Measuring Fast Neutrons with Large Liquid Scintillation Detector for Ultra-low Background Experiments

TL;DR

This paper presents a large liquid scintillation detector designed for ultra-low background experiments, demonstrating effective neutron detection, calibration, and neutron-gamma discrimination in an underground setting.

Contribution

The study introduces a 12-liter liquid scintillator detector with enhanced light collection and pulse shape discrimination for neutron-gamma separation at high energies.

Findings

Successful calibration with point sources and cosmic-ray muons up to 20 MeV

First demonstration of neutron-gamma discrimination in a large liquid scintillator

Effective neutron detection in an underground laboratory environment

Abstract

We developed a 12-liter volume neutron detector filled with the liquid scintillator EJ301 that measures neutrons in an underground laboratory where dark matter and neutrino experiments are located. The detector target is a cylindrical volume coated on the inside with reflective paint (95% reflectivity) that significantly increases the detector's light collection. We demonstrate several calibration techniques using point sources and cosmic-ray muons for energies up to 20 MeV for this large liquid scintillation detector. Neutron-gamma separation using pulse shape discrimination with a few MeV neutrons to hundreds of MeV neutrons is shown for the first time using a large liquid scintillator.