Angular Distribution of γ-rays from Neutron-Induced Compound States of 140La

T. Okudaira, S. Takada, K. Hirota, A. Kimura, M. Kitaguchi, J. Koga, K. Nagamoto, T. Nakao, A. Okada, K. Sakai, H. M. Shimizu, T. Yamamoto, T. Yoshioka

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Angular distribution of individual γ-rays, emitted from a neutron-induced compound nuclear state via radiative capture reaction of 139La(n,γ) has been studied as a function of incident neutron energy in the epithermal region by using germanium detectors. An asymmetry ALH was defined as (NL − NH)/(NL + NH), where NL and NH are integrals of low and high energy region of a neutron resonance respectively, and we found that ALH has the angular dependence of (A cos θγ + B), where θγ is emitted angle of γ-rays, with A = −0.3881 ± 0.0236 and B = −0.0747 ± 0.0105 in 0.74 eV p-wave resonance. This angular distribution was analyzed within the framework of interference between s- and p-wave amplitudes in the entrance channel to the compound nuclear state, and it is interpreted as the value of the partial p-wave neutron width corresponding to the total angular momentum of the incident neutron combined with the weak matrix element, in the context of the mechanism of enhanced parity-violating effects. Additionally we used the result to quantify the possible enhancement of the breaking of the time-reversal invariance in the vicinity of the p-wave resonance.

Original languageEnglish
JournalUnknown Journal
Publication statusPublished - Oct 9 2017

All Science Journal Classification (ASJC) codes

  • General

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