Characterization of Silicon Photomultipliers for the UCN?? Experiment

The UCN?? experiment held at Los Alamos National Laboratory works to precisely measuring the lifetime of the neutron which has implications for other fields such as Cosmology, Nuclear Physics and Particle Physics. Because UCN??+, the upgrade for the existing experiment, will upscale the number of stored ultracold neutrons (UCN), an increase in detectors will be needed to properly catalogue individual events. A portion of the paper is contributed to the data analysis of silicon photomultipliers and other observed characteristics. We produce single photoelectron spectra for the candidate SiPMs and find good performance as required for the detector under development. This performance, along with a fast, high light output scintillator is needed to handle the high rates we expect to encounter in the improved UCN?? experiment. This paper will also describe the experiment of the data set used which mimicked a high neutron count environment with and without SiPM cooling to reduce dark counts.