Satoshi Kunieda

JENDL-4.0 : A New Library for Nuclear Science and Engineering

The fourth version of the Japanese Evaluated Nuclear Data Library has been produced in cooperation with the Japanese Nuclear Data Committee. In the new library, much emphasis is placed on the improvements of fission product and minor actinoid data. Two nuclear model codes were developed in order to evaluate the cross sections of fission products and minor actinoids. Coupled-channel optical model parameters, which can be applied to wide mass and energy regions, were obtained for nuclear model calculations. Thermal cross sections of actinoids were carefully examined by considering experimental data or by the systematics of neighboring nuclei. Most of the fission cross sections were derived from experimental data. A simultaneous evaluation was performed for the fission cross sections of important uranium and plutonium isotopes above 10 keV. New evaluations were performed for the thirty fissionproduct nuclides that had not been contained in the previous library JENDL-3.3. The data for light elements and structural materials were partly reevaluated. Moreover, covariances were estimated mainly for actinoids. The new library was released as JENDL-4.0, and the data can be retrieved from the Web site of the JAEA Nuclear Data Center.

Coupled-channels optical model analyses of nucleon-induced reactions for medium and heavy nuclei in the energy region from 1 keV to 200 MeV

Optical model analyses were carried out using the coupled-channels method over various medium and heavy nuclei for incident neutrons and protons in the energy region from 1 keV to 200 MeV. Global systematics were consequently obtained for the optical potential parameters with simple functional forms. It was confirmed that coupled-channels analyses were indispensable to achieving a global description of experimental data for wide ranges of energies and mass numbers (50 ≤ A ≥ 240). It was also found that the parameter set obtained would be useful for nuclear data evaluations of fission-product nuclei for which available experimental data are scarce.

Development of SCINFUL-QMD Code to Calculate the Neutron Detection Efficiencies for Liquid Organic Scintillator up to 3 GeV

The Monte Carlo code, designeted SCINFUL-QMD, has been developed to calculate neutron detection efficiency up to 3 GeV for liquid organic scintillators such as NE-213. The existing Monte Carlo code, SCINFUL, is known to reproduce a response function and detection efficiency at incident neutron energies below 80 MeV. We incorporate the quantum molecular dynamics plus statistical decay model (QMD+SDM) into SCINFUL to extend the upper limit of incident neutron energy to 3 GeV. The results by SCINFUL-QMD are compared with experimental data and those of CECIL. The SCINFUL-QMD exhibits an increase in detection efficiency above 300 MeV. This tendency agrees with one of the experimental data. The increase is achived by taking charged pion production into account.

Calculation of Neutron Nuclear Data on Silicon Isotopes for JENDL-4

Neutron nuclear data on 92,94,95,96,97,98,99,100 Mo have been calculated for the evaluated nuclear data library JENDL-4. Simultaneously calculated are the total, elastic and inelastic scattering, (n, p), (n, d), (n, t), (n, 3He), (n, α), (n, np), (n, nd), (n; nα), (n, 2n), (n, 3n) reaction cross sections, the angular distributions of emitted particles, and the energy distributions of emitted particles and γrays. The statistical model was applied to calculate these quantities. Coupled-channel optical model parameters were used for neutrons. Preequilibrium and direct-reaction processes were taken into account in addition to the compound process. The present calculations are almost consistent with available experimental data. The calculated results are compiled into JENDL-4.

Parameterization of Proton-induced Neutron Production Double Differential Cross Section up to 3 GeV in Terms of Moving Source Model

The parameterization of double differential cross sections is made for the neutron emission from proton- induced spallation reaction. The emitted neutron data for incident proton energies of 0.8 to 3 GeV are analyzed by the three-component moving source model based on the Maxwell-like energy distribution. In addition, a Gaussian-shaped term is utilized for reproducing the neutron spectrum originating from the quasi-elastic- and quasi-inelastic-like scattering. The systematics of parameters is obtained in the target mass number region from C to Pb.

Calculation of Neutron Cross Sections on 93Nb for JENDL-4

Nuclear data of 93Nb in the Japanese Evaluated Nuclear Data Library JENDL-3.3 were reexamined in the incident neutron energy range from 10keV to 20MeV toward JENDL-4. Cross sections, differential and double-differential cross sections were calculated on the basis of nuclear reaction models such as the spherical optical model, the distorted wave Born approximation, the Kalbach preequilibrium model, and the Hauser-Feshbach statistical model. It was found that experimental neutron emission spectra were reproduced well by the present calculation compared with the JENDL-3.3 evaluations for emission energies > 1 MeV. Also, calculated cross sections were almost consistent with the available experimental data for total, elastic and inelastic scattering, (n, γ), (n, 3n), (n, Xp), (n, Xd), (n, t), (n, α), (n, nα), and (n, Xα) reactions. An appreciable change from the JENDL-3.3 evaluation was not seen for the (n,2n) cross section, which was about 20 percent larger than the experiments for incident energies ≤ 14 MeV.

Evaluation of Neutron Nuclear Data on Bromine and Krypton Isotopes for JENDL-4.0

Neutron nuclear data on 79,81Br and 78,80,82,83,84,85,86Kr have been evaluated for the evaluated nuclear data library JENDL-4.0 in the energy region from 10−5 eV to 20 MeV. The resolved resonance parameters were adjusted so as to reproduce recommended or measured thermal capture cross sections for some isotopes. The statistical model was applied to calculate the cross sections above the resolved resonance region. In the calculations, coupled-channel optical model parameters were used for neutrons. Preequilibrium and direct-reaction processes were taken into account in addition to the compound process. The present evaluation is consistent with available experimental data. The evaluated results were compiled into JENDL-4.0.

Calculation of Neutron Nuclear Data on Rubidium and Strontium Isotopes for JENDL-4

Neutron nuclear data on 85,86,87Rb and 84,86,87,88,89,90Sr have been calculated for the evaluated nuclear data library JENDL-4 in the energy region from 10 keV to 20MeV. Simultaneously calculated are the total, elastic, and inelastic scattering, (n,γ), (n, p), (n, d), (n, t), (n,3He), (n,α), (n, np), (n, nd), (n, nα), (n, 2n), (n, 3n) reaction cross sections, angular distributions of emitted particles, and energy distributions of emitted particles and γ-rays. The statistical model was applied to calculate these quantities. Coupledchannel optical model parameters were used for neutrons. Preequilibrium and direct-reaction processes were taken into account in addition to the compound process. The present calculations are consistent with available experimental data. The calculated results are compiled into JENDL-4.

Extensive Study of the Soft-Rotator Model Hamiltonian Parameters for Medium and Heavy Even-Even Nuclei

Soft-rotator model Hamiltonian parameters were deduced for 63 even-even nuclei in the mass range 56 ≤ A ≤ 238 by a combination of low-lying level structure and coupled-channel proton scattering analyses toward a systematic and accurate calculation of nuclear data. It was found that the obtained effective quadrupole and octupole deformation parameters were consistent with those derived from experimental B(E2) and B(E3) data. In addition, equilibrium ground-state quadrupole deformation parameters were also in reasonable accord with theoretical results for deformed heavy nuclei. The obtained parameters often varied with neutron and/or proton numbers anomalously, showing mostly the effects of shell closure. On the other hand, some clear systematic trends were seen among major Hamiltonian parameters.

Calculation of Neutron Cross Sections on 90;91;92;94;96Zr for JENDL-4

Neutron nuclear data of 90;91;92;94;96Zr were calculated for the development of the 4-th version of the Japanese Evaluated Nuclear Data Library (JENDL-4) in the incident neutron energy (En ) range above the resolved resonance region to 20 MeV by using nuclear reaction models, such as the spherical optical model, thedistorted wave Born approximation, the Kalbach preequilibrium model, and the Hauser-Feshbach statistical model. The obtained cross sections were almost consistent with the experimental data for elastic, nonelastic and inelastic scattering, (n;γ), (n,2n), (n, p), and (n,α). The agreement with recent experiments is better than the evaluated data in JENDL-3.3 for the (n,α) cross sections on 90,92,94Zr.