Improvement of Gamma-ray Production Data for JENDL-3.2.

Abstract

Gamma-ray production cross sections and spectra have been updated for the latest version of JENDL-3 (JENDL-3.2). Problems of g-ray production data contained in the previous version JENDL-3.1 were examined, and they have been mostly resolved in the present work. In the medium-heavy mass region, capture g-ray spectra for incident neutron energies below 10keV were re-calculated with the statistical model taking account of experimentally determined branching ratios for primary transitions. For natural elements, line gamma rays due to inelastic scattering were explicitly given in JENDL-3.2 up to several MeV. Capture cross sections of some light nuclides were evaluated by considering a p-wave capture behavior indicated by recent measurements. Gamma-ray production data for 66 nuclides have been compiled into JENDL-3.2 in the ENDF-6 format.

JENDL: Nuclear databases for science and technology

“…To improve the inelastic scattering cross section of iron, the cross sections for the low-lying levels of 56 Fe were modified, and resonance structure was introduced to the cross section for the first level of 57 Fe. Concerning the DDXs, the MF6 data of JENDL/F-99 [57] were converted to the conventional MF4-MF5 representation, and the converted data were adopted for 19 F, 27 Al, nat, 28,29,30 Si, nat, 40,42,43,44,46,48 Ca, nat, 46,47,48,49,50 Ti, 51 V, nat, 50,52,53,54 Cr, 55 Mn, nat, 54,56,57, 58 Fe, 59 Co, nat, 58,60,61,62,64 Ni, nat, 63,65 Cu, 75 As, nat, 90,91,92,94,96 Zr, 93 Nb, nat, 92,94,95,96,97,98,100 Mo, nat, 121,…”

“…However, several drawbacks were found, i.e., inconsistency between inelastic scattering and cascade gamma-ray production cross sections, energy imbalance of capture reactions, and inconsistent thermal-energy gamma-ray spectra between isotopes and a natural element. These problems were solved [59] for JENDL-3.2. Moreover, p-wave capture, which is proportional to the velocity of an incident neutron, was considered for 3 He, 12 C, and 16 O.…”

“…The matrices represent not only the correlation of individual fission cross sections between different incident energies but also that of a fission cross section with another fission cross section, e.g., 235 U(n, f ) vs. 239 Pu(n, f ). The covariances for 48 T, nat V, and 59 Co were newly evaluated for JENDL-3.3.…”

“…As for structural materials, we revised the data on Si [78], Ca [79], Ti, Cr, Mn, Fe, Cu, and W. Moreover, new evaluations were performed for 50,51 V, 59 Fe, 59 Ni, and 180 W. Concerning vanadium, only the elemental data are contained in JENDL-3.3. For JENDL-4.0, the data on two isotopes 50,51 V were evaluated.…”

“…Covariances are given for 95 nuclides, i.e., 10,11 B, 14,15 N, 16 O, 23 Na, 48 Ti, 52,53 Cr, 55 Mn, 56 Fe, 59 Co, 58,60 Ni, 90 Zr, 209 Bi, and all actinoids. Except for the actinoids, most of the covariances were taken from JENDL-3.3 or an additional work [97].…”