Fast-neutron induced background in LaBr3:Ce detectors

TL;DR

This study measures and simulates the response of LaBr3:Ce scintillation detectors to fast neutrons in the 2-12 MeV range, providing data and models to predict neutron-induced backgrounds for various detector sizes.

Contribution

It provides experimental measurements and Monte Carlo simulations of neutron interactions in LaBr3:Ce detectors, enhancing understanding of neutron-induced backgrounds in these scintillators.

Findings

Good agreement between simulations and experimental data.

Response of LaBr3:Ce detectors characterized for 2-12 MeV neutrons.

Predictions for neutron response in different crystal sizes.

Abstract

The response of a scintillation detector with a cylindrical 1.5-inch LaBr3:Ce crystal to incident neutrons has been measured in the energy range En = 2-12 MeV. Neutrons were produced by proton irradiation of a Li target at Ep = 5-14.6 MeV with pulsed proton beams. Using the time-of-flight information between target and detector, energy spectra of the LaBr3:Ce detector resulting from fast neutron interactions have been obtained at 4 different neutron energies. Neutron-induced gamma rays emitted by the LaBr3:Ce crystal were also measured in a nearby Ge detector at the lowest proton beam energy. In addition, we obtained data for neutron irradiation of a large-volume high-purity Ge detector and of a NE-213 liquid scintillator detector, both serving as monitor detectors in the experiment. Monte-Carlo type simulations for neutron interactions in the liquid scintillator, the Ge and LaBr3:Ce crystals have been performed and compared with measured data. Good agreement being obtained with the data, we present the results of simulations to predict the response of LaBr3:Ce detectors for a range of crystal sizes to neutron irradiation in the energy range En = 0.5-10 MeV