Generalization of the Maier-Leibniz Doppler-Shift Method for Gamma-Ray Correlations in Fission

TL;DR

This paper extends the Maier-Leibniz Doppler-Shift method to measure not only mean gamma-ray multiplicities from fission fragments but also their second moments and covariances, enhancing the analysis of fragment correlations.

Contribution

The work generalizes the Doppler-Shift technique to include second moments and covariance measurements of gamma-ray emissions in fission, providing new insights into fragment correlations.

Findings

The extended method can measure second moments of gamma-ray emissions.

It allows inference of covariance between fragments' gamma-ray emissions.

Experimental considerations and convergence are discussed.

Abstract

The Maier-Leibniz Doppler-Shift technique is the most popular and accurate technique used in fission experiments to separate the yield of gamma rays from each of the two fission fragments. The technique exploits the aberration, i.e., the change in the angular distribution, of gamma rays emitted by a moving source. By measuring the speed and direction of the source with a conventional detector, as well as the yield of gamma rays at several angles from the direction of motion, the technique can be used to determine the mean multiplicities of gamma rays from each fragment. We show in this work that it is possible to extend the technique to also measure second moments of the gamma ray radiation from each fragment. In particular, given the current interest in fragment correlations in fission, we show that the covariance of the emission between the two fragments can be inferred. Experimental limitations and convergence of the new technique are discussed.