YAP:Ce scintillator as an absolute ultracold neutron detector

TL;DR

This paper introduces a new $^{10}$B-coated YAP:Ce scintillator optimized for ultracold neutron detection, highlighting its high efficiency, fast decay time, and potential advantages over traditional detectors in neutron lifetime experiments.

Contribution

The development and characterization of a novel $^{10}$B-coated YAP:Ce scintillator for ultracold neutron detection, demonstrating improved efficiency and suitability for neutron lifetime measurements.

Findings

Neutron counting efficiency of 86.82% with $^{10}$B coating.

YAP:Ce scintillator counts 8-28% more UCNs than ZnS screens.

Measured Birks' coefficient and light loss characteristics.

Abstract

The upcoming UCNProBe experiment at Los Alamos National Laboratory will measure the $\beta$-decay rate of free neutrons with different systematic uncertainties than previous beam-based neutron lifetime experiments. We have developed a new $^{10}$B-coated YAP:Ce scintillator whose properties are presented. The advantage of the YAP:Ce scintillator is its high Fermi potential, which reduces the probability for upscattering of ultracold neutrons, and its short decay time, which is important at high counting rates. Birks' coefficient of YAP:Ce was measured to be ($5.56^{+0.05}_{-0.30})\times 10^{-4}$ cm/MeV and light losses due to 120 nm of $^{10}$B-coating to be about 60%. The loss of light from YAP:Ce due to transmission through deuterated polystyrene scintillator was about 50%. The efficiency for counting neutrons that are captured on the $^{10}$B coating is (86.82 $\pm$ 2.61)%. Measurement with ultracold neutrons showed that YAP:Ce crystal counted 8% to 28% more UCNs compared to ZnS screen. This may be due to an uneven coating of $^{10}$B on the rough surface.