Simulations of the nEDM@SNS light collection system efficiency

Understand

A system for collecting the scintillation light produced by the capture process of ultra-cold neutrons (UCN) on polarized $^{3}$He is discussed and results from simulations of its performance are presented.

• This system will be implemented in nEDM@SNS, the experiment searching for the neutron electric dipole moment (nEDM) at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory.
• Simulation results show that the light collection system collects on average 17 photoelectrons per UCN-$^{3}$He capture event (sufficient to generate a robust signal), reconstructs the event location in the beam direction to approximately 3 cm accuracy, detects capture events with a high and spatially uniform efficiency (0.95 with 1% variation), and rejects greater than 50% of beta decay background events.