Measurement of keV-neutron capture cross sections and capture gamma-ray spectra of Cs-133 and I-127

Laboratory for Advanced Nuclear Energy, Tokyo Institute of Technology, Japan

^a e-mail: umezawa.s.aa@m.titech.ac.jp

Published online: 13 September 2017

Abstract

The neutron capture cross sections and the capture gamma-ray spectra of ¹²⁷I and ¹³³Cs at incident neutron energies from 15 to 100 keV have been measured by the time-of-flight method. Capture gamma-rays were detected with an anti-Compton NaI(Tl) spectrometer, and the pulse-height weighting technique was applied to derive capture yields. The capture cross sections of ¹²⁷I and ¹³³Cs were determined using the standard capture cross section of ¹⁹⁷Au. The total errors of the cross sections were 3.8-5.1%. The obtained cross sections were compared with evaluated values in JENDL-4.0 and ENDF/B-VII.1. For ¹²⁷I, the energy dependence is different between the present results and the evaluations. For ¹³³Cs, the evaluated values in JENDL-4.0 agree with the present results but the evaluated values in ENDF/B-VII.1 are smaller than the present results by 14%–18%. The capture gamma-ray spectra of ¹³³Cs and ¹²⁷I were derived by unfolding the pulse height spectra with detector response functions.