Tokio Fukahori

Particle and Heavy Ion Transport code System, PHITS, version 2.52

An upgraded version of the Particle and Heavy Ion Transport code System, PHITS2.52, was developed and released to the public. The new version has been greatly improved from the previously released version, PHITS2.24, in terms of not only the code itself but also the contents of its package, such as the attached data libraries. In the new version, a higher accuracy of simulation was achieved by implementing several latest nuclear reaction models. The reliability of the simulation was improved by modifying both the algorithms for the electron-, positron-, and photon-transport simulations and the procedure for calculating the statistical uncertainties of the tally results. Estimation of the time evolution of radioactivity became feasible by incorporating the activation calculation program DCHAIN-SP into the new package. The efficiency of the simulation was also improved as a result of the implementation of shared-memory parallelization and the optimization of several time-consuming algorithms. Furthermore, a number of new user-support tools and functions that help users to intuitively and effectively perform PHITS simulations were developed and incorporated. Due to these improvements, PHITS is now a more powerful tool for particle transport simulation applicable to various research and development fields, such as nuclear technology, accelerator design, medical physics, and cosmic-ray research.

Towards a More Complete and Accurate Experimental Nuclear Reaction Data Library (EXFOR). International Collaboration Between Nuclear Reaction Data Centres (NRDC)

The International Network of Nuclear Reaction Data Centres (NRDC) coordinated by the IAEA Nuclear Data Section (NDS) successfully collaborates in the maintenance and development of the EXFOR library. As the scope of published data expands (e.g. to higher energy, to heavier projectile) to meet the needs of research and applications, it has become a challenging task to maintain both the completeness and accuracy of the EXFOR library. Evolution of the library highlighting recent developments is described.

The nuclear interaction at Oklo 2 billion years ago

Abstract We re-examine the effort to constrain the time variability of the coupling constants of the fundamental interactions by studying the anomalous isotopic abundance of Sm observed at the remnants of the natural reactors which were in operation at Oklo about 2 billion years ago, in terms of a possible deviation of the resonance energy from the value observed today. We rely on new samples that were carefully collected to minimize natural contamination and also on a careful temperature estimate of the reactors. We obtain the upper bound (−0.2±0.8)×10 −17 y −1 on the fractional rate of change of the electromagnetic as well as the strong interaction coupling constants. Our result basically agrees with and even suggests some improvement of the result due recently to Damour and Dyson. Strictly speaking, however, we find another choice of the resonance energy shift indicating a non-zero time variation of the constants. However, we find a rather strong but still tentative indication that this non-null range can be ruled out by including Gd data, for which it is essential to take the effect of contamination into account.

Neutron-Induced Fission of 233U, 238U, 232Th, 239Pu, 237Np, natPb and 209Bi Relative to 235U in the Energy Range 1-200 MeV

Fission cross section ratios of 233U, 238U, 232Th, 239Pu, 237Np, natural Pb and 209Bi to 235U have been measured in a wide energy range of incident neutrons from 1 MeV to 200 MeV using a time-of-flight technique at the neutron spectrometer GNEIS based on the 1-GeV proton synchrocyclotron of PNPI. For actinide targets, the threshold cross section method and evaluated data below 14 MeV were used for normalization of the shape measurement data, while the evaluated and recommended fission cross sections of 235U were used to convert the ratio data to absolute fission cross sections. For Pb and Bi targets, an absolute normalization of the measured cross section ratios has been done using the thickness of the targets and detection efficiencies.

Nuclear Data Evaluations for JENDL High‐Energy File

An overview is presented of recent nuclear data evaluations performed for the JENDL high‐energy (JENDL‐HE) file, in which neutron and proton cross sections for energies up to 3 GeV are included for the whole 132 nuclides. The current version of the JENDL‐HE file consists of neutron total cross sections, nucleon elastic scattering cross sections and angular distributions, nonelastic cross sections, production cross sections and double‐differential cross sections of secondary light particles (n, p, d, t, 3He, α, and π) and gamma‐rays, isotope production cross sections, and fission cross sections in the ENDF6 format. The present evaluations are performed on the basis of experimental data and theoretical model calculations. For the cross section calculations, we have constructed a hybrid calculation code system with some available nuclear model codes and systematics‐based codes, such as ECIS96, OPTMAN, GNASH, JQMD, JAM, TOTELA, FISCAL, and so on. The evaluated cross sections are compared with available experimental data and the other evaluations. Future plans of our JENDL‐HE project are discussed along with prospective needs for high‐energy cross section data.An overview is presented of recent nuclear data evaluations performed for the JENDL high‐energy (JENDL‐HE) file, in which neutron and proton cross sections for energies up to 3 GeV are included for the whole 132 nuclides. The current version of the JENDL‐HE file consists of neutron total cross sections, nucleon elastic scattering cross sections and angular distributions, nonelastic cross sections, production cross sections and double‐differential cross sections of secondary light particles (n, p, d, t, 3He, α, and π) and gamma‐rays, isotope production cross sections, and fission cross sections in the ENDF6 format. The present evaluations are performed on the basis of experimental data and theoretical model calculations. For the cross section calculations, we have constructed a hybrid calculation code system with some available nuclear model codes and systematics‐based codes, such as ECIS96, OPTMAN, GNASH, JQMD, JAM, TOTELA, FISCAL, and so on. The evaluated cross sections are compared with available experi...

JENDL High Energy File

Nuclear Data Center at Japan Atomic Energy Research Institute is developing the JENDL High Energy File in cooperating with Japanese Nuclear Data Committee. The JENDL High Energy File includes neutron and proton nuclear data 20 MeV to 3 GeV. In this report, reported are evaluation methods and results of the evaluation and benchmark tests for the JENDL High Energy File.

Global coupled-channel optical potential for nucleon-actinide interaction from 1 keV to 200 MeV

A coupled-channel method was used for the estimation of nucleon optical potential parameters for the actinide region based on the axial rigid-rotor model built on a saturated coupling scheme. A new global form of optical potential was proposed to incorporate energy dependences guided by physical principles. Best-fit potential parameters were searched for to reproduce experimental nucleon scattering angular distributions, low-energy observables (strength functions and scattering radii) and neutron total cross sections of 238U and 232Th. It was found that the present form of the optical potential could reproduce both the neutron- and proton-data for a wide energy range, namely from 1 keV to 200 MeV. Available experimental data for other actinides were also described to a good accuracy with the same set of parameters only by adjusting the deformation parameters for each nucleus.

Measurement of activation cross-sections for (n,2n) reactions producing short-lived nuclei in the energy range between 13.4 and 14.9 MeV

Abstract Activation cross-sections for 18 (n,2n) reactions producing short-lived nuclei with half-lives between 20 s and 38 min were measured in the energy range between 13.4 and 14.9 MeV by an activation method. The measured target isotopes were 14N, 31P, 54Fe, 63Cu, 79Br, 87Rb, 92Mo, 108Pd, 113In, 132Ba, 138Ba, 140Ce, 141Pr, 144Sm and 165Ho. Four cross-sections for 108Pd, 132Ba, 144Sm and 165Ho were obtained at six-point energies for the first time. The intense 14 MeV neutron source facility (OKTAVIAN) at Osaka University was used for irradiation. All cross-section values were relatively obtained on the basis of the standard cross-section of 27Al(n, α) 24Na reaction (ENDF/B-VI). To obtain reliable neutron activation cross-sections, careful attention was paid to neutron irradiation and induced activities measurement. The present results were compared with previous data and the evaluated data in JENDL-3.2, JENDL-Activation File and ENDF/B-VI. The previous data measured at multi-point energies show reasonable agreement with the present results in comparison with those at one-point energy. There are overestimations of the cross-section for 31P in JENDL-3.2 and ENDF/B-VI, and for 132Ba and 165Ho in JENDL-Activation File.

Analysis of proton-induced fragment production cross sections by the quantum molecular dynamics plus statistical decay model

The production cross sections of various fragments from proton-induced reactions on {sup 56}Fe and {sup 27}Al have been analyzed by the quantum molecular dynamics (QMD) plus statistical decay model (SDM). It was found that the mass and charge distributions calculated with and without the statistical decay have very different shapes. These results also depend strongly on the impact parameter, showing an importance of the dynamical treatment as realized by the QMD approach. The calculated results were compared with experimental data in the energy region from 50 MeV to 5 GeV. The QMD+SDM calculation could reproduce the production cross sections of the light clusters and intermediate-mass to heavy fragments in a good accuracy. The production cross section of {sup 7}Be was, however, underpredicted by approximately 2 orders of magnitude, showing the necessity of another reaction mechanism not taken into account in the present model. {copyright} {ital 1996 The American Physical Society.}

JENDL Photonuclear Data File

JENDL Photonuclear Data File 2004 was released in March 2004 and contains the photonuclear data for 68 nuclides from 2H to 237Np. We were proceeding on the evaluation work with the help of theoretical calculations based on statistical nuclear reaction models. The photonuclear cross sections that are to be contained in the file are as follows: photoabsorption cross sections, yield cross sections, and double‐differential cross sections for photoneutrons, photoprotons, photodeuterons, phototritons, photo‐3He‐particles and photoalpha‐particles, and isotope production cross sections. For the actinide nuclides, physical quantities related to photofission reactions are also included. The maximum energy of incident photons is 140 MeV, which is the energy at which the pion production channel opens.