play an important role in nuclear astrophysics processes in connection with the photoabsorption and the radiative neutron capture that take place in stellar environment. We present here the results of a large-scale axially-symmetric deformed QRPA calculation of the γ-ray strength function based on the finite-range Gogny force. The newly determined γ-ray strength is compared with experimental photoabsorption data for spherical as well as deformed nuclei. Predictions of γ-ray strength functions and Maxwellian-averaged neutron capture rates for Sn isotopes are also discussed.

DOI： 10.1088/1742-6596/665/1/012058

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

A computer code system, CCONE, was developed for nuclear data evaluation within the JENDL project. The CCONE code system integrates various nuclear reaction models needed to describe nucleon, light charged nuclei up to alpha-particle and photon induced reactions. The code is written in the C++ programming language using an object-oriented technology.At first, it was applied to neutron-induced reaction data on actinides, which were compiled into JENDL Actinide File 2008 and JENDL-4.0. It has been extensively used in various nuclear data evaluations for both actinide and non-actinide nuclei. The CCONE code has been upgraded to nuclear data evaluation at higher incident energies for neutron-, proton-, and photon-induced reactions. It was also used for estimating β-delayed neutron emission.This paper describes the CCONE code system indicating the concept and design of coding and inputs. Details of the formulation for modelings of the direct, pre-equilibrium and compound reactions are presented. Applications to the nuclear data evaluations such as neutron-induced reactions on actinides and medium-heavy nuclei, high-energy nucleon-induced reactions, photonuclear reaction and β-delayed neutron emission are mentioned.

DOI： 10.1016/j.nds.2015.12.004

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

Two-particle two-hole (2p2h) effect on the Gamow-Teller (GT) transition for
neutron-rich nuclei is studied by the second Tamm-Dancoff approximation (STDA)
with the Skyrme interaction. Unstable $^{24}$O and $^{34}$Si, and stable
$^{48}$Ca nuclei are chosen to study the quenching and fragmentation of the GT
strengths. Correlation of the 2p2h configurations causes $20$% quenching and
downward shift of GT giant resonances (GTGRs). The residual interaction
changing relative angular momentum, appeared in the tensor force part, gives a
meaningful effect to the GT strength distributions. In this work, $17$ to $26$
% of the total GT strengths are brought to high energy region above GTGRs. In
particular, the tensor force brings strengths to high energy more than $50$
MeV. STDA calculation within a small model space for 2p2h configuration is also
performed and experimental data of $^{48}$Ca is reproduced reasonably.

DOI： 10.1103/PhysRevC.93.044319

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

An analysis of β-delayed neutron emission of even-even neutron-rich nuclei with proton-neutron QRPA
β-delayed neutron emission probabilities of even-even nuclei are examined with a proton-neutron quasi-particle random-phase-approximation (pnQRPA). To calculate a light particle evaporation from excited states of daughter nucleus populated by β-decay, the Hauser-Feshbach statistical model is used. We discuss effects of isospin T = 0 pairing, tensor force and nuclear deformation on the β-delayed neutron emission probability. We find that the effect of nuclear deformation is essential rather than the that of isospin T = 0 pairing and tensor force to give an appropriate β-feedings to energy window of neutron emission. The obtained β-delayed neutron emission probabilities are in reasonable agreement with the experimental data of several typical delayed neutron emitters. The results are also compared with the FRDM + QRPA calculation. We conclude that the present approach is promising to calculate β-delayed neutron.

DOI： 10.1016/j.pnucene.2014.07.021

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

We have for the first time studied the radionuclide purity of the therapeutic isotope Cu-67 produced by the Zn-68(n, x)(67)Cu reaction. The neutrons were obtained by the C-nat(d, n) reaction using 40 MeV deuterons. We measured the gamma-ray spectra of the reaction products produced by bombarding an enriched (ZnO)-Zn-68 sample with the neutrons with a high-purity Ge detector. We found that the relative production yields of the impurity radionuclides Cu-64, Zn-65, and Zn-69m to Cu-67 are extremely low. The result indicates that the Zn-68(n, x)Cu-67 reaction is the most promising among those proposed routes until now for producing high-quality Cu-67, and could solve a longstanding problem of establishing an appropriate production method for Cu-67.

DOI： 10.7566/JPSJ.83.073201

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

We estimated statistical uncertainties of a nondestructive assay system using nuclear resonance fluorescence (NRF) for spent nuclear fuel including low concentrations of actinide nuclei with an intense, mono energetic photon beam. Background counts from radioactive materials inside the spent fuel were calculated with the ORIGEN2.2-UPJ burn-up computer code. Coherent scattering contribution associated with Rayleigh, nuclear Thomson, and Delbruck scattering was also considered. The energy of he coherent scattering overlaps with that L of NRF transitions to the ground state. Here, we propose to measure NRF transitions to the first excited state to avoid the coherent scattering contribution. Assuming that L the total NRF cross-sections are in the range of 3-100 eV b at excitation energies of 225, 3.5, and 5 MeV, statistical uncertainties of the NRF measurement were estimated. We concluded that it is possible to assay 1% actinide content in the spent fuel with 2.2-32% statistical precision during 40005 measurement time for the total integrated cross-section of 30 eV b at excitation energies of 3.5-5 MeV by using a photon beam with an intensity of 106 photons/s/eV. We also examined both the experimental and theoretical NRF cross-sections for actinide nuclei. The calculation based On the quasi-particle random phase approximation suggests the existence of strong magnetic dipole resonances at excitation energies ranging from 2 to 6 MeV with the scattering cross-sections of tens eV b around 5 MeV in U-238. (C) 2013 Published by Elsevier B.V.

DOI： 10.1016/j.nima.2013.11.069

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

Applying the sum rule approach, we investigate the energy of a soft dipole motion in Lambda hypernuclei, which results from a dipole oscillation of a Lambda hyperon against the core nucleus. To this end, we systematically study single-Lambda hypernuclei, from O-16 Lambda to Pb-208(Lambda), for which the ground-state wave function is obtained in the framework of Hartree-Fock method with several Skyrme-type Lambda N interactions. Our results indicate that the excitation energy of the soft dipole Lambda mode, E-sd Lambda, decreases as the mass number increases. We find that the excitation energy is well parametrized as E-sd Lambda = 26.6A(-1/3) + 11.2A(-2/3) MeV for the SkM* NN interaction and E-sd Lambda = 21.3A(-1/3) + 22.6A(-2/3) MeV for the SIII NN interaction as a function of mass number A.

DOI： 10.1103/PhysRevC.88.064303

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

We discuss low-lying collective excitations of Λ hypernuclei using the self-consistent mean-field approaches. We first discuss the deformation properties of Λ hypernuclei in the sd-shell region. Based on the relativistic mean-field (RMF) approach, we show that the oblate deformation for 28Si may disappear when a Λ particle is added to this nucleus. We then discuss the rotational excitations of MgΛ25 using the three-dimensional potential energy surface in the deformation plane obtained with the Skyrme-Hartree-Fock method. The deformation of MgΛ25 is predicted to be slightly reduced due to an addition of a Λ particle. We demonstrate that this leads to a reduction of electromagnetic transition probability, B(E2), in the ground state rotational band. We also present an application of random phase approximation (RPA) to hypernuclei, and show that a new dipole mode, which we call a soft dipole Λ mode, appears in hypernuclei, which can be interpreted as an oscillation of the Λ particle against the core nucleus. © 2012 Elsevier B.V.

DOI： 10.1016/j.nuclphysa.2012.12.077

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

For the next version of JENDL general purpose file, neutron nuclear data on Pr-141,Pr-143 are evaluated considering cross sections and spectra provided from experiments in the fast neutron energy region up to 20 MeV. Total and elastic cross sections are derived from optical model. Pre-equilibrium and direct-reaction processes are taken into account in addition to the compound process. The statistical model is applied to calculate the cross sections above the resolved resonance region. For unstable Pr-143 nuclide having less experimental data, we use the same parameters as Pr-141 for mass-dependent and -independent terms in the optical potential. The resolved resonance parameter remains unchanged from JENDL-4.0. The present evaluations give consistent results with experimental data, reflecting newly measured one. The evaluated data are compiled in ENDF-6 format for the next version of JENDL.

DOI： 10.1080/00223131.2013.810125

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

A new system proposed for the generation of radioisotopes with accelerator neutrons by deuterons (GRAND) is described by mainly discussing the production of Mo-99 used for nuclear medicine diagnosis. A prototype facility of this system consists of a cyclotron to produce intense accelerator neutrons from the natC(d,n) reaction with 40MeV 2mA deuteron beams, and a sublimation system to separate Tc-99m from an irradiated (MoO3)-Mo-100 sample. About 8.1 TBq/week of Mo-99 is produced by repeating irradiation on an enriched Mo-100 sample (251 g) with accelerator neutrons for two days three times. It meets about 10% of the Mo-99 demand in Japan. The characteristic feature of the system lies in its capability to reliably produce a wide variety of high-quality, carrier-free, carrier-added radioisotopes with a minimum level of radioactive waste without using uranium. The system is compact in size, and easy to operate; therefore it could be used worldwide to produce radioisotopes for medical, research, and industrial applications.

DOI： 10.7566/JPSJ.82.064201

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

The effect of the tensor force on β decay is studied in the framework of the proton-neutron random phase approximation with the Skyrme force. The investigation is performed for even-even semimagic and magic nuclei, Si34, Ni68,78, and Sn132. The tensor correlation induces strong impact on the low-lying Gamow-Teller state. In particular, it improves the β-decay half-lives. Q and ft values are also investigated and compared with experimental data. © 2013 American Physical Society.

DOI： 10.1103/PhysRevLett.110.122501

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

We have measured the activation cross sections producing Cu-64 and Cu-67, promising medical radioisotopes for molecular imaging and radioimmunotherapy, by bombarding a natural zinc sample with 14MeV neutrons. We estimated the production yields of Cu-64 and Cu-67 by fast neutrons from C-nat(d,n) with 40 MeV 5 mA deuterons. We used the present result together with the evaluated cross section of Zn isotopes. The calculated Cu-64 yield is 1.8 TBq (175 g Zn-64) for 12 h of irradiation; the yields of Cu-67 by Zn-67(n,p) Cu-67 and Zn-68(n,x)Cu-67 were 249 GBq (184 g Zn-67) and 287 GBq (186 g Zn-68) at the end of 2 days of irradiation, respectively. From the results, we proposed a new route to produce 67Cu with very little radionuclide impurity via the Zn-68(n,x) Cu-67 reaction, and showed the Zn-64(n,p)Cu-64 reaction to be a promising route to produce Cu-64. Both Cu-67 and Cu-64 are noted to be produced using fast neutrons.

DOI： 10.7566/JPSJ.82.034201

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

The gamma-radiation has been investigated for Ni-63 produced by cold neutron capture in an enriched Ni-62 sample. The 315 gamma-rays produced were placed in a Ni-63 level scheme, in which 272 placements are new. We determined the excitation energies with 0.2-0.8 keV error and the branching ratios of 62 bound levels in Ni-63, including 30 new levels. The Q-value of the Ni-62(n, gamma)Ni-63 reaction amounts to 6837.75 +/- 0.18 keV. A large-scale shell-model calculation was performed that included the four single-particle orbits of 0f(7/2), 1p(3/2), 0f(5/2), and 1p(1/2), assuming an inert Ca-40 core for negative-parity states, and those of 1p(3/2), 0f(5/2), 1p(1/2), and 0g(9/2), assuming a Ni-56 core for positive-parity states. The energies of the low-lying Ni-63 states were successfully reproduced. A mean-field statistical-model calculation was also performed by using a self-consistent interaction between the Hartree-Fock + Bardeen-Cooper-Schrieffer method and the statistical calculation. The calculation result is consistent with the experimental level density of Ni-63.

DOI： 10.1143/JPSJ.81.084201

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

Using the Hartree-Fock plus random phase approximation (HF + RPA), we study the impurity effect of Lambda hyperon on the collective vibrational excitations of double-Lambda hypernuclei. To this end, we employ Skyrme-type Lambda N and Lambda Lambda interactions for the HF calculations, and the residual interactions for the RPA are derived with the same interactions. We find that the inclusion of two Lambda hyperons in O-16 shifts the collective states toward higher energies. In particular, the energy of the giant monopole resonance of 18 O-18(Lambda Lambda), as well as that of Pb-210(Lambda Lambda), becomes higher. This implies that the effective incompressibility modulus increases owing to the impurity effect of Lambda particles, if the beta-stability condition is not imposed.

DOI： 10.1103/PhysRevC.85.024316

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

Nuclear level density (NLD) evaluated under the framework of the microscopic statistical method is examined. We calculate single-particle levels by the Skyrme-Hartree-Fock (SHF) + Bardeen-Cooper-Schrieffer (BCS) method, and the grand partition function is calculated with the same two-body interaction as used in the SHF+BCS method. The results are compared with preceding theoretical calculations using different residual interactions. Cumulative numbers and s-wave neutron resonance spacings are reproduced fairly well. The effect of a renormalization term neglected in conventional microscopic statistical methods is also investigated. In order to test a practical application, we calculate neutron capture cross section and compare it with experimental results.

DOI： 10.3327/jnst.48.984

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

Fission barrier of actinide nuclei including two Lambda hyperons is studied in the framework of the Skyrme-Hartree-Fock approach at zero temperature. We adopt the zero-range Skyrme-type interaction between Lambda-N and Lambda-Lambda. Fission barrier is investigated using several parameter sets for Lambda Lambda interactions. We obtain the result that the barrier height becomes higher as the number of Lambda particle increases and the barrier width has a dependence on the Lambda Lambda interaction. A relation between Lambda binding energy and density distribution of Lambda particle inside a core nucleus is also discussed. We found that the both Lambda particles are attracted into heavier fission fragment. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nuclphysa.2011.02.127

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

We estimated the production yield of Mo-99 from Mo-100(n, 2n)Mo-99 using neutrons produced by bombarding a natural carbon target, C-nat, with 40 MeV 5 mA deuterons. We used the latest data for the angular and energy distributions of neutrons from C-nat(d, n) and the evaluated cross section of Mo-100(n, 2n)Mo-99 given in the Japanese Evaluated Nuclear Data Library to estimate the Mo-99 yield. The Mo-99 yields were obtained for different distances d between the carbon target and the Mo-100 sample, and for different Mo-100 sample radii and thicknesses. We typically obtained a 7.1 TBq activity of Mo-99 at the end of neutron irradiation for two days for a Mo-100 sample (251 g) placed at d 2 cm. The obtained Mo-99 activities show that a substantial fraction of the current Mo-99 demand in Japan could be met by adopting the proposed production method.

DOI： 10.1143/JPSJ.79.093201

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

beta-decay half-lives around Ni-78 and Sn-132 are studied with proton-neutron Quasiparticle Random Phase Approximation on the basis of Skyrme-Hartree-Fock (SHF) method. We take into account tensor force correlation in calculating the ground and excited states and find it improves the half-life of Sn-132. However, the Q value is still underestimated. We also discuss that half-lives do not strongly depend on type of particle-particle interaction in isospin T = 0 channel.

DOI： 10.1142/S0217732310000903

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

Fission-related phenomena of heavy Lambda hypernuclei are discussed with the constraint Skyrme-Hartree-Fock + BCS (SHF + BCS) method, in which a similar Skyrme-type interaction is employed also for the interaction between a Lambda particle and a nucleon. Assuming that the Lambda particle adiabatically follows the fission motion, we discuss the fission barrier height of (239)(Lambda)U. We find that the fission barrier height increases slightly when the Lambda particle occupies the lowest level. In this case, the Lambda particle is always attached to the heavier fission fragment. This indicates that one may produce heavy neutron-rich Lambda hypernuclei through fission, whose weak decay is helpful for the nuclear transmutation of long-lived fission products. We also discuss cases where the Lambda particle occupies a higher single-particle level. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nuclphysa.2009.09.063

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

Using the finite-temperature quasiparticle random phase approximation (FTQRPA) on the basis of the finite-temperature Skyrme-Hartree-Fock + Bardeen-Cooper-Schrieffer (BCS) method, we study beta(-)-decay half-lives for even-even neutron magic nuclei with N=82 in a finite-temperature environment. We find that the beta(-)-decay half-life first decreases as the temperature increases for all the nuclei we study, although the thermal effect is found to be small at temperatures relevant to r-process nucleosynthesis. Our calculations indicate that the half-life begins to increase at high temperatures for open-shell nuclei. We discuss this behavior in connection to the pairing phase transition.

DOI： 10.1103/PhysRevC.80.065808

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

We discuss the sensitivity of fission barrier for heavy neutron-rich nuclei to fission paths in the two-dimensional neutron-proton quadrupole plane. To this end, we use the constrained Skyrme-Hartree-Fock + BCS method, and examine the difference of fission barriers obtained with three constraining operators, that is, the neutron, proton, and mass quadrupole operators. We investigate (220)U, (236)U, and (266)U, that is relevant to r-process nucleosynthesis. We find that the fission barrier heights are almost the same among the three constraining operators even for neutron-rich nuclei, indicating that the usual way to calculate fission barriers with the mass quadrupole operator is well justified. We also discuss the difference between proton and neutron deformation parameters along the fission paths.

DOI： 10.1103/PhysRevC.77.044308

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

We discuss effects of the electron plasma on the charged-current neutrino-nucleus reaction (nu(e),e(-)) in a core-collapse supernova environment. We first discuss the electron screening effect on the final state interaction between the outgoing electron and the daughter nucleus. To this end, we employ a schematic surface peaked transition density and solve the Dirac equation for the outgoing electron with the screened Coulomb potential obtained with the Thomas-Fermi approximation. In addition to the screening effect, we also discuss the Pauli blocking effect due to the environmental electrons on the spectrum of the outgoing electron. We find that both effects hinder the cross section of the charged-current reaction, especially at low incident energies.

DOI： 10.1103/PhysRevC.75.045802

Event date： 2023.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2023.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：米国ハワイ州   Country：Japan  

Event date： 2023.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東海村   Country：Japan  

Event date： 2023.7

Language：English   Presentation type：Oral presentation (general)  

Venue：九州大学   Country：Japan  

Event date： 2023.4 - 2023.5

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福井（ハイブリッド）   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2023.2

Language：English  

Country：Japan  

Theoretical studies of beta-decay half-lives

Event date： 2023.2

Language：Japanese  

Venue：東京   Country：Japan  

Uncertainties of capture reactions of neutron-rich nuclei under various imposed conditionsconditions

Event date： 2023.2

Language：Japanese  

Venue：和光   Country：Japan  

$eta$-decays and delayed neutrons of neutron-rich nuclei

Event date： 2022.12

Language：Japanese  

Venue：札幌   Country：Japan  

Particle emission following muon capture and soft errors of semiconductors

Event date： 2022.11

Language：Japanese  

Venue：福岡   Country：Japan  

Calculation of particle emission following muon capture within nuclear structure models

Event date： 2022.9

Language：Japanese  

Venue：岡山   Country：Japan  

Particle emission following muon capture

Event date： 2022.7

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Study on beta-decay half-lives within the Skyrme EDF+QRPA

Event date： 2022.7

Language：English  

Venue：Toyonaka (online)   Country：Japan  

元素合成過程の一つとして提案されている$r$-processは、原子核が連続的に中性子捕獲反応を繰り返して中性子過剰核になり、$\beta$崩壊を繰り返して重い原子核へ成長していくことを予言している。$r$-processの理解を助けるためには、中性子過剰核の中性子捕獲反応や、$\beta$崩壊、$\beta$遅発中性子の情報が必要となる。中性子過剰核の$\beta$崩壊は、これまで世界的に様々な理論モデルを用いて調べられてきたが、軽い核から重い核までの$\beta$崩壊半減期を系統的に理論予測した研究は数例に限定されている。本研究では、$r$-processの理解促進に資する新しい$\beta$崩壊データを提供するために、Skyrme EDF+QRPA法を用いて研究を行っている。本発表では、最新の成果について報告するとともに、研究過程で見えてきた原子核構造と数値計算法に関する課題について議論をする。

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Event date： 2022.5

Language：English   Presentation type：Oral presentation (general)  

Country：France  

Study of particle emissions following after $eta$-decays and muon captures
Nuclei can be at an excited state by beta-decays and muon captures. If the excitation energy is above particle threshold energies, the nuclei emit particles competing with the gamma deexcitation. The typical examples are neutron emissions after beta-decays and muon captures. In addition, it is known that proton and alpha particle emissions occur for a highly excited neutron-deficient nuclei. The information is important not only for estimating delayed neutrons that play an important role for a stable operation of reactors, but also for evaluating radioactivities, soft errors of semi-conductors, and nucleosynthesis in stars. Although experimental data of the particle emissions following after beta-decays and muon captures have been reproduced with some phenomenological models, the detailed mechanism with respect to the nuclear structure is still unclear. In particular, experimentally measured neutron spectra after muon capture cannot be reproduced well with a nuclear structure model. In this work, we go into the investigation on this issue with a microscopic approach of proton-neutron random-phase-approximation and particle evaporation models considering pre-equilibrium and compound process.

Event date： 2022.5

Language：English  

Country：Japan  

Predictions of $eta$-decay half-lives and neutron capture cross sections of neutron-rich nuclei
To understand $r$-process nucleosynthesis, $eta$ decay half-lives and neutron capture cross sections of neutron-rich nuclei are the important information. Half-lives of many unstable nuclei have been measured using with RI beam, while neutron-capture cross sections remain unexplored experimentally. Even for half-lives, a lot of nuclei that are relevant to the $r$-process are not measured yet. From this respect, numerical data predicted by theoretical models play an important role and have been embedded in $r$-process simulations. We recently calculated the half-lives systematically in neutron-rich regions by a newly developed model using a Bayesian approach to improve the prediction power of the theoretical model. We present in this talk our result of half-life comparing with results of other models. We also discuss neutron capture cross sections of neutron-rich nuclei estimated with a Bayesian approach and its future perspectives.

Event date： 2022.5

Language：Japanese  

Venue：茨木   Country：Japan  

Theoretical prediction of neutron capture cross sections of neutron-rich nuclei at keV region

Event date： 2022.5

Language：English  

Venue：京都大学   Country：Japan  

Nuclei can be at an excited state by muon captures. If the excitation energy is above particle threshold energies, the nuclei emit neutrons and other light particles competing with the gamma deexcitation. The information is important for evaluating soft errors of semi-conductors. Although experimental data of the particle emissions following after muon captures have been reproduced with some phenomenological models, the detailed mechanism with respect to the nuclear structure is still unclear. In particular, experimentally measured neutron spectra after muon capture cannot be reproduced well with a nuclear structure model. In this work, we go into the investigation on this issue with a microscopic approach of proton-neutron random-phase-approximation (RPA) and particle evaporation models considering pre-equilibrium and compound process. We discuss an importance of continuum states of outgoing neutrons in the scheme of RPA.

Event date： 2022.5

Language：English  

Venue：Orsay   Country：France  

Nuclei can be at an excited state by beta-decays and muon captures. If the excitation energy is above particle threshold energies, the nuclei emit particles competing with the gamma deexcitation. The typical examples are neutron emissions after beta-decays and muon captures. In addition, it is known that proton and alpha particle emissions occur for a highly excited neutron-deficient nuclei. The information is important not only for estimating delayed neutrons that play an important role for a stable operation of reactors, but also for evaluating radioactivities, soft errors of semi-conductors, and nucleosynthesis in stars. Although experimental data of the particle emissions following after beta-decays and muon captures have been reproduced with some phenomenological models, the detailed mechanism with respect to the nuclear structure is still unclear. In particular, experimentally measured neutron spectra after muon capture cannot be reproduced well with a nuclear structure model. In this work, we go into the investigation on this issue with a microscopic approach of proton-neutron random-phase-approximation and particle evaporation models considering pre-equilibrium and compound process.

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Event date： 2022.5

Language：English  

Venue：Wako   Country：Japan  

To understand $r$-process nucleosynthesis, $\beta$ decay half-lives and neutron capture cross sections of neutron-rich nuclei are the important information. Half-lives of many unstable nuclei have been measured using with RI beam, while neutron-capture cross sections remain unexplored experimentally. Even for half-lives, a lot of nuclei that are relevant to the $r$-process are not measured yet. From this respect, numerical data predicted by theoretical models play an important role and have been embedded in $r$-process simulations. We recently calculated the half-lives systematically in neutron-rich regions by a newly developed model using a Bayesian approach to improve the prediction power of the theoretical model. We present in this talk our result of half-life comparing with results of other models. We also discuss neutron capture cross sections of neutron-rich nuclei estimated with a Bayesian approach and its future perspectives.

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Event date： 2022.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：岡山(online)   Country：Japan  

Theoretical predictions of beta decay half-lives of neutron-rich nuclei within HFB+QRPA approach

Event date： 2022.3

Language：Japanese  

Venue：茨木   Country：Japan  

Muon capture reaction shown by nuclear structure

Event date： 2022.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：神戸(online)   Country：Japan  

Nuclear data evaluation for JENDL-5, 5; Decay data sublibrary

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：札幌(online)   Country：Japan  

The Optimization of the optical potential for nucleon-nucleus scattering by using coupled-channel optical model, 2

Event date： 2021.9

Language：Japanese  

Venue：online   Country：Japan  

Delayed neutrons and delayed fission for heavy neutron-rich nuclei

Event date： 2021.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京(online)   Country：Japan  

Analysis of radioisotope production using accelerator neutron sources by PHITS and cross section data
Study for radioisotopes (RIs) production using accelerator neutron sources plays an important role in development of production method to supply stably RIs for medical use. We measured yields of not only $^{67,64}$Cu produced by neutrons but also $^{67,66}$Ga by protons in $^{68}$ZnO samples irradiated by neutrons from $^{9}$Be(d,n) reaction with 40-50 MeV deuterons, and developed a powerful method to estimate the yields using a general purpose Monte Carlo particle transport simulation mode PHITS with cross section data of the (d,n) reaction and JENDL-4.0/HE. We found a good agreement between new measured yields and estimated results within a factor of 3. Furthermore, we experimentally observed that yields of $^{67,66}$Ga are enhanced by covering the samples with polyethylene blocks. However, PHITS cannot reproduce the enhancement probably due to insufficient description of scattered neutrons form the blocks in the calculation.

Event date： 2021.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京(online)   Country：Japan  

The Optimization of the optical potential for nucleon-nucleus scattering by using coupled-channel optical model

Event date： 2020.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡(online)   Country：Japan  

Towards the future; Explore science from nuclear data

Event date： 2020.9

Language：Japanese  

Venue：福岡(online)   Country：Japan  

Dependence of fission barrier on pairing correlation in Relativistic Mean-Field theory

Event date： 2020.8

Language：English  

Country：Austria  

Status and perspectives of JENDL fission product yield data

Event date： 2020.2

Language：Japanese  

Venue：神戸   Country：Japan  

About the future that current nuclear physists should go toward

Event date： 2020.2

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Role of the nuclear force on Gamow-Teller transitions

Event date： 2019.10

Language：English  

Country：Japan  

Systematical calculation of $eta$-decay of neutron-rich nuclei by QRPA method using a finite-range $pn$ pairing force

Event date： 2019.9

Language：Japanese  

Venue：山形   Country：Japan  

Systematical calculation of $eta$-decay of neutron-rich nuclei by QRPA method using a finite-range $pn$ pairing force

Event date： 2019.5

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Calculation of most probable atomic number by Skyrme HF-BCS

Event date： 2019.5

Language：Japanese  

Venue：京都   Country：Japan  

A New calculation approach for neutron capture cross sections in neutron-rich region

Event date： 2019.3

Language：Japanese  

Venue：札幌   Country：Japan  

Systematic study of $eta$-decay calculation and future perspectives

Event date： 2019.3

Language：Japanese  

Venue：水戸   Country：Japan  

Reduction and resource recycling of high-level radioactive wastes through nuclear transmutation, 5-1; Development of nuclear data library JENDL/ImPACT-2018 for nuclear transmutation of LLFP
Treatment of high-level radioactive wastes produced by reactor operation is are very important problem for nuclear energy. A new nuclear data library JENDL/ImPACT-2018 has been developed as a part of the ImPACT project aiming at reduction and resource recycling of LLFPs through nuclear transmutation. Due to possible creation of a lot of secondary products including unstable nuclei, the nuclear reaction data have been evaluated with improving predictability of theoretical calculations.

Event date： 2019.3

Language：Japanese  

Venue：水戸   Country：Japan  

Construction of CHART of the nuclides 2018

Event date： 2019.3

Language：Japanese  

Venue：札幌   Country：Japan  

中性子捕獲反応と$\beta$崩壊は、星の中の元素合成で重要な役割を演じている。提案されている様々な元素合成プロセスの中で、特に$r$プロセスに関連する原子核のほとんどは、核図表の安定線から離れた中性子過剰領域にある。そのため元素合成研究では、安定線近傍の原子核だけではなく、核図表の広い範囲の原子核の中性子捕獲反応と$\beta$崩壊の核データを整備することが求められている。しかし、中性子過剰領域の原子核を実験的に測定することは容易ではないため、理論的アプローチによるデータ予測が必要となる。本発表では$\beta$崩壊に着目し、これまで世界各国のグループで行われてきた理論研究の成果と核データへの応用例をまとめるとともに、原子力機構で実施した微視的モデルによる$\beta$崩壊計算の研究成果について発表をする。また、$\beta$崩壊に伴って発生する遅発中性子放出も$r$プロセスに重要であるため、微視的モデル計算と統計モデルを組み合わせた最新の成果について発表をする。さらに、現在の理論モデルによる$\beta$崩壊計算の問題点(予測精度の検証、高次の効果の導入等)について提起し、その具体的解決策についても提案する。

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Event date： 2018.12

Language：English  

Country：Japan  

Nuclear data evaluation for long-lived fission product nuclei with new theoretical approaches

Event date： 2018.10

Language：English   Presentation type：Oral presentation (general)  

Country：Other  

There are various theoretical works based on mean-field theory + quasiparticle random phase approximation (QRPA) calculating $eta$-decay half-lives of nuclei. For the moment, they are the only approaches that are based on a microscopic theory applicable for the systematical calculation in the nuclear chart. A special attention is needed when calculating odd nuclei because of the presence of core polarization effect (CPE). However, the systematical calculation of aforementioned microscopic theories has approximated the calculation of odd nuclei in a simple way. This may cause a problem when predicting unmeasured half-lives, delayed neutron (DN) emission probabilities, etc. For this background, the CPE on $eta$-decay and DN are investigated. We assume that odd nucleus consists of active even-even nucleus and valence particle(s), and use a perturbation theory to estimate the CPE. Core phonon states to be excited are calculated by HFB + QRPA. We found the CPE mitigates an odd-even straggling of half-lives found in no CPE calculations, which is consistent with experiments.

Event date： 2018.10

Language：English  

Venue：Waikoloa  

There are various theoretical works based on mean-field theory + quasiparticle random phase approximation (QRPA) calculating $\beta$-decay half-lives of nuclei. For the moment, they are the only approaches that are based on a microscopic theory applicable for the systematical calculation in the nuclear chart. A special attention is needed when calculating odd nuclei because of the presence of core polarization effect (CPE). However, the systematical calculation of aforementioned microscopic theories has approximated the calculation of odd nuclei in a simple way. This may cause a problem when predicting unmeasured half-lives, delayed neutron (DN) emission probabilities, etc. For this background, the CPE on $\beta$-decay and DN are investigated. We assume that odd nucleus consists of active even-even nucleus and valence particle(s), and use a perturbation theory to estimate the CPE. Core phonon states to be excited are calculated by HFB + QRPA. We found the CPE mitigates an odd-even straggling of half-lives found in no CPE calculations, which is consistent with experiments.

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Event date： 2018.9

Language：Japanese  

Venue：京都   Country：Japan  

Measurement and estimation of the $^{99}$Mo production yield by the acceleration neutron

Event date： 2018.9

Language：Japanese  

Venue：岡山   Country：Japan  

Incident neutron energy dependence of delayed neutron yields using the latest decay data

Event date： 2018.6

Language：Japanese  

Venue：和光   Country：Japan  

A Study of $eta$-decay and delayed neutron based on microscopic nuclear structure model for applications
While mean-field theory has been extensively applied in nuclei on the nuclear chart, majority of nucleus investigated has been limited to even-one. This would be because a relatively simple picture of even-nuclei and easiness to handle with mean-field theory. The shortcoming which the mean-field theory is not able to calculate odd nuclei properly is a barrier to apply the theory to studies of nuclear data and nucleosynthesis. To overcome this problem, we worked on two-body and three-body models applicable to odd-nuclei (either proton or neutron numbers is odd). We calculated Gamow-Teller states with this model, and estimated beta-decay half-lives and delayed neutron branching ratios. The obtained results reproduced the experimental data better than a conventional approach. We also discuss future perspectives of nuclear physics for applications to sciences demanding accurate theoretical predictions like nucleosynthesis.

Event date： 2018.6

Language：English  

Country：Japan  

Effect of two-particle two-hole excitations in target nuclei on inelastic differential cross sections
A picture of nuclear excited states can be discribed by 1p1h excitation. Experimental data of inelastic scatterings are reasonably reproduced theoretically in this picture. However, it is known that higher-order configurations are important for a better insight of the excited states. This may apply to the inelastic scattering. However, the relation between higher-order configuration and inelastic scattering is not clear. To clarify the relation, we consider 2p2h excitation of target nuclei and focus on the differential cross sections. The 2p2h states of target nuclei are calculated by SRPA. The reaction process is calculated by DWBA. As a reaction channel, inelastic scattering and (p,n) reaction are chosen. It turned out that the diffraction patterns of the differential cross section considering 2p2h were not significantly different from those considering 1p1h although the absolute values were smaller than 1p1h calculation. We discuss it from the nuclear structural point of view.

Event date： 2018.6

Language：Japanese  

Venue：和光   Country：Japan  

While mean-field theory has been extensively applied in nuclei on the nuclear chart, majority of nucleus investigated has been limited to even-one. This would be because a relatively simple picture of even-nuclei and easiness to handle with mean-field theory. The shortcoming which the mean-field theory is not able to calculate odd nuclei properly is a barrier to apply the theory to studies of nuclear data and nucleosynthesis. To overcome this problem, we worked on two-body and three-body models applicable to odd-nuclei (either proton or neutron numbers is odd). We calculated Gamow-Teller states with this model, and estimated beta-decay half-lives and delayed neutron branching ratios. The obtained results reproduced the experimental data better than a conventional approach. We also discuss future perspectives of nuclear physics for applications to sciences demanding accurate theoretical predictions like nucleosynthesis.

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Event date： 2018.4

Language：English  

Country：Japan  

Three-body model for Odd-Odd nuclei; What of them did core excitations change?
While mean-field theory has been extensively applied in nuclei on the nuclear chart, majority of nucleus investigated has been limited to even-one. This would be because a relatively simple picture of even-nuclei and easiness to handle with mean-field theory. Recently, various fields such as astrophysics, nuclear engineering, and so on, require a knowledge of nuclear physics and theoretical calculations of a structure information on odd-nuclei as well as even-nuclei are demanded. To meet the requests, one has to extend the mean-field theory so that it is able to depict odd-nuclei in a simple picture and reproduce experimental data with a high accuracy. In this work, we present a three-body model for odd-nuclei (proton and neutron numbers are odd) based on mean-field theory, and discuss the results. We also give a discussion about core excitation and its effects on resonance width and transition probabilities.

Event date： 2018.3

Language：Japanese  

Venue：吹田   Country：Japan  

Calculation of cross section in resonance region using the statistical properties of the resonance parameters
Except for extremely light nuclei and neutron rich nuclei, generally the density of nuclear excited states around neutron threshold energy is very high, and therefore it is very difficult to predict energy and width of resonance precisely. On the other hand, it has been known that the resonance parameters have statistical property with high density of excited states. There is a theoretical method to calculate cross section in resonance region by generating resonance parameters randomly utilizing the statistical properties of the resonance parameters. Such a method can reflect a theoretical information of resonance on a nuclear data evaluation for nuclei with no experimental data, such as fission products. However, studies for how to determine a representative value of the cross section randomly calculated, and what is an uncertainty from the randomness, are insufficient. Therefore, in this study, we calculated the cross section in the resonance region using randomly generated resonance parameters, and derived the probability distribution of the cross section by calculating cross section repetitively using resonance parameter sets generated from different random seeds. By using this density distribution, we discuss the behavior of the statistically reasonable cross section, and uncertainty from statistical fluctuation.

Event date： 2017.9

Language：Japanese  

Venue：札幌   Country：Japan  

Development of nuclear transmutation methods for converting LLFP into stable or short-lived nuclides, 15; Level densities of LLFPs and nuclei around LLFPs calculated based on the microscopic structure calculation
To establish a reasonable nuclear transmutation technology for long-lived fission products (LLFPs), it is important to improve precision of the nuclear data needed for the simulation of the nuclear transmutation. The level density is essential for the nuclear reaction calculation using the statistical model, and it has significant influence on the precision of the nuclear data evaluation. Although a phenomenological model such as Fermi Gas model is used in a usual nuclear data evaluation, it is considered that using a microscopic theory that has predictive power superior to a phenomenological model brings better precision for the nuclear data. In this study, to improve precision of the nuclear data of LLFPs and nuclei around LLFPs, the level densities needed for the nuclear data evaluation of those nuclei were derived based on the microscopic nuclear data calculation. In this derivation, we improved the calculation method to describe prcisely the effect of the deformation change with nuclear excitation. To analyze precision of the nuclear reaction calculation, we compared the cross sections of various reaction channel systematically with the experimental data of stable nuclei.

Event date： 2017.9

Language：Japanese  

Venue：札幌   Country：Japan  

Development of nuclear transmutation methods for converting LLFP into stable or short-lived nuclides, 16; Development of nuclear data library for the ImPACT project
Under the ImPACT program of nuclear transmutation, we are developing a new nuclear data library that includes nuclear data of 4 main LLFPs ($^{79}$Se, $^{93}$Zr, $^{107}$Pd, $^{135}$Cs) and surrounding nuclei. To improve accuracy of nuclear data for unstable nuclei whose experimental data are scarce, microscopic nuclear structure theories was used to deduce nuclear level density and $gamma$-ray strength function. They were applied to evaluation of cross sections for neutron and proton induced reactions up to 200 MeV. Status of development of the library including evaluation methods and results is reported.

Event date： 2017.7

Language：English  

Country：Japan  

Development of nuclear data evaluation method to improve precision of nuclear data for long-lived fission products

Event date： 2017.5

Language：English   Presentation type：Oral presentation (general)  

Country：Norway  

Interaction dependence of the nuclear level density calculated using Hartree-Fock-Bogoliubov theory
While Fermi Gas type phenomenological models are widely used to calculate the nuclear level density (NLD) of stable nuclei, it is important to develop a microscopic method to achieve reliable NLD for unstable nuclei. One of microscopic methods to calculate NLD is that based on the microscopic nuclear structure calculation using Hartree-Fock-Bogoliubov (HFB) theory. Since a effective nuclear interaction is basically the only input in HFB calculation, we investigated how the calculated NLD depends on it with special attention to the adopted pairing interaction, to discuss about the reliability of this method. Adding to SkM* force that was used in our previous study, SLy4, SkP, and UNEDF1 forces were used in HFB calculations of the present study. The statistical method was applied to derive NLD based on HFB calculation. We compared the s-wave resonance spacing D$_0$ derived from the calculated NLD with the experiments, and found better agreement with the results with SkP and UNEDF1 forces compared to those with SkM and SLy4 forces.

Event date： 2017.3

Language：Japanese  

Venue：豊中   Country：Japan  

Interference effect between neutron direct and resonance capture reactions for neutron-rich nuclei

Event date： 2017.3

Language：Japanese  

Venue：平塚   Country：Japan  

Calculations of cross sections using the nuclear level density obtained from the microscopic nuclear structure calculation
Nuclear reaction calculations using the statistical model require information of the nuclear level density. While the phenomenological models such as Fermi Gas model are often used to calculate the nuclear level density in usual nuclear data evaluations, reliability of such level density depends on parameter adjustments using experimental values. Therefore, development of microscopic calculation methods that does not depend on parameter adjustments is desired. One of the microscopic methods to calculate the nuclear level density is the combinatorial method that uses single-particle levels obtained from Hartree-Fock theory, and its reliability has been discussed through the reproducibility of the s-wave neutron resonance spacing $D_0$. However, comparisons of cross sections with experiments are only preformed for (n,$gamma$) reaction of some nuclei, and is still insufficient. Therefore, in this work, we calculate the nuclear level density using the combinatorial method, and apply it to the nuclear reaction calculations such as (n,$gamma$) reaction and (n,2n) reaction calculations. The cross sections of these reactions adding to the s-wave neutron resonance spacing $D_0$ for stable nuclei are compared with the experiments systematically, and then the reliability of the nuclear level density is discussed.

Event date： 2016.12

Language：English  

Country：Japan  

Second proton-neutron random phase approximation studied by the Lipkin model in the SU(4) basis
The random phase approximation (RPA) is one of the useful approaches to describe a collective motion of nuclei. However, RPA intrinsically considers only 1 particle-1 hole (1p1h) excitations, as a result it fails to describe the width of the excited states, for example the Gamow-Teller (GT) state. To include higher-order particle-hole excitations, one can extend RPA to Second RPA (SRPA) which includes 2p2h excitations in a similar way to RPA with the quasi-boson-approximation (QBA). However, it fails to describe the GT distribution even with those model. A part of the problem may arise from the use of QBA. In past studies, SRPA was compared with exact solution using the Lipkin Model and the validity of application of QBA to them was examined. In this work, we examine proton-neutron SRPA (pnSRPA) in SU(4) basis. SU(4) is naturally required in this case to take into account two different particles having two levels each. The first and second excited states are calculated by the diagonalization of Hamiltonian and pnSRPA.

Event date： 2016.10

Language：English  

Country：Japan  

Reduction and resource recycling of high-level radioactive wastes through nuclear transformation; Theoretical predictions of the nuclear reaction data for nuclei involved in the nuclear transformation system
For the feasibility study of the nuclear transmutation system for the long-lived fission products(LLFPs), the simulation calculation to estimate the efficiency of the transmutation system is essential. The precision of the simulation calculation largely depends on the evaluated nuclear data used in the calculation. To improve the precision of the simulation calculation, developing nuclear data not only of LLFPs but also of all the nuclei involved in the simulation calculation is desirable. When we study the transmutation system using the nuclear reaction such as spallation reaction, it is anticipated that a wide range of nuclei including unstable nuclei with no or scarce experimental are produced. In particular, the shortage of nuclear experimental data in resonance region is a problem for nuclear data evaluation, because it is difficult to predict the resonant structure precisely in a theoretical way. One of the methods mitigating this problem is to use the resonance parameters randomly determined from the statistical properties of the resonance parameters. This approach is already adopted in TENDL nuclear data library. However, the cross section calculated using such a method would have a large uncertainty arising from the statistical fluctuation of the resonance parameters in principle. This uncertainty wasn't discussed in the previous study. In this study, we investigated the statistical method to predict the nuclear reaction data in resonance region focusing on its statistical uncertainties. Particularly, we shall discuss the neutron capture cross sections of nuclei expected to be produced via the transmutation of Se-79, Zr-93, Pd-107 and Cs-135.

Event date： 2016.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：新潟   Country：Japan  

Medical radioisotope production with accelerator neutrons by 50 MeV deuterons

Event date： 2016.9

Language：Japanese  

Venue：久留米   Country：Japan  

Calculation of nuclear level density using the microscopic statistical model with Hartree-Fock-Bogoliubov theory
The nuclear level density is essential for nuclear reaction calculations using the statistical model and pre-equilibrium models. Phenomenological Fermi gas models have been used widely for calculations of the nuclear level density, however, reliability of them depend on the parameter adjustment to reproduce the experimental informations of the s-wave neutron resonance spacing D0, and therefore, calculations using more microscopic models are desirable for unstable nuclei that have no available experimental information. The microscopic statistical models and combinatorial models based on Hartree-Fock theory are models that can reproduce the experimental D0 with precisions comparable to the phenomenological models. However, these calculations are strongly dependent on the strength of the pairing interaction, and its uncertainty affect to the precision of the calculations. Therefore, in this work, we improved the treatment of the pairing interaction in the nuclear structure calculation, and analyzed how the pairing interaction affect to the precision of the nuclear level density calculation.

Event date： 2016.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：仙台   Country：Japan  

To establish the nuclear transmutation system for the long-lived fission products (LLFPs), it is desired to improve precision of the simulation calculation for the transmutation system. To achieve this, nuclear data of various nuclei produced via the nuclear transmutation of LLFPs are also important. However, it is expected that unstable nuclei with no available experimental data are produced via the nuclear transmutation. One of the physical quantity that is very difficult to predict with no experimental data is the thermal neutron capture cross section. The thermal neutron capture cross section is dominated by the energy and width of the first resonance, and slight variation of them can change the thermal neutron capture cross section drastically. While it is very difficult to determine them with high precision, it is known that a resonance width follows Porter-Thomas distribution because of complexity and randomness of a nuclear structure, and a resonance spacing follows Wigner distribution. In this work, we calculate the thermal neutron capture cross section by using the statistical property of the resonance parameters with Monte Carlo method. The calculation result is obtained as a probability distribution of the thermal neutron capture cross section. We calculated approximately 250 nuclei that have experimental data, and found that the dispersion of the experimental data is well explained by the calculated probability distribution.

Event date： 2016.3

Language：Japanese  

Venue：仙台   Country：Japan  

Theoretical study of hallway state via charge exchange reaction

Event date： 2016.3

Language：English  

Country：Japan  

Study on quenching of the Gamow-Teller transitions by Second-Tamm-Dancoff-Approximation
Two-particle two-hole (2p2h) effect on Gamow-Teller (GT) transition for neutron-rich nuclei is studied by the second Tamm-Dancoff-Approximation (STDA) with the Skyrme interaction. Unstable $^{24}$O and $^{34}$Si, and stable $^{48}$Ca nuclei are chosen to study quenching and fragmentation of the GT strengths. The correlation of 2p2h configurations induces 20% quenching and downward shift of GT giant resonances (GTGRs). The residual interaction exchanging angular momentum by $Delta L=2$, appeared in the tensor force part as well as the central force part, gives a meaningful effect to the GT distributions. 15 to 20% of the total GT strengths are brought to high energy region above GTGRs. In particular, the tensor force brings strengths to high energy more than 60 MeV. STDA calculation with a small model space for 2p2h configuration is also studied and experimental data of $^{48}$Ca is reproduced successfully.

Event date： 2016.3

Language：Japanese  

Venue：仙台   Country：Japan  

Making of beta decay database by quasiparticle random phase approximation

Event date： 2016.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：仙台   Country：Japan  

Study for uncertainty reduction of FP decay heat of FBR fuel

Event date： 2016.2

Language：English  

Country：Japan  

Introduction of nuclear data and related topics
"Nuclear data" compiles a variety of information on nuclei such as reaction cross sections and radioactivities. The data is widely applied to many fields concerning nuclear reaction and decay. For example, safety assessment and decommissioning of nuclear reactor, accelerator-related physics, medical RI production, and assessment of environmental radioactivity. The nuclear data is compiled, respecting experimental data in principle. However, a large part of it is consisted of numerical calculation based on the nuclear theory. It is therefore one of the fields that the nuclear theory as well as experiment play an important role in society. This talk will introduce how the nuclear theory is used in the nuclear data about nuclear reaction and beta-decay. A recent development about charge-exchange reaction calculation to produce more accurate nuclear data will be also shown.

Event date： 2015.11

Language：Japanese  

Venue：つくば   Country：Japan  

Gamow-Teller transition and its tensor correlation

Event date： 2015.9

Language：Japanese  

Venue：大阪   Country：Japan  

Study of 2p2h effect on the Gamow-Teller transition with Skyrme Second Tamm-Dancoff-Approximation

Event date： 2015.9

Language：Japanese  

Venue：静岡   Country：Japan  

High-energy nuclear data library JENDL-4.0/HE
Neutron- and proton-induced evaluated nuclear data are required in a wide energy range for the design of accelerator applications. New evaluations are performed with recent progresses in the optical and pre-equilibrium model calculations. We also evaluated cross-sections for p + $^{6,7}$Li and p + $^{8}$Be which are highly requested from medical field. Our present high-energy nuclear data library, JENDL-4.0/HE, includes cross-sections for 132 nuclei up to 200 MeV. In this talk, we present the evaluation methods, evaluated double-differential cross-sections and results of benchmark calculations.

Event date： 2015.8

Language：Japanese  

Venue：東京   Country：Japan  

Nuclear cross section data for astrophysical research

Event date： 2015.3

Language：Japanese  

Venue：日立   Country：Japan  

Evaluation of nuclear data for high energy neutron and proton induced reactions
To extend the energy range of JENDL-4.0, nuclear data for neutron and proton induced reactions have been evaluated up to 200 MeV for medium-heavy nuclei. The nuclear reaction model calculation code CCONE, which was used for development of JENDL-4.0, was used. The code was upgraded on models for the pre-equilibrium process. The results improve consistency with the experimental data on particle emission spectra and isotope production cross sections. Evaluated results will be reported.

Event date： 2015.3

Language：Japanese  

Venue：日立   Country：Japan  

Construction of CHART of the nuclides 2014

Event date： 2014.12

Language：English  

Country：Japan  

Sensitivity analysis of delayed neutron with JENDL/FPD-2011 and JENDL/FPY-2011

Event date： 2014.11

Language：English  

Venue：札幌   Country：Japan  

Sensitivity of delayed neutron to fission yields and beta-decay half-lives
Delayed neutron yields of U-235, -238 and Pu-239 were estimated by aggregate calculation with the JENDL FP Decay Data File 2011 and JENDL FP Fission Yields Data File 2011. The sensitivity of delayed neutron to the fission yields and beta-decay half-lives were also investigated. It is found that delayed neutron of U-235 is sensitive to accuracies of fission yields and half-lives of several nuclei. In addition, there are nuclei which play an important role with respect to either fission yields or half-lives. This result gives a list of prior precursors to be measured to experimental groups and will be useful for making next fission yields data file and FP decay data file.

Event date： 2014.11

Language：Japanese  

Venue：木津川   Country：Japan  

Nuclear resonance fluorescence measurements by linearly polarized photon beam
Nuclear electric or magnetic dipole transitions can be studied by nuclear resonance fluorescence (NRF). The NRF process takes place via only the electromagnetic (EM) interaction. Since the EM interaction is well-known, the information on the nuclear dipole excitation can be obtained in a nuclear model-independent way. We used a quasi-monochromatic, linearly polarized photon beam produced by inverse Compton scattering of laser light with high energy electrons at the NewSUBARU electron storage ring facility of Hyogo University. A natural Cr target with a 1-cm diameter and a 3-cm length was irradiated by photon beams with the maximum energies of 8.2, 8.8, 9.4, 10, 11, and 12 MeV. Scattering photons were measured by three high purity Ge detectors with relative efficiencies of 100 to 140%. Two of the Ge detectors were horizontally or vertically placed at the scattering angle of 90$^{circ}$. The polarization of the photon beams was fixed to the horizontal plane.

Event date： 2014.11

Language：English  

Venue：札幌   Country：Japan  

Delayed neutron yields of U-235, -238 and Pu-239 were estimated by aggregate calculation with the JENDL FP Decay Data File 2011 and JENDL FP Fission Yields Data File 2011. The sensitivity of delayed neutron to the fission yields and beta-decay half-lives were also investigated. It is found that delayed neutron of U-235 is sensitive to accuracies of fission yields and half-lives of several nuclei. In addition, there are nuclei which play an important role with respect to either fission yields or half-lives. This result gives a list of prior precursors to be measured to experimental groups and will be useful for making next fission yields data file and FP decay data file.

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Event date： 2014.11

Language：Japanese  

Venue：木津川   Country：Japan  

Nuclear electric or magnetic dipole transitions can be studied by nuclear resonance fluorescence (NRF). The NRF process takes place via only the electromagnetic (EM) interaction. Since the EM interaction is well-known, the information on the nuclear dipole excitation can be obtained in a nuclear model-independent way. We used a quasi-monochromatic, linearly polarized photon beam produced by inverse Compton scattering of laser light with high energy electrons at the NewSUBARU electron storage ring facility of Hyogo University. A natural Cr target with a 1-cm diameter and a 3-cm length was irradiated by photon beams with the maximum energies of 8.2, 8.8, 9.4, 10, 11, and 12 MeV. Scattering photons were measured by three high purity Ge detectors with relative efficiencies of 100 to 140\%. Two of the Ge detectors were horizontally or vertically placed at the scattering angle of 90$^{\circ}$. The polarization of the photon beams was fixed to the horizontal plane.

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Event date： 2014.10

Language：English  

Country：Other  

Radioisotope productions for medical use with accelerator neutrons
Various kinds of radioactive isotopes (RIs) are widely used in nuclear medicine for diagnostics and therapy. Since the RIs are not usually present in the nature, they must be produced by nuclear reactors and accelerators. For instance, $^{99m}$Tc is mainly produced by fission of highly enriched $^{235}$U (HEU) in nuclear reactors. However, use of the HEU is unfavorable in terms of nuclear security. Therefore, many methods without $^{235}$U have been studied in order to produce RIs for medical use; for example, thermal neutron capture, $gamma$ disintegration, and proton induced reactions. We also have proposed an alternative method using accelerator neutron besides the above methods. In this talk, we will show the features of RI productions with accelerator neutron which we have ever investigated and found, along with numerical results of RI yields calculated with Japanese Evaluated Nuclear Data Library (JENDL-4.0).

Event date： 2014.9

Language：Japanese  

Venue：京都   Country：Japan  

Measurements of E1 and M1 multipolarity of Cr-52 using nuclear resonance fluorescence
Mono-energetic and linearly polarized (LCS) $gamma$-rays can be generated by Compton scattering of laser light with high energy electrons. In nuclear resonance fluorescence (NRF), spins of the excited states and their transition probabilities can be extracted in a model independent way. In addition, by using high polarization of LCS $gamma$-rays, it is possible to precisely determine multipolarity (E1 or M1) of the NRF $gamma$-rays, i.e., parities of the excited states. We have performed NRF measurements at the NewSUBARU electron ring facility of University of Hyogo. LCS $gamma$-rays with maximum energies of 8.2, 8.8, 9.4, 10, 11, and 12 MeV were used to irradiate a natural Cr target. From results of the measurements we have determined the parities of the excited states below the neutron separation energy of about 12 MeV. In this paper, we will report the results of the measurements and the comparison of the dipole strength distribution with the RPA calculation.

Event date： 2014.7

Language：English  

Country：Other  

Background contributions of NRF-based nondestructive assay for spent nuclear fuel
It is required to measure spent nuclear fuel as accurate as possible for nuclear material management concerning nuclear security and safeguards. The system performance such as counting precision for the $gamma$-ray nondestructive assay (NDA) based on nuclear resonance fluorescence (NRF) would be affected by radiation backgrounds from spent fuel. Generally, the $gamma$-ray spectrum of radiation backgrounds from spent fuel has characteristic shape with an exponential fall-off as a function of $gamma$-ray energy. Therefore, the NRF measurement at higher energies is preferable to obtain a better signal-to-noise ratio. The counting precision is also affected by backgrounds from the coherent scattering such as Rayleigh, nuclear Thomson, and Delbruck scattering. In order to minimize the Coherent scattering contribution, we propose a method in which NRF transitions to the first excited state is measured. We calculated the radiation background counts from spent fuel as well as the coherent scattering background. Assuming various cross sections for NRF in the range of 3 to 100 eV barn at excitation energies of 2 to 5 MeV, we have estimated the statistical uncertainties of the proposed NDA system. We also discuss the NRF strength based on the previous experimental data as well as theoretical prediction by quasi-particle random phase approximation (QRPA).

Event date： 2014.6

Language：English  

Country：Japan  

Study of $eta$ delayed neutron with proton-neutron QRPA plus statistical model
Delayed neutron is one of factors for stable and safe operation of a nuclear reactor. Energy spectra of delayed neutron and neutrino emitted in beta-decay attract another interest in a connection with nuclear security, non-destructive analysis, and nuclear nonproliferation. Because of limitation of experiment of short-lived nuclei, a complementary work with theoretical approach is well-suited to complete a delayed neutron data. To this end, theoretical hybrid model using pnQRPA and Hauser-Feshbach statistical model is constructed. The present results of delayed neutron are compared with other theoretical models. It is found that the present model reproduces experimental data in a comparable level to the other models. The energy spectra of delayed neutron are also compared and discussed. We conclude that the present approach can be one of theoretical tools to provide a reliable beta-delayed neutron calculation of experimentally unmeasured neutron-rich nuclei.

Event date： 2014.4

Language：Japanese  

Venue：東海   Country：Japan  

Calculation of Beta Decay Half Lives with microscopic pnQRPA method; Extension to odd nuclei by 1 quasi-particle state

Event date： 2014.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Nuclear resonance fluorescence measurements using laser Compton scattering $gamma$-ray beam at the NewSUBARU synchrotron radiation facility
A mono-energetic $gamma$-ray beam can be generated by collision of high-energy electrons with laser photons. The laser Compton $gamma$-ray beam has excellent properties in monochromaticity and polarization. It is therefore possible to make unambiguous determination of parities of excited states in nuclear resonance fluorescence (NRF) experiments. We measured NRF $gamma$-rays on Cr, Pb, and Bi targets. In this talk, we will report on the experimental setup and the results of the measurement.

Event date： 2014.3

Language：Japanese  

Venue：平塚   Country：Japan  

Study of $eta$-delayed neutron and emitted neutron spectra with deformed proton-neutron QRPA plus statistical model

Event date： 2014.3

Language：Japanese  

Venue：和光   Country：Japan  

Application of nuclear data to production of RI using neutrons generated by an accelerator

Event date： 2014.3

Language：Japanese  

Venue：平塚   Country：Japan  

Impact of tensor force on $eta$ decay of magic and semimagic nuclei

Event date： 2014.3

Language：Japanese  

Venue：東京   Country：Japan  

A mono-energetic $\gamma$-ray beam can be generated by collision of high-energy electrons with laser photons. The laser Compton $\gamma$-ray beam has excellent properties in monochromaticity and polarization. It is therefore possible to make unambiguous determination of parities of excited states in nuclear resonance fluorescence (NRF) experiments. We measured NRF $\gamma$-rays on Cr, Pb, and Bi targets. In this talk, we will report on the experimental setup and the results of the measurement.

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Event date： 2014.1

Language：English  

Country：Japan  

NRF-based NDA of nuclear material using monochromatic $gamma$-ray beam
One of the urgent issues for NDA is to establish a reliable technique for the assay of nuclear materials in spent nuclear fuel. The system performance such as counting precision for the NRF-based NDA, would be affected by radiation backgrounds from spent fuel. Generally, the $gamma$-ray spectrum of radiation backgrounds from spent fuel has characteristic shape with an exponential fall-off as a function of $gamma$-ray energy. Therefore, the NRF measurement at higher energies is preferable to obtain a better signal-to-noise ratio. The counting precision is also affected by backgrounds from the coherent scattering. In order to minimize the Coherent scattering contribution, we propose a method in which NRF transitions to the first excited state is measured. Assuming various cross sections for NRF in the range of 3 to 100 eV barn at excitation energies of 2 to 5 MeV, we have estimated the statistical uncertainties of the proposed NDA system.

Event date： 2014.1

Language：English  

Venue：Tokai   Country：Japan  

One of the urgent issues for NDA is to establish a reliable technique for the assay of nuclear materials in spent nuclear fuel. The system performance such as counting precision for the NRF-based NDA, would be affected by radiation backgrounds from spent fuel. Generally, the $\gamma$-ray spectrum of radiation backgrounds from spent fuel has characteristic shape with an exponential fall-off as a function of $\gamma$-ray energy. Therefore, the NRF measurement at higher energies is preferable to obtain a better signal-to-noise ratio. The counting precision is also affected by backgrounds from the coherent scattering. In order to minimize the Coherent scattering contribution, we propose a method in which NRF transitions to the first excited state is measured. Assuming various cross sections for NRF in the range of 3 to 100 eV barn at excitation energies of 2 to 5 MeV, we have estimated the statistical uncertainties of the proposed NDA system.

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Event date： 2013.12

Language：English  

Country：Japan  

Study of $eta$-decay and $eta$-delayed neutron emission probability with deformed proton-neutron QRPA plus statistical model
Aim of this work is an evaluation of $eta$-delayed neutron and application to nuclear astrophysics. $eta$-decay is calculated with pnQRPA based on Hartree-Fock + BCS in the axially deformed system. Light particle emission probability from highly excited state of daughter nucleus is calculated with Hauser-Feshbach model implemented by CCONE. As a $NN$ interaction, several Skyrme forces are used. Various neutron-rich nuclei relevant to fission fragment and r-process are investigated systematically. We find that half-lives $T_{1/2}$ can be reproduced well with a phenomenological $T=0$ pairing forces. However, delayed neutron emission probabilities $P_n$ give different values among the Skyrme forces, even though they give the same $T_{1/2}$. From the comparison with the experimental data from the ENSDF database, it is found that each Skyrme force has an advantage in different mass regions, which suggests one to use plural Skyrme forces to calculate $P_n$ systematically.

Event date： 2013.12

Language：English  

Venue：Wako   Country：Japan  

Aim of this work is an evaluation of $\beta$-delayed neutron and application to nuclear astrophysics. $\beta$-decay is calculated with pnQRPA based on Hartree-Fock + BCS in the axially deformed system. Light particle emission probability from highly excited state of daughter nucleus is calculated with Hauser-Feshbach model implemented by CCONE. As a $NN$ interaction, several Skyrme forces are used. Various neutron-rich nuclei relevant to fission fragment and r-process are investigated systematically. We find that half-lives $T_{1/2}$ can be reproduced well with a phenomenological $T=0$ pairing forces. However, delayed neutron emission probabilities $P_n$ give different values among the Skyrme forces, even though they give the same $T_{1/2}$. From the comparison with the experimental data from the ENSDF database, it is found that each Skyrme force has an advantage in different mass regions, which suggests one to use plural Skyrme forces to calculate $P_n$ systematically.

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Event date： 2013.3

Language：Japanese  

Venue：東大阪   Country：Japan  

Evaluation of neutron nuclear data of praseodymium isotopes

Event date： 2012.9

Language：Japanese  

Venue：東広島   Country：Japan  

Evaluation of counting precision for nondestructive interrogation of nuclear materials with nuclear resonance fluorescence
Non-destructive interrogation of nuclear materials is an important technique for nuclear security and safeguards. We have proposed a new method using nuclear resonance fluorescence in combination with mono-energetic laser Compton $gamma$-rays. Recently, we evaluated counting precision in nondestructive analysis for nuclear materials in spent fuel. In this talk, we will report the result of the evaluation.

Event date： 2012.3

Language：Japanese  

Venue：西宮   Country：Japan  

Effect of tensor force on energy-weighted sum-rule of M1 transition

Event date： 2012.3

Language：Japanese  

Venue：福井   Country：Japan  

Measurement of thermal-neutron-capture cross section of Ni-62 using multiple prompt $gamma$-ray spectrometer, STELLA
A cold-neutron beam was irradiated on a Ni-62 sample at a JRR-3 guided beam facility in JAEA. Prompt $gamma$-rays from the neutron capture reaction were measured with a multiple $gamma$-ray spectrometer, STELLA. From the analysis of the prompt $gamma$-ray intensities, a thermal-neutron-capture cross section of Ni-62 has been derived.

Event date： 2012.3

Language：Japanese  

Venue：福井   Country：Japan  

A cold-neutron beam was irradiated on a Ni-62 sample at a JRR-3 guided beam facility in JAEA. Prompt $\gamma$-rays from the neutron capture reaction were measured with a multiple $\gamma$-ray spectrometer, STELLA. From the analysis of the prompt $\gamma$-ray intensities, a thermal-neutron-capture cross section of Ni-62 has been derived.

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Event date： 2012.2

Language：English  

Country：Myanmar  

Nuclear collectivity and its role on beta-decay
The nuclear vibration and rotation are strongly related with excited states. They can be described by an idea of collective motion, which indicates that nucleons inside a nucleus coherently contribute the motion. We call its character collectivity. Besides the vibration and rotation, the collectivity plays an important role in beta-decay of a nucleus. Due to the collectivity, beta-decay shows a different characteristic from that of free neutron. We investigate the beta-decay of neutron-rich unstable nuclei within the framework of the random-phase-approximation. We find that the effect of collectivity on the beta-decay half-lives is more important and complex than we have ever known. We also introduce several applications of the work of beta-decay to other research fields.

Event date： 2012.2

Language：English  

Venue：Mandalay   Country：Myanmar  

The nuclear vibration and rotation are strongly related with excited states. They can be described by an idea of collective motion, which indicates that nucleons inside a nucleus coherently contribute the motion. We call its character collectivity. Besides the vibration and rotation, the collectivity plays an important role in beta-decay of a nucleus. Due to the collectivity, beta-decay shows a different characteristic from that of free neutron. We investigate the beta-decay of neutron-rich unstable nuclei within the framework of the random-phase-approximation. We find that the effect of collectivity on the beta-decay half-lives is more important and complex than we have ever known. We also introduce several applications of the work of beta-decay to other research fields.

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Event date： 2011.9

Language：Japanese  

Venue：弘前   Country：Japan  

Role of tensor force on Gamow-Teller and M1 transitions at low energy region

Event date： 2011.9

Language：Japanese  

Venue：北九州   Country：Japan  

Nuclear structure study of Ni-63 using multiple prompt $gamma$-ray spectrometer: STELLA
Prompt $gamma$-rays from the neutron capture reaction of Ni-62 have been measured by using the multiple prompt $gamma$-ray spectrometer, STELLA, installed at the Research Reactor, JRR-3, of Japan Atomic Energy Agency. A highly-excited level structure below the neutron separation energy of 6838 keV in Ni-63 has been reported, including 35 new levels and 272 new $gamma$-ray transitions. The experimentally observed level structure is compared and discussed with a shell model calculation and a Mean-field statistical model calculation.

Event date： 2011.9

Language：Japanese  

Venue：北九州   Country：Japan  

Prompt $\gamma$-rays from the neutron capture reaction of Ni-62 have been measured by using the multiple prompt $\gamma$-ray spectrometer, STELLA, installed at the Research Reactor, JRR-3, of Japan Atomic Energy Agency. A highly-excited level structure below the neutron separation energy of 6838 keV in Ni-63 has been reported, including 35 new levels and 272 new $\gamma$-ray transitions. The experimentally observed level structure is compared and discussed with a shell model calculation and a Mean-field statistical model calculation.

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Event date： 2010.11

Language：Japanese  

Venue：東京   Country：Japan  

Magnetic dipole distributions calculated with the QRPA method for future application to ($gamma$,n) and (n,$gamma$) reaction

Event date： 2010.11

Language：Japanese  

Venue：東京   Country：Japan  

原子核による中性子吸収反応を理論的に再現・予測するためには、中性子吸収後に放出される$\gamma$線の強度が正確にわからなければならない。特に重要な役割を演じているのはE1型遷移によって放出される$\gamma$線であり、その強度関数は現象論的な形でこれまで与えられてきた。最近では原子核の構造を考慮したQRPA法によって導出されたE1型$\gamma$線を用いることで、中性子吸収反応の実験結果をより忠実に再現できるようになってきた。またE1型遷移だけではなく、M1型遷移も低エネルギーの実験データを再現するために重要になっていることがわかってきた。しかしM1型遷移は依然として現象論的な手法に頼っているのが現状である。そこで将来的に($\gamma$,n)及び(n,$\gamma$)反応断面積の理論的な再現・予測を行うためQRPA法を用いて低エネルギーM1強度分布の計算コードを開発した。M1強度の理論計算の不確定要素を検証するため2つのSkyrmeパラメーター(SG2, SV-bas)を用いて比較を行った。また今後の核反応計算コードと融合させて中性子反応断面積の理論計算の予定や、奇数核への拡張についても紹介する。

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Event date： 2010.10

Language：Japanese  

Venue：京都   Country：Japan  

Hypernuclear fission with Skyrme-Hartree-Fock approach

Event date： 2010.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：札幌   Country：Japan  

Microscopic statistical nuclear level density with the Skyrme-Hartree-Fock method

Event date： 2010.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Production amount of $^{99}$Mo by $^{nat}$C(d,n) reaction

Event date： 2010.6

Language：English  

Country：Japan  

Collectivity of low-lying Gamow-Teller strength for tin isotopes
We study the collectivity of low-lying Gamow-Teller (GT) transition from stable to neutron-rich tin isotopes with interest of the microscopic understand of beta-decay in nuclei. Our formalism is based on the proton-neutron quasi-particle random phase approximation (pnQRPA) on the basis of Skyrme-Hartree-Fock+BCS method which has been widely applied to the study of beta-decay. We find that the lowest GT peak for neutron-rich nuclei is almost a single-particle like transition. This fact supports an intuitive mechanism of beta-decay. However, other low-lying GT strengths contributing beta-decay are consisted of many configurations. We also discuss that the T=0 pairing plays an important role in the collectivity of the low-lying GT strength.

Event date： 2010.3

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

$eta$-decay half-lives around $^{78}$Ni and $^{132}$Sn in a self-consistent approach
$eta$-decay half-lives have been investigated within a random-phase approximation (pnQRPA). The strength that contributes to the $eta$-decay mainly comes from a small low-energy tail of the Gamow-Teller (GT) distribution, which is in general difficult to reproduce accurately with the pnQRPA. However, the pnQRPA approach has successfully reproduced the $eta$-decay half-lives by appropriately adjusting the proton-neutron pairing strength. In spite of the successful reproduction of $eta$-decay half-lives, those of $^{78}$Ni and $^{132}$Sn nuclei, in which the pairing correlation is not active, cannot be still reproduced reasonably. It might cause unacceptable predictions of beta-decay half-lives of neutron-rich nuclei. In order to investigate the difference between theoretical $eta$ half-lives of $^{78}$Ni and $^{132}$Sn and experimental one, we discuss the single particle levels and the GT distributions of them with the pnQRPA.

Event date： 2010.3

Language：Japanese  

Venue：岡山   Country：Japan  

Microscopic nuclear level densities with the Skyrme-Hartree-Fock method

Event date： 2010.3

Language：English  

Country：Japan  

$eta$-decay half-lives at finite temperatures with the Skyrme-QRPA
Using the finite-temperature quasiparticle random phase approximation (FTQRPA) on the basis of the finite temperature Skyrme-Hartree-Fock+Bardeen-Cooper-Schrieffer (BCS) method, we study $eta$-decay half-lives for even-even nuclei in a finite-temperature environment. We find that the $eta$-decay half-life first decreases as the temperature increases for all the nuclei we study, although the thermal effect is found to be small at temperatures relevant to r-process nucleosynthesis. Our calculations indicate that the half-life begins to increase at high temperatures for open-shell nuclei. We discuss this behavior in connection to the pairing phase transition.

Event date： 2009.10

Language：English   Presentation type：Oral presentation (general)  

Country：Other  

Fission of heavy $Lambda$ hypernuclei with the Skyrme-Hartree-Fock approach
It has been shown that the shape of a few deformed nuclei change toward spherical when a $Lambda$ particle is added to them. This is caused because the interaction between a $Lambda$ particle and a nucleon is attractive. This fact has motivated us to investigate the influence of $Lambda$ particle on the fission of heavy nuclei. We will discuss the fission-related phenomena of heavy $Lambda$ hypernuclei with the constraint Skyrme-Hartree-Fock+BCS (SHF+BCS) method. We employ a Skyrme-type interaction for the $Lambda N$ interaction and assume adiabaticity, that is, the $Lambda$ particle is assumed to be in the lowest state at all deformations. Our result confirms that the $Lambda$ particle is stuck to the heavier fission fragment, which is consistent with the experimental result of CERN. We will also discuss the deformation of heavy $Lambda$ hypernuclei and the $Lambda$ particle motion inside the core nuclei.

Event date： 2009.10

Language：English  

Venue：Waikoloa  

It has been shown that the shape of a few deformed nuclei change toward spherical when a $\Lambda$ particle is added to them. This is caused because the interaction between a $\Lambda$ particle and a nucleon is attractive. This fact has motivated us to investigate the influence of $\Lambda$ particle on the fission of heavy nuclei. We will discuss the fission-related phenomena of heavy $\Lambda$ hypernuclei with the constraint Skyrme-Hartree-Fock+BCS (SHF+BCS) method. We employ a Skyrme-type interaction for the $\Lambda N$ interaction and assume adiabaticity, that is, the $\Lambda$ particle is assumed to be in the lowest state at all deformations. Our result confirms that the $\Lambda$ particle is stuck to the heavier fission fragment, which is consistent with the experimental result of CERN. We will also discuss the deformation of heavy $\Lambda$ hypernuclei and the $\Lambda$ particle motion inside the core nuclei.

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Event date： 2009.9

Language：Japanese  

Venue：仙台   Country：Japan  

Effect of deformation dependence of the pairing correlation on nuclear level densities

Presentation type：Poster presentation  

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Language：Japanese   Publishing type：Internal/External technical report, pre-print, etc.  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Nuclear Chart - Magnificent landscape of nuclei

Language：Japanese   Publishing type：Internal/External technical report, pre-print, etc.  

Language：Japanese   Publishing type：Internal/External technical report, pre-print, etc.  

Language：English  

Activation cross-section file for decommissioning of LWRs
It is required to estimate radioactive products accurately for the decommissioning of LWRs. We have developed the neutron-induced activation cross-section file for this purpose. The products consist of 227 nuclides with half-lives larger than 30 days and 12 nuclides with very long half-lives. Target nuclei were selected by considering possible paths leading to the required products. The activation cross sections of these targets were taken from JENDL-4.0, JENDL/A-96 and the post JENDL-4.0 evaluations. As a result, we produced the activation cross-section file with 302 nuclides. Comparing with other evaluations, there exists a large difference especially for the capture cross sections leading to meta-stable states. The data will be released in FY2016 after achieving further improvements.

DOI： 10.11484/jaea-conf-2016-004

Language：English  

JENDL decay data file 2015
JENDL Decay Data File 2015 (JENDL/DDF-2015) has been produced. The decay data of nuclides with mass numbers from 1 to 260 are included. The nuclides with unknown $gamma$- and/or beta-emission are also included in order to keep decay chains. The data of 1,284 fission product nuclides with mass from 66 to 172 remain unchanged from JENDL/FPD-2011 except several corrections which had been claimed by users, and those of the newly added 1,953 nuclides are taken from ENSDF. Finally, the decay data of 3,237 nuclides including 244 stable nuclides were compiled as JENDL/DDF-2015 file.

DOI： 10.11484/jaea-data-code-2015-030

Language：English  

Compilation for chart of the nuclides 2014; A Comprehensive decay data
A chart of the nuclides 2014 version is now preparing to be published from JAEA. This will be the latest successive version of the chart since 1977, and continues every (approximately) four years until 2010. These charts include decay data of isotopes as half-lives, decay modes, and some isomeric states. In addition, the periodic table of elements, fundamental physical constants, thermal neutron capture and fission cross sections are tabulated. The latest version is now compiled with recent experimental data until the end of June in 2014. In the compilation process, we improved in the following parts: (1) Neutron or proton-unbound nuclei in the lighter region. (2) Drawing the neutron and proton-drip lines, and a boundary line of $eta$-delayed neutron emission. (3) 1- or 2-proton-emission theoretical half-lives are added for unmeasured nuclei in addition to original three partial half-lives of $alpha$-decay, $eta$-decay and spontaneous fission. We compiled totally 3150 nuclides, which were experimental identified including 2914 life-measured nuclei. We will show overview of the chart with some statistics and examples.

DOI： 10.11484/jaea-conf-2015-003

Language：Japanese  

Improvement of WWW chart of the nuclides interface
The booklet "chart of the nuclides" is issued every 4 years since 1976 from Nuclear Data Center, JAEA. The chart of the nuclides for WWW (World Wide Web) was developed in 1999 in order to be available from internet browser. Internet connection speeds, browser functions and JavaScript libraries has, however, progressed at present compared with the internet technology in those days. In connection with the release of the 2014 edition of the chart of the nuclides, the interface of the WWW chart of the nuclides has been improved by introducing new internet technologies aiming at enhancing convenience on accessibilities via browsers. We introduced a scrolling screen that would make capabilities of easy screen movement on a map with the addition of the drag scrolling function. Considering smart phone access, the light-weight edition which introduced automatic switch was prepared. The new system results in reduction in access time and usefulness in mobile environment. The method of making figures of the chart was reconsidered due to addition of new decay schemes to the 2014 edition. SVG (Scalable Vector Graphics) was adopted so as to make figures easily. It is concluded that the accessibilities of WWW chart of the nuclides are substantially improved from the previous version by introducing the new technologies.

DOI： 10.11484/jaea-data-code-2015-029

Language：Japanese   Publishing type：Internal/External technical report, pre-print, etc.  

Language：English  

Chart of the Nuclides 2014 (Press release)

Language：Japanese   Publishing type：Internal/External technical report, pre-print, etc.  

Language：English   Publishing type：Internal/External technical report, pre-print, etc.  

Novel concept of nuclear transmutation
Novel method of nuclear transmutation, which utilizes production of $Lambda$-hypernuclei of actinides, will be presented. It may give rise to a new nuclear transmutation mode in which long-lived fission products originating from the heavy fission fragments are not produced at all due to decay of $Lambda$ particle in the heavy fragment.