Summer Research 2021 - Barkotel Zemenu, YC ‘24

scientist working at lab setup

I’m doing nuclear physics research with Professor David Moore at the nEXO (next Enriched Xenon Observatory) R&D laboratory in Wright Lab, focusing on the neutrinoless double-beta decay of Xenon-136. My current research is on the Outgassing Setup, where I study the outgassing rate of several samples in order to select ideal materials for the upcoming nEXO detector.

The nEXO project is a proposed experiment aimed at detecting neutrinoless double beta decay (0νββ), a hypothesized nuclear process that would demonstrate that neutrinos are their own antiparticles—this implication, in turn, provides a glimpse into physics beyond the Standard Model. nEXO will use tonnes of liquid xenon enriched with Xe-136, one of the potential 0νββ decaying isotopes, and will operate as a time projection chamber (TPC).

In order to accomplish its goal of detecting 0νββ, nEXO requires an electron lifetime of at least 10ms. A term used to quantify the fraction of charge that is collected from an event, the electron lifetime is inversely correlated with the concentration of electronegative impurities in the liquid xenon. These impurities exist in the detector because they are outgassed from the materials that make up the TPC, such as plastics and adhesives.

This is where my current research comes in. I measure and analyze the diffusion of various gas-material combinations in order to determine their activation energies and diffusion constants; these, in turn, quantify the outgassing of each potential material. The upshot is developing a model that compares the diffusion coefficient of various gases through each nEXO sample. This selection enables my lab to determine which samples best limit the presence of impurities in the detector and result in a greater electron lifetime. The ultimate goal is to ensure that the nEXO detector is accurately designed to pinpoint 0νββ, should it occur.

External Link: (I highly recommend the PDF at the bottom of the page, “In Search of No Neutrinos”! Colloquial and brief, it’s intended for a broad, popular audience.)