Charged-particle detection efficiencies of close-packed CsI arrays

TL;DR

This paper uses GEANT4 simulations to analyze the efficiency of detecting full energies of light charged particles in close-packed CsI detector arrays, highlighting effects of scattering, nuclear reactions, and array geometry.

Contribution

It provides detailed efficiency calculations for CsI arrays, considering effects of scattering, nuclear reactions, and array packing, aiding in detector design and data correction.

Findings

Efficiency decreases exponentially with particle range.

Efficiency losses are similar for hydrogen and helium isotopes.

Position-dependent efficiency losses occur at crystal boundaries.

Abstract

Detector efficiency determination is essential to correct the measured yields and extract reliable cross sections of particles emitted in nuclear reactions. We investigate the efficiencies for measuring the full energies of light charged particle in arrays of CsI crystals employed in particle detection arrays such as HiRA, LASSA and MUST2. We perform these simulations with a GEANT4 Monte Carlo transport code implemented in the NPTool framework. Both Coulomb multiple scattering and nuclear reactions within the crystal can significantly reduce the efficiency of detecting the full energy of high energy particles. The calculated efficiencies decrease exponentially as a function of the range of the particle and are quite similar for both the hydrogen ($p, d, t$) and helium ($^3$He, $\alpha$) isotopes. The use of a close-packed array introduces significant position dependent efficiency losses at the interior boundaries between crystals that need to be considered in the design of an array and in the efficiency corrections of measured energy spectra.