Scintillator characterization for the UCNProBe experiment*

The free neutron lifetime is typically determined using one of two methods: measuring the decay products of neutrons in a well-calibrated neutron beam (beam experiment), or counting the number of surviving neutrons stored in an ultra-cold neutron (UCN) trap over time (bottle experiment). However, the lifetime results from the two methods differ by approximately four standard deviations. The UCNProBe experiment at Los Alamos aims to resolve this difference by measuring the free neutron lifetime using stored ultra-cold neutrons (UCNs) in a material trap made of deuterated scintillator. To do so, we will attempt to measure the absolute number of UCNs within the trap and the absolute number of electrons from beta decay to within 0.1 percent precision. Critical to an accurate determination of number of UCNs is a precise determination of the dead layer thickness. In this talk, we will report the characterization of the dead layer of the scintillator and the effects of heat treatment on the dead layer thickness.