UCLA Dark Matter 2023

Dark matter search in DEAP-3600: results and prospects

31 Mar 2023, 09:00

15m

PAB- 1-425 (UCLA)

Talk Non-directional direct dark matter detection SESSION 10: Direct Detection: status of liquid/gas WIMP detectors (CHAIR: Alvine Kamaha -UCLA)

Speaker

Dr Michela Lai

Description

DEAP-3600 is the largest running dark matter detector filled with liquid argon, set at SNOLAB in Sudbury, Canada, 2 km underground. Since 2019 the experiment has held the most stringent exclusion limit in argon for WIMPs above 20 GeV/c${}^2$. Such a result is a consequence of the large detector exposure and the extraordinary rejection power achievable in liquid argon against electron recoil backgrounds. DEAP-3600 demonstrated the discrimination power of pulse shape discrimination to the strongest precision to date, with a leakage probability as low as 10${}^{-10}$ for a nuclear recoil acceptance of 50 % at about 20 keV of deposited energy.
Recently, the WIMP analysis has been revised in terms of a non-relativistic effective field theory framework in correlation with non-standard velocity distributions in the halo, as suggested by the substructures observed with Gaia and the Sloan Sky Digital Survey. DEAP-3600 set the world's best exclusion limit for xenon-phobic dark matter scenarios. Moreover, a custom-developed analysis has recently pointed out the extraordinary sensitivity to ultra-heavy, multi-scattering dark matter candidates, resulting in world-leading exclusion limits on two composite dark matter candidates up to Planck-scale masses.
In parallel with ongoing analysis, involving both dark matter searches and measurements on the ${}^{39}$Ar $\beta$ decay spectrum and activity, the detector is undergoing upgrades with the aim to further mitigate the alpha-induced scintillation in the neck of the detector, which has limited the sensitivity to WIMPs up to now. Such R&D, including the pyrene coating of the flow guides and the external cooling system, will decrease this background and eventually enhance the detector sensitivity in the upcoming WIMP search.

Presentation materials

DEAP_ucla2023-compressed.pdf