Detection of Neutron Sources in Cargo Containers

TL;DR

This paper explores a method for detecting hidden neutron sources in cargo containers using external semiconductor detectors, considering shielding effects and environmental neutron fluxes to improve security against nuclear threats.

Contribution

It introduces a practical detection approach with semiconductor photodiodes on container exteriors, accounting for shielding and environmental factors, enhancing cargo security measures.

Findings

Detectors can reliably identify unshielded neutron sources during ocean voyages.

Shielding with neutron-absorbing materials can significantly reduce detection sensitivity.

Surrounding sources with neutron-reflective material affects detection capabilities.

Abstract

We investigate the problem of detecting the presence of clandestine neutron sources, such as would be produced by nuclear weapons containing plutonium, within cargo containers. Small, simple and economical semiconductor photodiode detectors affixed to the outsides of containers are capable of producing statistically robust detections of unshielded sources when their output is integrated over the durations of ocean voyages. It is possible to shield such sources with thick layers of neutron-absorbing material, and to minimize the effects of such absorbers on ambient or artificial external neutron fluxes by surrounding them with neutron-reflective material.