Quenching Factor for Low Energy Nuclear Recoils in a Plastic Scintillator

TL;DR

This study measures the quenching factor for low-energy nuclear recoils in a plastic scintillator, providing data crucial for neutron detection applications and comparing results with theoretical models.

Contribution

It presents the first detailed measurement of the energy-dependent quenching factor for low-energy nuclear recoils in a specific plastic scintillator, using experimental data and Monte Carlo simulations.

Findings

Quenching factor above 300 keV fits Birks' model with kB = 0.014 g/MeVcm^2.

Below 300 keV, the quenching factor decreases more steeply than Birks' model predicts.

Data enhances understanding of plastic scintillator response to low-energy neutrons.

Abstract

Plastic scintillators are widely used in industry, medicine and scientific research, including nuclear and particle physics. Although one of their most common applications is in neutron detection, experimental data on their response to low-energy nuclear recoils are scarce. Here, the relative scintillation efficiency for neutron-induced nuclear recoils in a polystyrene-based plastic scintillator (UPS-923A) is presented, exploring recoil energies between 125 keV and 850 keV. Monte Carlo simulations, incorporating light collection efficiency and energy resolution effects, are used to generate neutron scattering spectra which are matched to observed distributions of scintillation signals to parameterise the energy-dependent quenching factor. At energies above 300 keV the dependence is reasonably described using the semi-empirical formulation of Birks and a kB factor of (0.014+/-0.002) g/MeVcm^2 has been determined. Below that energy the measured quenching factor falls more steeply than predicted by the Birks formalism.