Professor Jocelyn Monroe

Abstract:

Directional detection of dark matter can provide unambiguous observation of dark matter interactions even in the presence of background. This article presents an experimental method to measure the direction tag ("head-tail") of the dark matter wind by detecting the scintillation light created by the elastic nuclear recoils in the scattering of dark matter particles with the detector material. The technique is demonstrated by tagging the direction of the nuclear recoils created in the scattering of low-energy neutrons with CF4 in a low-pressure time-projection chamber that is developed by the DMTPC collaboration. The measurement of the decreasing ionization rate along the recoil trajectory provides the direction tag of the incoming neutrons, and proves that the "head-tail" effect can be observed. © 2007 Elsevier B.V. All rights reserved.

Abstract:

We present new results with a prototype detector that is being developed by the DMTPC collaboration for the measurement of the direction tag (head-tail) of dark matter wind. We use neutrons from a ²⁵²Cf source to create low-momentum nuclear recoils in elastic scattering with the residual gas nuclei. The recoil track is imaged in low-pressure time-projection chamber with optical readout. We measure the ionization rate along the recoil trajectory, which allows us to determine the direction tag of the incoming neutrons.

Abstract:

Neutrino coherent scattering cross sections can be as large as 10-39cm2, while current dark matter experiments have sensitivities to WIMP coherent scattering cross sections 5 orders of magnitude smaller; future experiments plan to have sensitivities to cross sections as small as 10-48cm2. With large target masses and few keV recoil energy detection thresholds, neutral current coherent scattering of solar neutrinos becomes an irreducible background in dark matter searches. In the current zero-background analysis paradigm, neutrino coherent scattering will limit the achievable sensitivity to dark matter scattering cross sections, at the level of 10-46cm2. © 2007 The American Physical Society.

Abstract:

Neutrino oscillations have been established in solar and atmospheric neutrinos, but a third signal from the LSND experiment is incompatible with three Standard Model neutrinos. The MiniBooNE experiment can confirm or refute the LSND oscillation signal with 1 × 10²¹ protons on target. While working towards the oscillation result, MiniBooNE will accumulate more than 1 × 10⁶ neutrino interactions in the 0 to 2 GeV range which will greatly increase the world's knowledge of neutrino cross sections in this energy regime. Preliminary results on the MiniBooNE νμ charged current quasi-elastic analysis are presented and compared to the NUANCE, NEUT, and NEUGEN cross section Monte Carlos. © 2004 Published by Elsevier B.V.