Professor Jocelyn Monroe

Abstract:

The MiniCLEAN dark matter direct detection experiment is a single-phase liquid argon detector, instrumented with photomultiplier tubes to observe scintillation light from a 150kg fiducial mass. This detector design strategy emphasizes scalability to target masses of order 10 tons or more. The projected light yield is 6 photo-electrons per keV, which allows pulse shape discrimination to separate the electron background from a WIMP-induced nuclear recoil signal. MiniCLEAN is also designed for a liquid neon target which, in the event of a positive signal in argon, will enable an independent verification of backgrounds and provide a unique test of the expected A² dependence of the WIMP interaction rate. This talk will review the experimental technique and current status of MiniCLEAN.

Abstract:

The Dark Matter Time Projection Chamber (DMTPC) collaboration is developing a low-pressure gas TPC for detecting WIMP-nucleon interactions. DMTPC detectors use optical readout with CCD cameras to search for the daily modulation of the directional signal of the dark matter wind. An analysis of several charge readout channels has been developed to obtain additional information about ionization events in the detector. In order to reach sensitivities required for the WIMP detection, the detector needs to minimize backgrounds from electron recoils. This article shows that by using the readout of charge signals in addition to CCD readout, a preliminary statistics-limited 90% C.L. upper limit on the γ and e^- rejection factor of 5.6 × 10^-6 is obtained for energies between 40 keVee and 200 keVee.