skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Directional statistics for realistic weakly interacting massive particle direct detection experiments. II. 2D readout

Abstract

The direction dependence of the WIMP direct detection rate provides a powerful tool for distinguishing a WIMP signal from possible backgrounds. We study the number of events required to discriminate a WIMP signal from an isotropic background for a detector with 2-d readout using nonparametric circular statistics. We also examine the number of events needed to (i) detect a deviation from rotational symmetry, due to flattening of the Milky Way halo and (ii) detect a deviation in the mean direction due to a tidal stream. If the senses of the recoils are measured then of order 20--70 events (depending on the plane of the 2-d readout and the detector location) will be sufficient to reject isotropy of the raw recoil angles at 90% confidence. If the senses can not be measured these number increase by roughly 2 orders of magnitude (compared with an increase of 1 order of magnitude for the case of full 3-d readout). The distributions of the reduced angles, with the (time-dependent) direction of solar motion subtracted, are far more anisotropic, however, and if the isotropy tests are applied to these angles then the numbers of events required are similar to the case of 3-d readout. Amore » deviation from rotational symmetry will only be detectable if the Milky Way halo is significantly flattened. The deviation in the mean direction due to a tidal stream is potentially detectable, however, depending on the density and direction of the stream. The meridian plane (which contains the Earth's spin axis) is, for all detector locations, the optimum readout plane for rejecting isotropy. However readout in this plane can not be used for detecting flattening of the Milky Way halo or a stream with direction perpendicular to the galactic plane. In these cases the optimum readout plane depends on the detector location.« less

Authors:
;  [1];  [2]
  1. Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom)
  2. (United Kingdom)
Publication Date:
OSTI Identifier:
20774499
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 72; Journal Issue: 12; Other Information: DOI: 10.1103/PhysRevD.72.123501; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ANISOTROPY; DENSITY; DISTRIBUTION; ISOTROPY; MILKY WAY; PARTICLE IDENTIFICATION; RECOILS; SPIN; STATISTICS; SYMMETRY; TIME DEPENDENCE; WEAK INTERACTIONS

Citation Formats

Morgan, Ben, Green, Anne M., and Department of Physics and Astronomy, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield, S3 7RH. Directional statistics for realistic weakly interacting massive particle direct detection experiments. II. 2D readout. United States: N. p., 2005. Web. doi:10.1103/PhysRevD.72.123501.
Morgan, Ben, Green, Anne M., & Department of Physics and Astronomy, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield, S3 7RH. Directional statistics for realistic weakly interacting massive particle direct detection experiments. II. 2D readout. United States. doi:10.1103/PhysRevD.72.123501.
Morgan, Ben, Green, Anne M., and Department of Physics and Astronomy, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield, S3 7RH. Thu . "Directional statistics for realistic weakly interacting massive particle direct detection experiments. II. 2D readout". United States. doi:10.1103/PhysRevD.72.123501.
@article{osti_20774499,
title = {Directional statistics for realistic weakly interacting massive particle direct detection experiments. II. 2D readout},
author = {Morgan, Ben and Green, Anne M. and Department of Physics and Astronomy, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield, S3 7RH},
abstractNote = {The direction dependence of the WIMP direct detection rate provides a powerful tool for distinguishing a WIMP signal from possible backgrounds. We study the number of events required to discriminate a WIMP signal from an isotropic background for a detector with 2-d readout using nonparametric circular statistics. We also examine the number of events needed to (i) detect a deviation from rotational symmetry, due to flattening of the Milky Way halo and (ii) detect a deviation in the mean direction due to a tidal stream. If the senses of the recoils are measured then of order 20--70 events (depending on the plane of the 2-d readout and the detector location) will be sufficient to reject isotropy of the raw recoil angles at 90% confidence. If the senses can not be measured these number increase by roughly 2 orders of magnitude (compared with an increase of 1 order of magnitude for the case of full 3-d readout). The distributions of the reduced angles, with the (time-dependent) direction of solar motion subtracted, are far more anisotropic, however, and if the isotropy tests are applied to these angles then the numbers of events required are similar to the case of 3-d readout. A deviation from rotational symmetry will only be detectable if the Milky Way halo is significantly flattened. The deviation in the mean direction due to a tidal stream is potentially detectable, however, depending on the density and direction of the stream. The meridian plane (which contains the Earth's spin axis) is, for all detector locations, the optimum readout plane for rejecting isotropy. However readout in this plane can not be used for detecting flattening of the Milky Way halo or a stream with direction perpendicular to the galactic plane. In these cases the optimum readout plane depends on the detector location.},
doi = {10.1103/PhysRevD.72.123501},
journal = {Physical Review. D, Particles Fields},
number = 12,
volume = 72,
place = {United States},
year = {Thu Dec 15 00:00:00 EST 2005},
month = {Thu Dec 15 00:00:00 EST 2005}
}