Angular signatures for galactic halo weakly interacting massive particle scattering in direct detectors: Prospects and challenges
29 Jan 2001-Physical Review D (American Institute of Physics Publising LLC)-Vol. 63, Iss: 4, pp 043507
TL;DR: In this paper, the authors provide a formalism that allows a calculation of the expected angular distribution of events in terrestrial detectors with angular sensitivity for any incident distribution of galactic halo dark matter.
Abstract: Angular sensitivity can provide a key additional tool which might allow unambiguous separation of a signal due to galactic halo WIMPs from other possible backgrounds in direct detectors. We provide a formalism that allows a calculation of the expected angular distribution of events in terrestrial detectors with angular sensitivity for any incident distribution of galactic halo dark matter. This can be used as an input when studying the sensitivity of specific detectors to halo WIMPs. We utilize this formalism to examine the expected signature for WIMP dark matter using a variety of existing analytic halo models in order to explore how uncertainty in the galactic halo distribution impact on the the event rates that may be required to separate a possible WIMP signal from terrestrial backgrounds. We find that as few as 30 events might be required to disentangle the signal from backgrounds if the WIMP distribution resembles an isothermal sphere distribution. On the other hand, for certain halo distributions, even detectors with fine angular resolution may require in excess of a 100--400 events to distinguish a WIMP signal from backgrounds using angular sensitivity. We also note that for finite thresholds the different energy dependence of spin-dependent scattering cross sections may require a greater number of events to discern a WIMP signal than for spin independent interactions. Finally, we briefly describe ongoing studies aimed at developing strategies to better exploit angular signatures, and the use of N-body simulations to better model the expected halo distribution in predicting the expected signature for direct WIMP detectors.
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TL;DR: A review of the physics of direct detection of dark matter, discussing the roles of both the particle physics and astrophysics in the expected signals, is given in this article, where the authors discuss the practical formulas needed to interpret a modulating signal.
Abstract: Direct detection experiments, which are designed to detect the scattering of dark matter off nuclei in detectors, are a critical component in the search for the Universe’s missing matter. This Colloquium begins with a review of the physics of direct detection of dark matter, discussing the roles of both the particle physics and astrophysics in the expected signals. The count rate in these experiments should experience an annual modulation due to the relative motion of the Earth around the Sun. This modulation, not present for most known background sources, is critical for solidifying the origin of a potential signal as dark matter. The focus is on the physics of annual modulation, discussing the practical formulas needed to interpret a modulating signal. The dependence of the modulation spectrum on the particle and astrophysics models for the dark matter is illustrated. For standard assumptions, the count rate has a cosine dependence with time, with a maximum in June and a minimum in December. Well-motivated generalizations of these models, however, can affect both the phase and amplitude of the modulation. Shown is how a measurement of an annually modulating signal could teach us about the presence of substructure in the galactic halo or about the interactions between dark and baryonic matter. Although primarily a theoretical review, the current experimental situation for annual modulation and future experimental directions is briefly discussed.
366 citations
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...Directional detectors are particularly useful in mapping out the local dark matter distribution (Copi, Heo, and Krauss, 1999; Copi and Krauss, 2001; Morgan, Green, and Spooner, 2005; Alenazi and Gondolo, 2008; Alves, Hedri, and Wacker, 2012; Bozorgnia, Gelmini, and Gondolo, 2012; Lee and Peter,…...
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TL;DR: In this paper, the authors review the astrophysics and cosmological evidence for nonbaryonic dark matter (DM) and survey the underlying particle theories that provide some guidance about expected event rates, and the future prospects for the discovery of DM.
Abstract: ▪ Abstract This article reviews the astrophysics and cosmological evidence for nonbaryonic dark matter (DM). It covers historical, current, and future experiments that look for direct evidence of particle DM. In addition, it surveys the underlying particle theories that provide some guidance about expected event rates, and the future prospects for the discovery of DM. A number of recent theoretical papers, making calculations in SUSY-based frameworks, show a spread of many (>5) orders of magnitude in the possible interaction rates for models consistent with existing cosmological and accelerator bounds. Within this decade, it seems likely that DM searches will be successful, or at the very least rule out a broad class of the currently most favored DM models.
272 citations
University of Grenoble1, University of Nottingham2, Wellesley College3, University of Lyon4, University of Amsterdam5, University of California, Los Angeles6, University of Utah7, Université Paris-Saclay8, University of Paris9, Princeton University10, Broad Institute11, University of New Mexico12, Royal Holloway, University of London13, University of Warwick14, Ohio State University15, University of Hawaii16
TL;DR: In this article, the authors review the potential of directional detectors for detecting and characterizing WIMPs and present a powerful tool for demonstrating the Galactic origin of nuclear recoils and hence unambiguously detecting Dark Matter.
209 citations
01 Jan 2004
TL;DR: In this paper, the authors review the astrophysics and cosmological evidence for nonbaryonic dark matter (DM) and survey the underlying particle theories that provide some guidance about expected event rates, and the future prospects for the discovery of DM.
Abstract: ▪ Abstract This article reviews the astrophysics and cosmological evidence for nonbaryonic dark matter (DM). It covers historical, current, and future experiments that look for direct evidence of particle DM. In addition, it surveys the underlying particle theories that provide some guidance about expected event rates, and the future prospects for the discovery of DM. A number of recent theoretical papers, making calculations in SUSY-based frameworks, show a spread of many (>5) orders of magnitude in the possible interaction rates for models consistent with existing cosmological and accelerator bounds. Within this decade, it seems likely that DM searches will be successful, or at the very least rule out a broad class of the currently most favored DM models.
186 citations
TL;DR: In this article, the number of events required to distinguish a WIMP signal from an isotropic background when the uncertainty in the reconstruction of the nuclear recoil direction is included in the calculation of the expected signal was examined.
Abstract: The direction dependence of the event rate in WIMP direct detection experiments provides a powerful tool for distinguishing WIMP events from potential backgrounds. We use a variety of (nonparametric) statistical tests to examine the number of events required to distinguish a WIMP signal from an isotropic background when the uncertainty in the reconstruction of the nuclear recoil direction is included in the calculation of the expected signal. We consider a range of models for the Milky Way halo, and also study rotational symmetry tests aimed at detecting nonsphericity/isotropy of the Milky Way halo. Finally we examine ways of detecting tidal streams of WIMPs. We find that if the senses of the recoils are known then of order ten events will be sufficient to distinguish a WIMP signal from an isotropic background for all of the halo models considered, with the uncertainties in reconstructing the recoil direction only mildly increasing the required number of events. If the senses of the recoils are not known the number of events required is an order of magnitude larger, with a large variation between halo models, and the recoil resolution is now an important factor. The rotational symmetry tests require of order a thousand events to distinguish between spherical and significantly triaxial halos, however a deviation of the peak recoil direction from the direction of the solar motion due to a tidal stream could be detected with of order a hundred events, regardless of whether the sense of the recoils is known.
140 citations