Speaker
Description
The PICO experiment is a leading direct dark matter search that uses superheated Freon to identify interactions between dark matter particles and ordinary matter. These detectors are bubble chambers, where a potential dark matter particle can scatter off a nucleus and impart an amount of localized energy above a threshold. This causes a bubble nucleation in the superheated fluid, most commonly C$_3$F$_8$ in PICO. The resulting phase transition is optically and acoustically recorded, with acoustic sensors providing excellent discrimination between nucleations from nuclear recoils (neutrons and dark matter) and those from alphas. Our next-generation tonne-scale PICO detector, PICO-500, is currently under construction and is scheduled for commissioning at SNOLAB in Ontario, in 2026.
A significant source of background events arise from wall nucleations (bubbles that form near or on the vessel surfaces) which reduce both detector livetime and exposure. My research focuses on understanding the nucleation mechanisms underlying these wall events, whose origins remain largely unknown. This involves developing and testing theoretical models of bubble nucleation, performing experimental studies, and analyzing existing detector data to identify correlations or potential causes. Our current theories find the higher wall rates could result from a modified Seitz threshold, radioactive isotopes in the detector, or surface defects. Ultimately, this work aims to understand bubble nucleation mechanisms and improve the sensitivity of dark matter searches for PICO-500.
| Keyword-1 | Dark Matter |
|---|---|
| Keyword-2 | WIMPs |
| Keyword-3 | Bubble Chambers |