Present status of an R-matrix analysis code AMUR for cross-section evaluation in resolved resonance region

Kunieda, Satoshi

EPJ Web of Conferences, 284, p.03014_1 - 03014_4, 2023/05

https://doi.org/10.1051/epjconf/202328403014

For thorough understanding resonant theories and cause of discrepancies among different cross-section measurements, development of an R-matrix analysis code AMUR is being progressed. The code is organized by "theoretical" and "experimental" classes based on the object-oriented framework. In the theoretical class, with sharing the same compound nucleus, the independent distant poles can optionally be assumed for the simultaneous analysis of different projectile + nucleus pairs to see the relation between the channel radius and the theoretical background. In the experimental class, to simulate experimental conditions, calculated cross-sections can be corrected by the Doppler broadening, resolution functions, re-normalization, adding contaminant elements. I demonstrate some example analyses of measured cross-sections with AMUR both for the light and heavier nuclei to show effects of those new options. Also, preliminary results will be shown from analyses for experimental data of J-PARC/ANNRI.

Updates to the AMUR code for R-matrix analyses on heavy nuclei

Kunieda, Satoshi; Endo, Shunsuke; Kimura, Atsushi

EPJ Web of Conferences, 281, p.00017_1 - 00017_6, 2023/03

https://doi.org/10.1051/epjconf/202328100017

The AMUR code, which is based on the multi-channel/multi-level R-matrix theory, is under development for the cross-section evaluation with the covariance data in the resolved resonance energy region. Although, the code was initially designed for the analysis of the light-nuclei, the authors extended its capability toward the analysis of heavier nuclei by introducing the Reich-Moore approximation and the free-gas approximation for the Doppler broadening. In this work, we challenge a resonance analysis of neutron cross-section data measured in J-PARC/ANNRI with AMUR, in which the resolution functions and the double-bunching effects were taken into account inside the code. In this presentation, let us show results of resonance analysis on some of the J-PARC/ANNRI measurements together with covariance of the resonance parameters and cross-sections, for the first time. We also plan to discuss differences of correlation matrices among approximations of the R-matrix theory to understand physics underlying on the resonant reaction.

Collaboration with Dr. Efrem Sh. Soukhovitsukii; Our fortuitous experiences on optical model analysis, his contribution to nuclear data activities of Japan and a posthumous study on light-nuclei

Kunieda, Satoshi; Iwamoto, Osamu; Fukahori, Tokio; Chiba, Satoshi*

European Physical Journal A, 59(1), p.2_1 - 2_8, 2023/01

https://doi.org/10.1140/epja/s10050-022-00907-3

Optical model or coupled-channels calculation serves as an entrance to sophisticated calculation of nuclear data. It was a great contribution of Dr. Efrem Sh. Soukhovitsukii who has developed an excellent computation scheme which takes account of the low-lying collective nuclear structure in terms of the soft-rotator + vibrational model, and integrated it into the coupled-channels calculation. In Japan, we had a fortuitous experience with him in parametrization of the optical model potential (OMP) and to employ this methodology in nuclear data evaluation for JENDL. Firstly, we summarize our collaborative works with him in this paper. Secondly, let us have a discussion on a new parameterization of OMP which we obtained for light nuclei within his framework, quite recently. It was found that values of the potential parameters themselves are rather similar among different nuclei while the nuclear deformation describes one of the main characteristics of each isotopes.

Japanese Evaluated Nuclear Data Library version 5; JENDL-5

Iwamoto, Osamu; Iwamoto, Nobuyuki; Kunieda, Satoshi; Minato, Futoshi; Nakayama, Shinsuke; Abe, Yutaka*; Tsubakihara, Kosuke*; Okumura, Shin*; Ishizuka, Chikako*; Yoshida, Tadashi*; et al.

Journal of Nuclear Science and Technology, 60(1), p.1 - 60, 2023/01

https://doi.org/10.1080/00223131.2022.2141903

Reduction and resource recycling of high-level liquid radioactive waste through nuclear transmutation, 4; ImPACT/LLFP-2018: A New nuclear data library for a challenge on transmutation of long-lived fission products

Kunieda, Satoshi; Furutachi, Naoya*; Minato, Futoshi; Iwamoto, Nobuyuki; Iwamoto, Osamu

NEA/NSC/R(2020)4 (Internet), p.329 - 331, 2022/10

A new nuclear data library, ImPACT/LLFP-2018, is developed for an innovative study on the transmutation of long-lived fission products. In this work, we estimated cross-sections based on a nuclear model code CCONE, reflecting new knowledge on the nuclear structure theory and cross-section measurement. For instance, we used microscopic nuclear model to improve a phenomenological level density model. The pre-equilibrium model parameters are also optimized based on new experimental data of RIKEN/RIBF. Present library stores neutron and proton-induced cross-sections up to 200 MeV for 160 stable/unstable nuclei covering the long-lived fission products such as Se, Zr, Pd and Cs. Through a comparison with available experimental data on the stable isotopes, it is found that the present data gives predictions of cross-sections better than those from JENDL-4.0/HE, TENDL-2017 and the INCL model.

G-HyND: A Hybrid nuclear data estimator with Gaussian processes

Iwamoto, Hiroki; Iwamoto, Osamu; Kunieda, Satoshi

Journal of Nuclear Science and Technology, 59(3), p.334 - 344, 2022/03

https://doi.org/10.1080/00223131.2021.1971120

A hybrid nuclear data estimator (G-HyND) based on a machine learning technique with Gaussian processes (GP) was developed. G-HyND estimates cross-sections from a hybrid training dataset composed of an experimental dataset and an analytical dataset based on a nuclear physics model, and generates the cross-section datasets including the dataset's uncertainty information. It was demonstrated that an experimental dataset and a physics model-based analytical dataset perform a complementary role in nuclear data generation, and that the generated nuclear data from the hybrid training dataset are more reasonable than only those from the experimental dataset. Furthermore, solutions for two inherent GP problems, i.e., overfitting and computational cost, are presented within the G-HyND framework.

JENDL/ImPACT-2018; A New nuclear data library for innovative studies on transmutation of long-lived fission products

Kunieda, Satoshi; Furutachi, Naoya; Minato, Futoshi; Iwamoto, Nobuyuki; Iwamoto, Osamu; Nakayama, Shinsuke; Ebata, Shuichiro*; Yoshida, Toru*; Nishihara, Kenji; Watanabe, Yukinobu*; et al.

Journal of Nuclear Science and Technology, 56(12), p.1073 - 1091, 2019/12

https://doi.org/10.1080/00223131.2019.1647889

A new nuclear data library, JENDL/ImPACT-2018, is developed for an innovative study on the transmutation of long-lived fission products. Nuclear reaction cross- sections are newly evaluated for incident neutrons and protons up to 200 MeV for 163 nuclides including long-lived nuclei such as Se, Zr, Pd and Cs. Our challenge is an evaluation of cross-sections for a number of unstable nuclei over a wide energy range where the experimental data are very scarce. We estimated cross- sections based on a nuclear model code CCONE that incorporates an advanced knowledge on the nuclear structure theory and a model-parameterization based on a 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 predictions of cross-sections better than those in the existing libraries.

Verification of R-matrix calculations for charged-particle reactions in the resolved resonance region for the Be system

Thompson, I. J.*; deBoer, R. J.*; Dimitriou, P.*; Kunieda, Satoshi; Pigni, M. T.*; Arbanas, G.*; Leeb, H.*; Srdinko, Th.*; Hale, G.*; Tamagno, P.*; et al.

European Physical Journal A, 55(6), p.92_1 - 92_16, 2019/06

https://doi.org/10.1140/epja/i2019-12753-y

In this paper we present, for the first time, the results of a comprehensive effort to verify the most widely used R-matrix codes in the various fields of nuclear science and applications: AMUR, AZURE2, CONRAD, EDA, FRESCO, GECCCOS, and SAMMY. In addition to the description of the capabilities of the codes and their specifications, we discuss the results of a joint exercise which was coordinated by the International Atomic Energy Agency. The aim of the exercise was to compare calculations of charged-particle reaction cross sections for the light composite system Be. The calculations were performed by the codes using identical input R-matrix parameters and other specifications and were limited to charged-particle channels.

Nuclear data processing code FRENDY version 1

Tada, Kenichi; Kunieda, Satoshi; Nagaya, Yasunobu

JAEA-Data/Code 2018-014, 106 Pages, 2019/01

JAEA-Data-Code-2018-014.pdf:1.76MB
JAEA-Data-Code-2018-014-appendix(DVD-ROM).zip:6.99MB

A new nuclear data processing code FRENDY has been developed in order to process the evaluated nuclear data library JENDL. Development of FRENDY helps to disseminate JENDL and various nuclear calculation codes. FRENDY is developed not only to process the evaluated nuclear data file but also to implement the FRENDY functions to other calculation codes. Users can easily use many functions e.g., read, write, and process the evaluated nuclear data file, in their own codes when they implement the classes of FRENDY to their codes. FRENDY is coded with considering maintainability, modularity, portability and flexibility. The processing method of FRENDY is similar to that of NJOY. The current version of FRENDY treats the ENDF-6 format and generates the ACE file which is used for the continuous energy Monte Carlo codes such as PHITS and MCNP. This report describes the nuclear data processing methods and input instructions for FRENDY.

Joint Session of Nuclear Data Subcommittee and Sigma Special Advisory Committee; Present status and future of nuclear data evaluation code in Japan, 1; Development of AMUR for the evaluation of resonant cross-sections

Kunieda, Satoshi

Kaku Deta Nyusu (Internet), (120), p.3 - 10, 2018/06

A resonance analysis code AMUR is now under development for the nuclear data evaluation. This paper summarizes features of the R-matrix resonant theory, status of the code development and future plans for the experimental corrections. Furthermore, example analyses are shown for neutron cross-sections on O and F.