28 research outputs found
Direct Detection of Sub-GeV Dark Matter
Direct detection strategies are proposed for dark matter particles with MeV
to GeV mass. In this largely unexplored mass range, dark matter scattering with
electrons can cause single-electron ionization signals, which are detectable
with current technology. Ultraviolet photons, individual ions, and heat are
interesting alternative signals. Focusing on ionization, we calculate the
expected dark matter scattering rates and estimate the sensitivity of possible
experiments. Backgrounds that may be relevant are discussed. Theoretically
interesting models can be probed with existing technologies, and may even be
within reach using ongoing direct detection experiments. Significant
improvements in sensitivity should be possible with dedicated experiments,
opening up a window to new regions in dark matter parameter space.Comment: 9 pages. Updated figure and references. Freeze-in region corrected.
Other minor clarification
Direct Detection of sub-GeV Dark Matter with Semiconductor Targets
Dark matter in the sub-GeV mass range is a theoretically motivated but
largely unexplored paradigm. Such light masses are out of reach for
conventional nuclear recoil direct detection experiments, but may be detected
through the small ionization signals caused by dark matter-electron scattering.
Semiconductors are well-studied and are particularly promising target materials
because their band gaps allow for ionization signals from
dark matter as light as a few hundred keV. Current direct detection
technologies are being adapted for dark matter-electron scattering. In this
paper, we provide the theoretical calculations for dark matter-electron
scattering rate in semiconductors, overcoming several complications that stem
from the many-body nature of the problem. We use density functional theory to
numerically calculate the rates for dark matter-electron scattering in silicon
and germanium, and estimate the sensitivity for upcoming experiments such as
DAMIC and SuperCDMS. We find that the reach for these upcoming experiments has
the potential to be orders of magnitude beyond current direct detection
constraints and that sub-GeV dark matter has a sizable modulation signal. We
also give the first direct detection limits on sub-GeV dark matter from its
scattering off electrons in a semiconductor target (silicon) based on published
results from DAMIC. We make available publicly our code, QEdark, with which we
calculate our results. Our results can be used by experimental collaborations
to calculate their own sensitivities based on their specific setup. The
searches we propose will probe vast new regions of unexplored dark matter model
and parameter space.Comment: 30 pages + 22 pages appendices/references, 17 figures, website at
http://ddldm.physics.sunysb.edu/, v2 added references, minor edits to text
and Figs. 2 and 14, version to appear in JHE
First Direct Detection Limits on sub-GeV Dark Matter from XENON10
The first direct detection limits on dark matter in the MeV to GeV mass range
are presented, using XENON10 data. Such light dark matter can scatter with
electrons, causing ionization of atoms in a detector target material and
leading to single- or few-electron events. We use 15 kg-days of data acquired
in 2006 to set limits on the dark-matter-electron scattering cross section. The
strongest bound is obtained at 100 MeV where sigma_e < 3 x 10^{-38} cm^2 at 90%
CL, while dark matter masses between 20 MeV and 1 GeV are bounded by sigma_e <
10^{-37} cm^2 at 90% CL. This analysis provides a first proof-of-principle that
direct detection experiments can be sensitive to dark matter candidates with
masses well below the GeV scale.Comment: Submitted to PR