Measurement of Proton Quenching in a Plastic Scintillator Detector

TL;DR

This study measures the non-linear energy response of a plastic scintillator using neutron beams, extracting Birks' constants to improve modeling of neutron backgrounds in reactor neutrino detectors.

Contribution

It provides the first measurement of Birks' constants for EJ-260 scintillator over a relevant energy range, enhancing energy response models.

Findings

Determined Birks' constants for EJ-260 scintillator.

Covered a neutron energy range of 5 to 27 MeV.

Results will improve neutron background modeling in reactor detectors.

Abstract

The non-linear energy response of the plastic scintillator EJ-260 is measured with the MicroCHANDLER detector, using neutron beams of energy 5 to 27 MeV at the Triangle Universities Nuclear Laboratory. The first and second order Birks' constants are extracted from the data, and found to be $k_B = (8.70 \pm 0.93)\times 10^{-3}\ {\rm g/cm^2/MeV}$ and $k_C = (1.42 \pm 1.00) \times 10^{-5}\ {\rm (g/cm^2/MeV)^2}$. This result covers a unique energy range that is of direct relevance for fast neutron backgrounds in reactor inverse beta decay detectors. These measurements will improve the energy non-linearity modeling of plastic scintillator detectors. In particular, the updated energy response model will lead to an improvement of fast neutron modeling for detectors based on the CHANDLER reactor neutrino detector technology.