Simulation and design of a neutron detector based on Boron-Loaded linear alkyl benzene (LAB) liquid scintillator

Abstract

A Boron-Loaded linear alkyl benzene (LAB) liquid scintillator (LS) neutron detector has been designed to detect neutrons in high gamma field environment. The detector is made robust by piping the light from a remotely located LS module by an optical fibre. Here we describe a GEANT4 based model to optimize the design of the LS detector. This model includes the physics of neutron interaction with Boron-10, light scintillation by the LAB and light transport in the optical fiber. All the detector components including the scintillator, light guides and an approximation of the photomultiplier tube response, are simulated. The results show that for unidirectional beam of thermal neutrons, a small detector with 70 % neutron detection efficiency can be achieved by loading the LAB with 4.5% Boron-10 and by using a 2 meter optical fibre. The simulated output results are compared to actual measurement.