EVALUATION OF NEUTRON CROSS SECTIONS FOR A COMPLETE SET OF Nd ISOTOPES.

Abstract

Neutron cross sections for a complete set of Nd isotopes, 142,143,144,145,146,147,148,150 Nd, were evaluated in the incident energy range from 10 −5 eV to 20 MeV. In the low energy region, including thermal and resolved resonances, our evaluations are based on the latest data published in the Atlas of Neutron Resonances. In the unresolved resonance region we performed additional evaluation by using the averages of the resolved resonances and adjusting them to the experimental data. In the fast neutron region, we used the nuclear reaction model code EMPIRE-2.19 validated against the experimental data. The results are compared to the existing nuclear data libraries, including ENDF/B-VI.8, JENDL-3.3 and JEFF-3.1, and to the available experimental data. The new evaluations are suitable for neutron transport calculations and they were adopted by the new evaluated nuclear data file of the United States, ENDF/B-VII.0, released in December 2006. 24.10.Eq, 24.60.Dr, 24.60.Gv, 25.40.Fq * Corresponding author.Email addresses: hikim@kaeri.re.kr (Hyeong Il Kim), mwherman@bnl.gov (M. Herman), mugabgab@bnl.gov (S. F. Mughabghab), oblozinsky@bnl.gov (P. Obložinský), rochman@nrg-nl.com, present address NRG, PO Box 25, 1755 ZG Petten, The Netherlands (D. Rochman), yolee@kaeri.re.kr (Young-Ouk Lee).

The joint evaluated fission and fusion nuclear data library, JEFF-3.3

“…The lower energy boundaries for these cross sections are at 3.0 eV, 1.1 eV and 3.1 eV for 240 Cm, 241 Cm and 249 Cm, respectively. Given the limited number of experimental data a procedure similar to the one applied for Nd-isotopes was followed [103]. This procedure relies on model parameters, such as the parameters of the optical model potential and the asymptotic value of the level density parameter, that vary smoothly as a function of mass number.…”