Thermal/epithermal neutron detection via LiO$_{2}$-doped fiber bundles: A computational study through GEANT4 simulations

TL;DR

This computational study explores the use of LiO₂-doped fiber bundles in detecting thermal and epithermal neutrons by simulating secondary alpha-triton pair production and optical photon collection, demonstrating their potential for neutron detection.

Contribution

The paper introduces a novel LiO₂-doped fiber bundle system for neutron detection, optimized via GEANT4 simulations, and evaluates its effectiveness for thermal and epithermal neutrons.

Findings

Optimal fiber array configuration identified for thermal neutrons.

LiO₂-doped fibers effectively produce secondary alpha-triton pairs.

Fiber bundles can detect both thermal and epithermal neutrons.

Abstract

One of the neutron capture processes in lithium or lithium-doped materials leads to the production of secondary alpha-triton pairs. The counts of these secondary charged particle pairs in the presence of thermal/epithermal neutrons indirectly give access to detecting the primary incident neutrons with the aid of the plastic scintillators by reminding that both these secondary alphas and tritons deposit their entire kinetic energy within a short range. In this study, we modify the polystyrene fiber core of Kuraray Y11-200(M) by doping with 10 wt.$\%$ LiO$_{2}$. We investigate a fiber bundle system hinged on 10 wt.$\%$ LiO$_{2}$-doped Kuraray Y11-200(M) fibers via the GEANT4 simulations by targeting the detection of the incident thermal/epithermal neutrons through the generation of the secondary alpha-triton pairs. First, we estimate an optimal number of fiber arrays by using a monoenergetic beam of thermal neutrons with a kinetic energy of 0.025 eV and we count the number of secondary alpha-triton pairs. Subsequently, we insert a pixelated photo-sensor on both ends of the fiber bundle in order to collect the entrapped optical photons. In addition to the thermal neutrons, we also explore the detection of epithermal neutrons with a kinetic energy of 1 eV by utilizing a combination of the 10 wt.$\%$ LiO$_{2}$-doped Kuraray Y11-200(M) fiber bundles and the neutron absorption layers. We demonstrate that the LiO$_{2}$-doped plastic scintillating fiber bundles are instrumental for the detection of thermal/epithermal neutrons in diverse applications.