Simulating performance of a nuclear physics detector

The Standard Model of particle physics is a theory which has been devised by physicists to explain how our world functions at the most basic level. Still, despite nearly a century of research, physicists continue to construct elaborate experiments to solve some of the theory's remaining mysteries. nEXO, the next Enriched Xenon Observatory, is one of these experiments.

As its name suggests, nEXO will use approximately 5000 kilograms of enriched xenon to observe neutrinoless double beta decay, a hypothetical type of radioactive decay. Never having been observed, neutrinoless double beta decay is known to be incredibly rare – if it happens at all. This fact causes background rejection to be one of the biggest challenges facing nEXO. Anything which could generate a false-positive in the detector must be blocked, eliminated, or identified in order to operate with precision.

Radon introduced into the xenon is one source of background. Radon radioactively decays through several isotopes including bismuth, an isotope which also decays and emits energy very similar to neutrinoless double beta decay. Simulating how much interference bismuth will contribute and how efficiently nEXO can separate these bismuth decays from neutrinoless double beta decay events will offer information to be considered in the experiment's final design.