The angular distribution of individual γ rays, emitted from a neutron-induced compound-nuclear state via radiative capture reaction of La139(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 (Acosθγ+B), where θγ is the 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 use the result to quantify the possible enhancement of the breaking of time-reversal invariance in the vicinity of the p-wave resonance.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics