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Shawn Westerdale (PRINCETON) "Detecting Dark Matter with DarkSide-50"
January 19, 2016 @ 4:00 pm - 5:00 pm
Dark matter constitutes 85% of the matter in the universe, yet despite its abundance, very little is known about it. One popular theory is that dark matter is made of Weakly Interacting Massive Particles, or WIMPs. Due to the low cross section for WIMP-nucleus interactions, the event rate of WIMPs in a detector is expected to be very low. This means that detectors must have extraordinarily low background rates and good background rejection in order to be able to detect these rare events above their background.
DarkSide-50 is a 50 kg liquid argon time project chamber, nested inside of a 30 tonne boron-loaded liquid scintillator neutron veto, which is inside a 1000 tonne water Cherenkov muon veto. Since neutrons can leave a signal identical to what is expected from WIMPs, neutrons are the most dangerous background to such an experiment. I will talk about the latest results from the DarkSide-50 detector, which recently published results from 120 days of running background free. This talk will also have a focus on the design and performance of the neutron veto system that enables the detector to remain free of neutron backgrounds by vetoing neutrons with > 99.2% efficiency.