Location via proxy:   [ UP ]  
[Report a bug]   [Manage cookies]                

Assessing the discovery potential of directional detection of dark matter

J. Billard, F. Mayet, and D. Santos
Phys. Rev. D 85, 035006 – Published 7 February 2012
PDFHTMLExport Citation
Abstract
Authors
Article Text
  • INTRODUCTION
  • DIRECTIONAL DETECTION FRAMEWORK
  • THE PROFILE LIKELIHOOD RATIO TEST…
  • OPTIMIZING DIRECTIONAL DETECTION
  • PROSPECT
  • CONCLUSION
  • ACKNOWLEDGEMENTS
    • References

    Abstract

    There is a worldwide effort toward the development of a large time projection chamber devoted to directional dark matter detection. All current projects are being designed to fulfill a unique goal: identifying weakly interacting massive particle (WIMP) as such by taking advantage of the expected direction dependence of WIMP-induced events toward the constellation Cygnus. However, such proof of discovery requires a careful statistical data treatment. In this paper, the discovery potential of forthcoming directional detectors is addressed by using a frequentist approach based on the profile likelihood ratio test statistic. This allows us to estimate the expected significance of a dark matter detection taking into account astrophysical and experimental uncertainties. We show that the energy threshold and the background contamination are key experimental issues for directional detection, while angular resolution and sense recognition efficiency only mildly affect the sensitivity and the energy resolution is unimportant. This way, we found that a 30 kg.year CF4 directional experiment could reach a 3σ sensitivity at 90% C.L. down to 10−5  pb and 3.10−4  pb for the WIMP-proton axial cross section in the most optimistic and pessimistic detector performance case, respectively.

    • Figure
    • Figure
    • Figure
    • Figure
    • Figure
    • Figure
    • Figure
    8 More
    • Received 27 October 2011

    DOI:https://doi.org/10.1103/PhysRevD.85.035006

    © 2012 American Physical Society

    Authors & Affiliations

    J. Billard*, F. Mayet, and D. Santos

    • Laboratoire de Physique Subatomique et de Cosmologie, Université Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut Polytechnique de Grenoble, Grenoble, France

    • *billard@lpsc.in2p3.fr

    Article Text (Subscription Required)

    Click to Expand

    References (Subscription Required)

    Click to Expand
    Issue

    Vol. 85, Iss. 3 — 1 February 2012

    Reuse & Permissions
    Access Options
    Author publication services for translation and copyediting assistance advertisement

    Authorization Required

    Log In
    Other Options
    ×

    Images

    • Figure 1
      Figure 1
      Probability density functions of q0 under the background-only hypothesis H0 with/without (blue solid line/black dotted line) considering astrophysical uncertainties, estimated with 10 000 Monte Carlo simulations. The red long-dashed line corresponds to the χ12 distribution.Reuse & Permissions
    • Figure 2
      Figure 2
      Normalized distributions of the significance f(Z) with/without (blue solid line/black dotted line) considering astrophysical uncertainties. Distributions were generated using 10 000 Monte Carlo simulations with 100 WIMP events and 50 background events with a WIMP mass mχ=50  GeV/c2. We found mean values of the significance of 9.2 and 9.3 and a 90% confidence lower limit Z90 of 7.9 and 5.9, respectively.Reuse & Permissions
    • Figure 3
      Figure 3
      Evolution of the mean significance E(Z) as a function of the expected WIMP fraction λ=Ns/(Ns+Nb) for three different values of the expected total number of events Ntot=100 (black solid line), 50 (red dotted line), and 25 (blue long-dashed line). This study has been done by considering a WIMP mass of 50  GeV/c2.Reuse & Permissions
    • Figure 4
      Figure 4
      Lower bound of the 3σ discovery region at 90% C.L. in the (mχ, log10(σp)) plane. Black line presents the background-free case, while the blue dashed line presents the same region with 10 background events per year per kg. For convenience, the curves of isonumber of WIMP events are presented (dashed lines) in the case of 5, 30, and 150 WIMP events.Reuse & Permissions
    • Figure 5
      Figure 5
      Mean significance E(Z) as a function of the energy threshold, for four different WIMP masses: mχ=5 (black solid line), 10 (red dotted line), 20 (blue long-dashed line), and 50  GeV/c2 (green short-dashed line). We have considered a constant background rate of Rb=10  evts/kg/year and different values of σp to get μs=100 events for each WIMP mass at Eth=0  keV.Reuse & Permissions
    • Figure 6
      Figure 6
      Lower bound of the 3σ discovery region at 90% C.L. in the (mχ, log10(σp)) plane for two different cases: Eth=0  keV (black solid line) and Eth=50  keV (blue long-dashed line) without background events. For convenience, the curves of isonumber of WIMP events are presented in the Eth=0  keV case (black dashed lines) and in the Eth=50  keV case (blue dashed lines).Reuse & Permissions
    • Figure 7
      Figure 7
      Mean significance as a function of ϵHT for two different cases (Ns=100, Nb=0) (black solid line) and (Ns=100, Nb=100) (blue long-dashed line). A WIMP mass of 50  GeV/c2 has been considered for this study.Reuse & Permissions
    • Figure 8
      Figure 8
      Lower bound of the 3σ discovery region at 90% C.L. in the (mχ, log10(σp)) plane for two different cases: ϵHT=100% (black solid line) and ϵHT=0% (blue long-dashed line) without background events. For convenience, the curves of isonumber of WIMP events are presented (dashed lines) in the case of Ns=5, 30, and 120.Reuse & Permissions
    • Figure 9
      Figure 9
      Mean significance as a function of the angular resolution σγ for different cases (Ns=100, Nb=0) (black solid line) and (Ns=100, Nb=0) (blue long-dashed line). A WIMP mass of 50  GeV/c2 has been considered for this study.Reuse & Permissions
    • Figure 10
      Figure 10
      Lower bound of the 3σ discovery region at 90% C.L. in the (mχ, log10(σp)) plane for two different cases: σγ=0° (black solid line) and σγ=60° (blue long-dashed line) without background events. For convenience, the curves of isonumber of WIMP events are presented (dashed lines) in the case of 5, 30, and 100 WIMP events.Reuse & Permissions
    • Figure 11
      Figure 11
      Mean significance as a function of σEr for different cases (Ns=100, Nb=0) (solid lines) and (Ns=100, Nb=100) (long-dashed lines) according to two different WIMP masses: mχ=20  GeV/c2 (black lines) and mχ=100  GeV/c2 (blue lines).Reuse & Permissions
    • Figure 12
      Figure 12
      Mean significance as a function of the background slope Eback for 5 different values of sense recognition efficiencies (from top to bottom): ϵHT=100%, 75%, 50%, 25%, and 0%. A WIMP mass of 50  GeV/c2 with 100 expected WIMP events and no background contamination has been considered in this study.Reuse & Permissions
    • Figure 13
      Figure 13
      Mean significance as a function of the background slope Eback for 5 different values of angular resolution (from top to bottom): σγ=0°, 15°, 30°, 45°, and 60°. A WIMP mass of 50  GeV/c2 with 100 expected WIMP events and no background contamination has been considered in this study.Reuse & Permissions
    • Figure 14
      Figure 14
      Lower bound of the 3σ discovery region at 90% C.L. in the (mχ, log10(σp)) plane for three different cases: (Eback→+∞  keV, ϵHT=100%) (black solid line), (Eback=17.4  keV, ϵHT=100%) (blue long-dashed line), and (Eback=17.4  keV, ϵHT=0%) (red dotted line) without background events. For convenience, the curves of isonumber of WIMP events are presented (dashed lines) in the case of 5, 30, and 220 WIMP events.Reuse & Permissions
    • Figure 15
      Figure 15
      Lower bound of the 3σ discovery region at 90% C.L. in the (mχ, log10(σp)) plane for the two detectors A (red solid line) and B (blue solid line), considering a 30 kg.year exposure. The theoretical region, obtained within the framework of the constrained minimal supersymmetric model, is taken from 87 and shown as the green contour. Constraints from collider data and relic abundance are accounted for. Exclusion limits from direct searches are also shown: SIMPLE [13] (black solid line), COUPP [14] (dotted line), and KIMS [16] (dashed line).Reuse & Permissions
    ×

    Sign up to receive regular email alerts from Physical Review D

    Log In

    Cancel
    ×

    Search

    Article Lookup

    Paste a citation or DOI
    Enter a citation
    ×