U.Chicago Physics 335 - CDMS: Cryogenic Dark Matter Search
Cryogenic Dark Matter Search with a State-of-the-Art Particle Detector
The UltraLo-1800 alpha particle counter is a prototype, table-top,
particle detector that measures alpha particle emissivities at levels
below 0.005 alphas/cm^2-hr. These sensitivities are necessary for
characterizing the radioactivity of materials that will be used in
the next phase of the Cryogenic Dark Matter Search (CDMS). The
particle counter was designed and patented by a commercial company
(XIA). It is a large electrode, ionization chamber. Rejection of
ambient gamma and beta particles is achieved through a combination of
clever geometric design and the inherent properties of particle
propagation through a gas. Alpha particles are identified on an
event-by-event basis after analyzing the shapes of the measured
pulses. For the past year, CDMS has worked closely with this company
to improve the design and performance of the XIA counter.
We plan to continue this work and to set up a series of material
screening studies to systematically characterize materials that are
used in the fabrication of the CDMS ZIP (z-senstive ionization and
phonon) detectors. An efficient and productive screening program
with this detector also has applications to other dark matter
searches. Such experiments share similar problems from radioactive
contamination of materials used to construct the dark matter
detectors. Outside of particle physics, the XIA detector has
applications towards semi-conductor fabrication.
Supervisors: Young-Kee Kim, Dan Bauer(Fermilab Scientist)