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

Kaplansky conjectured that if two positive-definite ternary quadratic forms have perfectly identical representations over ℤ, they are equivalent over ℤ or constant multiples of regular forms, or is included in either of two families parameterized by ℝ2. Our results aim to clarify the limitations imposed to such a pair by computational and theoretical approaches. First, the result of an exhaustive search for such pairs of integral quadratic forms is presented in order to provide a concrete version of the Kaplansky conjecture. The obtained list contains a small number of non-regular forms that were confirmed to have the identical representations up to 3,000,000 by computation. However, a strong limitation on the existence of such pairs is still observed, regardless of whether the coefficient field is ℚ or ℝ. Second, we prove that if two pairs of ternary quadratic forms have the identical simultaneous representations over ℚ, their constant multiples are equivalent over ℚ. This was motivated by the question why the other families were not detected in the search. In the proof, the parametrization of quartic rings and their resolvent rings by Bhargava is used to discuss pairs of ternary quadratic forms.

DOI： 10.1142/S1793042120500785

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

Determination of magnetic structure is an important analytical procedure utilized in various fields ranging from fundamental condensed-matter physics and chemistry to advanced manufacturing. It is typically performed using a neutron diffraction technique; however, finding global solutions of the magnetic structure optimization problem represents a significant challenge. Generally, it is not possible to mathematically prove that the obtained magnetic structure is a truly global solution and that no solution exists when no acceptable structure is found. In this study, the global optimization technique called semidefinite relaxation of quadratic optimization, which has attracted much interest in the field of applied mathematics, is proposed to use as a new analytical method for the determination of magnetic structure, followed by the application of polarized neutron diffraction data. This mathematical approach allows avoiding spurious local solutions, decreasing the amount of time required to find a tentative solution and finding multiple solutions when they exist.

DOI： 10.1038/s41598-018-34443-2

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

Maximum Entropy Method (MEM) is one of powerful tools for material science. We developed the program Z-MEM for evaluation of electron and nuclear density distribution by MEM analysis and Fourier synthesis. This code is designed by the multi-threading library OpenMP, so that the calculation performance is significantly improvements for MEM analysis. Z-MEM is bundled in Z-Rietveld, which is Rietveld software for X-ray and neutron powder diffraction, via the application programming interface (API). Since Z-MEM have equipped with the graphical user interface operations, users can perform from Rietveld refinement to MEM analysis seamlessly.

DOI： 10.1016/j.physb.2018.03.034

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

Computational methods and a program to obtain crystal structures that have the perfectly identical diffraction patterns, i.e. structure factors with the same absolute values and the same lattice symmetry are discussed. This is directly related to the uniqueness of solutions in crystal structure determination of single-crystal/powder-crystal samples from diffraction data. In order to solve the problem, it is necessary to solve a system of quadratic equations. The framework of positive-semidefinite programming is used herein to solve the system efficiently.

DOI： 10.1017/S0885715616000804

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

The present status of powder indexing software CONOGRAPH as an integrated system with a graphical user interface is reported. The improvements to the peak search method and the other available functions are introduced. Computational results and times for CONOGRAPH are compared with those for ITO13, N-TREOR and DICVOL14 to clarify their differences.

DOI： 10.1107/S1600576717001145

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

Geometrical ambiguity means the cases in which more than one powder indexing solution exists. Using a new function implemented in the powder indexing software CONOGRAPH, unit cells that involve geometrical ambiguity are exhaustively searched. As a result, many unknown cases are obtained, although the number of such unit cells is still rather limited. It is also proven that the number of solutions in powder auto-indexing is not always unique, but generally finite.

DOI： 10.1107/S2053273315021725

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

DOI： 10.1107/S2053273315015065

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

© 2014 International Union of Crystallography. A new algorithm is reported that returns all the lattices with the same set of d spacings as that of a given lattice. The algorithm is useful for quickly checking lattice parameters obtained for a considered powder diffraction pattern and assessing the reliability of the results of powder indexing. The proposed algorithm was implemented as a new function in the powder indexing software Conograph (http://sourceforge.jp/projects/conograph/; http://research.kek.jp/people/rtomi/ConographGUI/web-page.html). Examples of real cases are reported to explain how the algorithm can be used.

DOI： 10.1107/S1600576714023620

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

A new powder auto-indexing method for the CONOGRAPH software [Oishi-Tomiyasu (2013). Acta Cryst. A69, 603-610] can carry out exhaustive powder auto-indexing in a short time, even if the q values of many peaks are used, with sufficient consideration given to their observational errors. This article explains that the use of many q values is essential to make powder auto-indexing robust against dominant zones and missing or false peaks in the input. Results from CONOGRAPH for 25 real diffraction patterns, including difficult cases, are presented. Owing to a sorting criterion for zones defined in the previous article, the computation times were reduced by a factor of between 18 and 250, and exhaustive powder auto-indexing was completed in 5 min at most. © 2014.

DOI： 10.1107/S1600576714000922

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

Super High Resolution Powder Diffractometer SuperHRPD [1] at J-PARC have suffered damage by the Great East Japan Earthquake on 11 March 2011. After temporarily restoration work, the general user program has been started since April 2012. Full-fledged restoration of the temporarily restored devices is being carried out in 2013. The absorber materials for two disk choppers were replaced to ¹⁰B4C which improved quality of incident spectrum. The new detector system of 8 mm diameter position sensitive detectors was developed, and the test experiments showed excellent results.

DOI： 10.1088/1742-6596/502/1/012052

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

This paper presents several general properties of systematic absences that are available before unit-cell parameters and the space group have been determined. The properties are given in the form of distribution rules of Miller indices corresponding to systematic absences on a topograph. A topograph is a graph whose edges are associated with a set of four lattice vectors satisfying Ito's equation 2(|l 1 *|2 + |l 2 *|2) = |l 1 * + l 2 *|2 + |l 1 *-l 2 *|2. It is possible to integrate global information about extinct reflections by using topographs. As an example of the application of these rules, a new powder auto-indexing algorithm is introduced, focusing on its theoretical aspects. © 2013 International Union of Crystallography Printed in Singapore - all rights reserved.

DOI： 10.1107/S0108767313021740

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

Two new figures of merit for powder indexing solutions are proposed: the reversed figure of merit M n Rev and the symmetric figure of merit M n Sym. These are naturally suggested by the theory underlying the de Wolff figure of merit M n. Nevertheless, M n Rev has characteristics opposite to those of M n with regard to sensitivity to impurity peaks and extinct reflections. M n Sym has intermediate properties between M n and M n Rev. Applications of the new figures of merit to powder indexing solutions and zero-point shift estimation are introduced. All of the figures of merit are available from the powder auto-indexing software Conograph (http://sourceforge.jp/projects/conograph/; http://research.kek.jp/people/rtomi/ ConographGUI/web-page.html). © 2013 International Union of Crystallography Printed in Singapore - all rights reserved.

DOI： 10.1107/S0021889813018773

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

A new Bravais-lattice determination algorithm is introduced herein. For error-stable Bravais-lattice determination, Andrews & Bernstein [Acta Cryst. (1988), A44, 1009-1018] proposed the use of operations to search for nearly Buerger-reduced cells. Although these operations play an essential role in their method, they increase the computation time, in particular when lattice parameters obtained in (powder) auto-indexing are supposed to contain large errors. The new algorithm requires only several permutation matrices in addition to the operations that are necessary when the lattice parameters have exact values. As a result, the computational efficiency of error-stable Bravais-lattice determination is improved considerably. Furthermore, the new method is proved to be error stable under a very general assumption. The detailed algorithms and the set of matrices sufficient for error-stable determination are presented. © 2012 International Union of Crystallography Printed in Singapore-all rights reserved.

DOI： 10.1107/S0108767312024579

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

Z-Rietveld is a program suite for Rietveld analysis and the Pawley method; it was developed for analyses of powder diffraction data in the Materials and Life Science Facility of the Japan Proton Accelerator Research Complex. Improvements have been made to the nonlinear least-squares algorithms of Z-Rietveld so that it can deal with singular matrices and intensity non-negativity constraints. Owing to these improvements, Z-Rietveld successfully executes the Pawley method without requiring any constraints on the integrated intensities, even in the case of severely or exactly overlapping peaks. In this paper, details of these improvements are presented and their advantages discussed. A new approach to estimate the number of independent reflections contained in a powder pattern is introduced, and the concept of good reflections proposed by Sivia [J. Appl. Cryst. (2000), 33, 1295-1301] is shown to be explained by the presence of intensity non-negativity constraints, not the intensity linear constraints. © 2012 International Union of Crystallography Printed in Singapore-all rights reserved.

DOI： 10.1107/S0021889812003998

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

Super High Resolution Powder Diffractometer, SuperHRPD, is located at about 100 m from a thin side of a decoupled poisoned moderator at the Materials and Life Science Experimental Facility in the Japan Proton Accelerator Research Complex. The first neutron was produced successfully from a spallation neutron source in J-PARC in the end of May of 2008, and SuperHRPD has achieved the world best resolution Δd/d = 0.035% in June using the existing Sirius
¹
) chamber. In the summer of 2009, a new SuperHRPD chamber was installed aiming at increasing the detector solid angle and expanding d-range / Q-range, with at most 1500 one-dimensional
³
He position-sensitive detectors of 1/2 inch in diameter. The on-beam commissioning of the new SuperHRPD was started in the autumn of 2009.

DOI： 10.1143/JPSJS.80SB.SB020

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

The purpose of this paper is to show that the reflex fields of a given CM-field K are equipped with a certain combinatorial structure that has not been exploited yet.The first theorem is on the abelian extension generated by the moduli and the b-torsion points of abelian varieties of CM-type, for any natural number b. It is a generalization of the result by Wei on the abelian extension obtained by the moduli and all the torsion points. The second theorem gives a character identity of the Artin L-function of a CM-field K and the reflex fields of K. The character identity pointed out by Shimura (1977) in [10] follows from this.The third theorem states that some Pfister form is isomorphic to the orthogonal sum of TrK*(Φ)/Q(a{topbar}a) defined on the reflex fields ⊕Φ∈ΛK*(Φ). This result suggests that the theory of complex multiplication on abelian varieties has a relationship with the multiplicative forms in higher dimension. For a video summary of this paper, please click here or visit http://www.youtube.com/watch?v=IIwksVYV5YE. © 2010 Elsevier Inc.

DOI： 10.1016/j.jnt.2010.03.021

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

A new indexing algorithm is proposed that searches solutions thoroughly and quickly. The algorithm is well established for poor quality data e.g. for data containing some false peaks, or for those cases that peak positions coincide with two or more different lattices. It has succeeded for any lattice symmetry by carrying out the thorough search in several minutes at most. A graph structure called topograph, first introduced by the mathematician Conway, plays an important role in our method. In this paper, we introduce the algorithm and give some preliminary results.

DOI： 10.1524/zksu.2009.0002

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

Ibaraki prefecture, the local government of the area for J-PARC site, was decided to build a versatile neutron diffractometer (IBARAKI Materials Design Diffractometer, iMATERIA) to promote an industrial application for neutron beam in J-PARC. iMATERIA is planned to be a high throughput diffractometer so that materials engineers and scientists can use it like the chemical analytical instruments in their materials development process. It covers in d range 0.18<d (Å)<5 with Δd/d=0.16% at high resolution bank, and covers 5<d (Å)<800 with gradually changing resolution at three detector bank (90°, low angle and small angle). Typical measuring time to obtain a 'Rietveld-quality' data is several minutes with the sample size of laboratory X-ray diffractometer. To promote industrial application, a utilization system for this diffractometer is required. We will establish a support system for both academic and industrial users who are willing to use neutron but have not been familiar with neutron diffraction. The analysis software is also very important for powder diffraction, we will also prepare a software package consisting of combination of several powder-diffraction software, structural databases and visualization. The construction of iMATERIA will be completed in the end of April 2008, as one of day-one instruments for J-PARC.

DOI： 10.1016/j.nima.2008.11.137

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

A new analysis software suite, Z-Code, is under development for powder diffraction data analyses in the Materials and Life Science Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC). This software suite comprises data processing, data analyses, graphical user interface and visualization software. As a part of Z-Code, a Rietveld analysis program for neutron (TOF and angle dispersive) and X-ray data, Z-Rietveld, has been developed. Here we report the basic traits and some significant features of Z-Rietveld.

DOI： 10.1016/j.nima.2008.11.056

Language：Japanese  

Language：Japanese  

Language：English  

Copyright © International Centre for Diffraction Data 2017. Computational methods and a program to obtain crystal structures that have the perfectly identical diffraction patterns, i.e. structure factors with the same absolute values and the same lattice symmetry are discussed. This is directly related to the uniqueness of solutions in crystal structure determination of single-crystal/powder-crystal samples from diffraction data. In order to solve the problem, it is necessary to solve a system of quadratic equations. The framework of positive-semidefinite programming is used herein to solve the system efficiently.

DOI： 10.1017/S0885715616000804

Language：Japanese  

粉末指数付けソフトウェアCONOGRAPH

DOI： 10.5940/jcrsj.57.129

Language：Others  

Development of an Advanced Special Neutron Powder Diffractometer under Extreme Environment for Materials

Language：Japanese  

27pXZB-1 Structure Analysis and Direction of Polarization of STO18 using SHRPD at J-PARC

Language：Japanese  

汎用中性子回折装置,茨城県材料構造解析装置(iMATERIA)の現状について(III)

Language：English  

Super High Resolution Powder Diffractometer, SuperHRPD, is located at about 100 m from a thin side of a decoupled poisoned moderator at the Materials and Life Science Experimental Facility in the Japan Proton Accelerator Research Complex. The first neutron was produced successfully from a spallation neutron source in J-PARC in the end of May of 2008, and SuperHRPD has achieved the world best resolution Δd/d = 0.035&#37; in June using the existing Sirius 1) chamber. In the summer of 2009, a new SuperHRPD chamber was installed aiming at increasing the detector solid angle and expanding d-range / Q-range, with at most 1500 one-dimensional 3He position-sensitive detectors of 1/2 inch in diameter. The on-beam commissioning of the new SuperHRPD was started in the autumn of 2009. © 2011 The Physical Society of Japan.

DOI： 10.1143/JPSJS.80SB.SB020

Language：English  

A new analysis software suite, Z-Code, is under development for powder diffraction data analyses in the Materials and Life Science Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC). This software suite comprises data processing, data analyses, graphical user interface and visualization software. As a part of Z-Code, a Rietveld analysis program for neutron (TOF and angle dispersive) and X-ray data, Z-Rietveld, has been developed. Here we report the basic traits and some significant features of Z-Rietveld. © 2008.

DOI： 10.1016/j.nima.2008.11.056

Language：English  

Ibaraki prefecture, the local government of the area for J-PARC site, was decided to build a versatile neutron diffractometer (IBARAKI Materials Design Diffractometer, iMATERIA) to promote an industrial application for neutron beam in J-PARC. iMATERIA is planned to be a high throughput diffractometer so that materials engineers and scientists can use it like the chemical analytical instruments in their materials development process. It covers in d range 0.18<d (Å)<5 with Δd/d=0.16&#37; at high resolution bank, and covers 5<d (Å)<800 with gradually changing resolution at three detector bank (90°, low angle and small angle). Typical measuring time to obtain a 'Rietveld-quality' data is several minutes with the sample size of laboratory X-ray diffractometer. To promote industrial application, a utilization system for this diffractometer is required. We will establish a support system for both academic and industrial users who are willing to use neutron but have not been familiar with neutron diffraction. The analysis software is also very important for powder diffraction, we will also prepare a software package consisting of combination of several powder-diffraction software, structural databases and visualization. The construction of iMATERIA will be completed in the end of April 2008, as one of day-one instruments for J-PARC. © 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nima.2008.11.137

Language：Japanese  

Neutron Powder Diffractometers in J-PARC and Its Impact for Materials Science or Materials Developing
Here we describe two neutron powder diffractometers, iMATERIA and SHRPD, at the Materials and Life Science Experimental Facility in J-PARC. iMATERIA (IBARAKI Materials Design Diffractometer) has been constructed to be a high throughput versatile diffractometer enabling materials scientists to use it like a chemical analytical instrument in their material development processes. Typical measuring time to obtain &#039;Rietveld-quality&#039; data is several minutes for the sample size of laboratory X-ray diffractometer. On the other hand, SHRPD (Super High Resolution Powder Diffractometer) has been constructed by J-PARC to promote the best science using the best resolution in the world (Δd/d=0.03&#37;) . Two instruments will be ready by the Day-One.

DOI： 10.5940/jcrsj.50.18

Language：Japanese  

Neutron Powder Diffractometers in J-PARC and Its Impact for Materials Science or Materials Developing

DOI： 10.5940/jcrsj.50.18

Error-stable Bravais lattice determination

Other Link： https://github.com/rtomiyasu.html (old site: http://conograph.osdn.jp/InstructionsBLDConograph.html )

Work type：Software   Location：Journal of Applied Crystallography (2012)  

Moved from https://z-code.kek.jp/zrg/ in 2023.

DOI： 10.1107/S0021889812003998

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Work type：Software   Location：Journal of Applied Crystallography (2014)  

moved from https://z-code.kek.jp/zrg/ in 2023

DOI： 10.1107/S1600576714000922

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Other Link： https://github.com/rtomiyasu/

Work type：Software   Location：Journal of Applied Crytallography (2017)  

Moved from http://conograph.osdn.jp/InstructionsPeakSearch.html in 2023

DOI： 10.1107/S1600576717001145

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Work type：Software   Location：Acta Cryst. A (2012)  

Moved from http://conograph.osdn.jp/InstructionsBLDConograph.html in 2012.

DOI： 10.1107/S0108767312024579

researchmap