Würzburg 2018 – scientific programme

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T: Fachverband Teilchenphysik

T 6: Suche nach dunkler Materie I

T 6.3: Talk

Monday, March 19, 2018, 16:35–16:50, Philo-HS6

Background suppression through pulseshape analysis in the DEAP-3600 dark matter detector — •Moritz Burghardt¹ and DEAP Collaboration² — ¹TU München — ²SNOLAB, Canada

DEAP-3600 is a dark matter direct detection experiments at SNOLAB, Canada using a single phase liquid argon target. Upon energy deposition of ionising particles, liquid argon emits light through the decay of short-lived singlet state and long-lived triplet state excimers. This light makes up the only dark matter signal channel and is detected by an array of 255 photomultiplier tubes. In order to reach the projected sensitivity to WIMP-nucleon cross sections of 10⁻⁴⁶ cm² for 100 GeV WIMPs, the electronic recoil background, which is dominated by the beta-decaying ³⁹Ar, has to be suppressed by a factor of at least 10⁻⁸. This is achieved through pulseshape discrimination (PSD): electronic recoils produce a different singlet to triplet excimer ratio than the nuclear recoil signal from a WIMP interaction, leading to different time structures of the pulse shape. In this talk, prompt-window-based and likelihood-based PSD-parameters are presented and evaluated based on their discrimination power in DEAP-3600.