References and Links
Abstract
Any stable, weakly interacting massive particle (WIMP) provides a natural
candidate for dark matter. Perhaps the best motivated candidate
is the neutralino, the lightest stable supersymmetric particle. If neutralinos
comprise the dark matter and are sufficiently concentrated near the center of
our galaxy, then direct annihilation to gamma-rays should result in a
nearly monoenergetic gamma-ray line at Egamma =
mX with a sufficient intensity to be observed with future
atmospheric Cherenkov detectors. Central cusps in the density
distributions of dark-matter halos are predicted by recent N-body
simulations of hierarchical structure formation. We have been funded by DOE
to begin observations of the galactic center with the new high resolution
Granite III camera on the Whipple 10 meter telescope, and to explore new
technological developments required to reduce the energy threshold of the
Whipple 10 m telescope. Development on new electronics (including FADCs)
and high quantum efficiency detectors. Such a reduction in threshold can
be "traded" for a larger effective area using the "large zenith angle
technique." Whipple atmospheric Cherenkov
telescope is located in the
northern hemisphere it can only observe the galactic center at large
zenith angles (> 60 degrees). While this results in a substantial increase
in the effective area (to as much as 0.3 km2), it also will result
in a substantial increase in the energy threshold. The flux and spectrum
of secondary gamma-rays for a centrally cusped halo is in rough agreement
with that of the peculiar GeV gamma-ray source observed by the EGRET satellite
experiment at the galactic center. Observation of the
annihilation line, however, would produce a signature for dark matter
which could not easily be produced by any other known astrophysical
process. Cosmological constraints and experimental limits restrict the
allowed supersymmetric parameter space, and require neutralino masses
in the range 30 GeV< mX < 3 TeV. VLPCs are state of the art
high quantum efficiency cryogenically cooled solid state detectors adapted
to High Energy Particle experiments (
CDF at Fermilab).
High Quantum Efficiency Detector
We are currently researching whether VLPCs developed and manufactured by Rockwell International (now Boeing) can act as the camera pixels for a high quantum efficiency detector. See the table for the properties of the VLPC. In parallel with this effort we have been funded by NASA to develop high quantum efficiency (room temperature) detectors using a new type of solid state photocathode.
hbar.wustl.edu>