Comparison of Lithium Gadolinium Borate Crystal Shards in Scintillating and Nonscintillating Plastic Matrices

TL;DR

This paper compares neutron detection efficiency and gamma rejection of scintillating versus nonscintillating plastic matrices embedded with lithium gadolinium borate crystal shards, aiming to improve detector performance for practical applications.

Contribution

It introduces a method to embed crystal shards in plastic matrices and evaluates their neutron detection capabilities and gamma rejection, highlighting potential improvements over existing detectors.

Findings

Scintillating detector has 0.4% neutron efficiency and very low gamma sensitivity.

Nonscintillating detector has 0.7% neutron efficiency with comparable gamma rejection.

Doubling neutron efficiency could make these detectors competitive with 3He tubes.

Abstract

We present a method for detecting neutrons using scintillating lithium gadolinium borate crystal shards in a plastic matrix while maintaining high gamma rejection. We have procured two cylindrical detectors, 5"\times5", containing 1% crystal by mass. Crystal shards have a typical dimension of 1 mm. One detector was made with scintillating plastic, and one with nonscintillating plastic. Pulse shape analysis was used to reject gamma ray backgrounds. The scintillating detector was measured to have an intrinsic fast fission neutron efficiency of 0.4% and a gamma sensitivity of less than 2.3 \times 10-9, while the nonscintillating detector had a neutron efficiency of 0.7% and gamma sensitivity of (4.75\pm3.94)\times10-9. We determine that increasing the neutron detection efficiency by a factor of 2 will make the detector competitive with moderated 3He tubes, and we discuss several simple and straightforward methods for obtaining or surpassing such an improvement. We end with a discussion of possible applications, both for the scintillating-plastic and nonscintillating-plastic detectors.