Two Neutron Correlation Study in Photofission of Actinides

TL;DR

This paper investigates the correlation of two neutrons emitted in actinide photofission, revealing a significant asymmetry in neutron emission directions, which could enhance detection techniques and understanding of neutron correlations.

Contribution

It introduces a novel approach to study two neutron correlations in actinide photofission, highlighting asymmetry effects and potential applications in security detection.

Findings

Large asymmetry in neutron emission directions observed

Neutron anti-parallel emission exceeds parallel emission

Energy cuts amplify the asymmetry effect

Abstract

It is well known that two fission fragments (FF's) are emitted essentially back to back in the laboratory frame. That can be used widely in many applications as a unique signature of fissionable materials. However, such fission fragments are difficult to detect. The energy and angular distributions of neutrons, on the other hand, are easy to measure, and that distribution will carry information about the fission fragment's energy and angular spectra, as well as the neutron spectra in the fission fragment rest frame. We propose to investigate the two neutron correlation yield resulting from two FF's as a function of different targets, the angle between the two neutrons and the neutron energies. The preliminary calculation of the two neutron correlation shows a huge asymmetry effect: many more neutrons are emitted anti-parallel to each other than parallel to each other. That asymmetry becomes even more if the energy cut on each neutron is done. This study will potentially permit a new technique for actinide detection for homeland security and safeguards applications as well as improve our knowledge of correlated neutron emission.