Angular distribution of $\gamma$-rays from a neutron-induced $p$-wave resonance of $^{132}$Xe

TL;DR

This study measures the neutron-energy dependent angular distribution of gamma rays from a specific resonance in xenon, revealing enhanced parity violation due to s- and p-wave mixing, aiding understanding of fundamental symmetry violations.

Contribution

It provides the first detailed measurement of gamma-ray angular distributions from a neutron-induced p-wave resonance in xenon, highlighting parity violation effects.

Findings

Observed angular distribution varies with neutron energy.

Identified gamma-ray transitions to excited states of xenon.

Results support interference between s- and p-wave amplitudes as the cause.

Abstract

A neutron-energy dependent angular distribution was measured for individual $\gamma$-rays from the 3.2 eV $p$-wave resonance of $^{131}$Xe+$n$, that shows enhanced parity violation owing to a mixing between $s$- and $p$-wave amplitudes. The $\gamma$-ray transitions from the $p$-wave resonance were identified, and the angular distribution with respect to the neutron momentum was evaluated as a function of the neutron energy for 7132 keV $\gamma$-rays, which correspond to a transition to the 1807 keV excited state of $^{132}$Xe. The angular distribution is considered to originate from the interference between $s$- and $p$-wave amplitudes, and will provide a basis for a quantitative understanding of the enhancement mechanism of the fundamental parity violation in compound nuclei.