Professor Jocelyn Monroe

Abstract:

Direction measurement of weakly interacting massive particles in time-projection chambers can provide definite evidence of their existence and help to determine their properties. This article demonstrates several concepts for charge amplification in time-projection chambers that can be used in direction-sensitive dark matter search experiments. We demonstrate reconstruction of the "head-tail" effect for nuclear recoils above 100 keV, and discuss the detector performance in the context of dark matter detection and scaling to large detector volumes. © 2008 Elsevier B.V. All rights reserved.

Abstract:

Present and planned dark matter detection experiments search for WIMP-induced nuclear recoils in poorly known background conditions. In this environment, the maximum gap statistical method provides a way of setting more sensitive cross section upper limits by incorporating known signal information. We give a recipe for the numerical calculation of upper limits for planned directional dark matter detection experiments, that will measure both recoil energy and angle, based on the gaps between events in two-dimensional phase space. © 2008 The American Physical Society.

Abstract:

This paper presents a measurement of the ratio of photon to electron production and the scintillation spectrum in a popular gas for time projection chambers, carbon tetrafluoride (CF4), over the range of 200-800 nm; the ratio is measured to be 0.34 ± 0.04. This result is of particular importance for a new generation of dark matter time projection chambers with directional sensitivity which use CF4 as a fill gas. © 2008 Elsevier B.V. All rights reserved.