Upper Bounds on Parity Violating Gamma-Ray Asymmetries in Compound Nuclei from Polarized Cold Neutron Capture

Abstract

Parity-odd asymmetries in the electromagnetic decays of compound nuclei can sometimes be amplified above values expected from simple dimensional estimates by the complexity of compound nuclear states. In this work we use a statistical approach to estimate the root mean square (RMS) of the distribution of expected parity-odd correlations $\overrightarrow{s_n}\cdot \overrightarrow{k_{\gamma }}$, where $\overrightarrow{s_n}$ is the neutron spin and $\overrightarrow{k_{\gamma }}$ is the momentum of the gamma, in the integrated gamma spectrum from the capture of cold polarized neutrons on Al, Cu, and In and we present measurements of the asymmetries in these and other nuclei. Based on our calculations, large enhancements of asymmetries were not predicted for the studied nuclei and the statistical estimates are consistent with our measured upper bounds on the asymmetries.

22 pages, 6 figures

Cited by in corpus (4)

• Neutron Beam Effects on Spin Exchange Polarized He-3
• First Use of a Polarized ${}^3$He Neutron Spin Filter on the Back-n White Neutron Source of CSNS
• Measurement of the Parity-Odd Angular Distribution of Gamma Rays From Polarized Neutron Capture on ${}^{35}$Cl
• Monte Carlo calculation of the average neutron depolarization for the NPDGamma experiment