Professor Jocelyn Monroe

Abstract:

The Dark Matter Time Projection Chamber (DMTPC) collaboration is developing a low pressure gas TPC for detecting Weakly Interacting Massive Particle (WIMP)-nucleon interactions. Optical readout with CCD cameras allows for the detection of the daily modulation of the direction of the dark matter wind. In order to reach sensitivities required for WIMP detection, the detector needs to minimize backgrounds from electron recoils. This paper demonstrates that a simplified CCD analysis achieves 7.3×10 ^-5 rejection of electron recoils while a charge analysis yields an electron rejection factor of 3.3×10 ^-4 for events with ²⁴¹Am-equivalent ionization energy loss between 40 keV and 200 keV. A combined charge and CCD analysis yields a background-limited upper limit of 1.1×10 ^-5 (90% confidence level) for the rejection of γ and electron events. Backgrounds from alpha decays from the field cage are eliminated by introducing a veto electrode that surrounds the sensitive region in the TPC. CCD-specific backgrounds are reduced more than two orders of magnitude when requiring a coincidence with the charge readout. © 2012 Elsevier B.V.

Abstract:

The Dark Matter Time Projection Chamber (DMTPC) collaboration has developed a direction-sensitive detector for tracking low-energy nuclear recoils. A large-scale version of this type of detector has potential to make a definitive directional detection of dark matter, as well as interesting possibilities for the first detection of ⁴⁰K geo-neutrinos. © 2012 Elsevier B.V.

Abstract:

The DMTPC directional dark matter detection experiment is a low-pressure CF4 gas time projection chamber, instrumented with charge and scintillation photon readout. This detector design strategy emphasizes reconstruction of WIMPinduced nuclear recoil tracks, in order to determine the direction of incident dark matter particles. Directional detection has the potential to make the definitive observation of dark matter using the unique angular signature of the dark matter wind, which is distinct from all known backgrounds. This talk will review the experimental technique and current status of DMTPC. © 2012 American Institute of Physics.

Abstract:

The SciBooNE and MiniBooNE collaborations report the results of a ν μ disappearance search in the Δm2 region of 0.5-40eV2. The neutrino rate as measured by the SciBooNE tracking detectors is used to constrain the rate at the MiniBooNE Cherenkov detector in the first joint analysis of data from both collaborations. Two separate analyses of the combined data samples set 90% confidence level (CL) limits on ν μ disappearance in the 0.5-40eV2 Δm2 region, with an improvement over previous experimental constraints between 10 and 30eV2. © 2012 American Physical Society.