MODERN COSMOLOGY

Innovative techniques based on phonon-mediated devices 277

Figure 8.2.Discrimination capability of the CRESST test detector.

In this exposition, the collected statistics correspond toMdetT= 1 .6kgday.

After the background rejection, only four events survive as slow nuclear

recoils.

• Twelve month exposure in 1999, providing 96 live days collected withfour
  165 g Ge detectorsoperated with a Ge ST phonon readout (see previous
  section). In this exposition, the collected statistics correspond toMdetT=
  10 .6 kg day. After the background rejection, only 17 events survive as slow
  nuclear recoils. The four Ge detectors are tightly packed in order to increase
  the neutron multiple scattering probability. Since four recoil events were cut
  as in coincidence between two detectors (of course the probability of WIMP
  double scattering is completely negligible), only 13 recoil events attributable
  to WIMPs survive. (In figure 8.3 the nuclear recoil events are represented by
  circled points.)

The 13-nuclear-recoil energy spectrum is compatible with the expected
WIMP-caused spectrum as deduced by the DAMA neutralino parameters.
However, the CDMS collaboration claims that there is clear evidence that these
13 single events are caused by background neutrons. In fact, the background