We present first significant limits on WIMP dark matter by the phonon-light technique, where combined phonon and light signals from a scintillating cryogenic detector are used. Data from early 2004 ...with two 300g CRESST-II prototype detector modules are presented, with a net exposure of 20.5kg days. The modules consist of a CaWO4 scintillating “target” crystal and a smaller cryogenic light detector. The combination of phonon and light signals leads to a strong suppression of non-nuclear recoil backgrounds. Using this information to define an acceptance region for nuclear recoils we have 16 events from the two modules, corresponding to a rate for nuclear recoils between 12 and 40keV of (0.87±0.22) events/(kgday). This is compatible with the rate expected from neutron background, and most of these events lie in the region of the phonon-light plane anticipated for neutron-induced recoils. A particularly strong limit for WIMPs with coherent scattering results from selecting a region of the phonon-light plane corresponding to tungsten recoils, where the best module shows zero events.
Data taken by CRESST with a cryogenic detector system based on 262 g sapphire crystals has been used to place limits on WIMP dark matter in the Galactic Halo. The experiment was especially sensitive ...for low-mass WIMPs with spin-dependent cross sections and improves on existing limits in this region.
At the newly installed neutron scattering facility for the calibration of Dark Matter (DM) detectors we have measured quenching factors (QFs) at room temperature in NE 213 and NaI(Tl). For proton ...energies
E
p
between 1 and 3.5
MeV we found the electron-equivalent energy
E
ee
to obey the relation
E
ee
=
(
0.23
±
0.03
)
E
p
+
(
0.02
±
0.01
)
E
p
2
. The QF of the light output from Na recoils in NaI(Tl) at 850
keV was measured to be
Q
=
0.21
±
0.04
.
A neutron scattering multidetector facility has been designed, set up and put into operation. It is commissioned for the determination of the reduced response of particle detectors where the primary ...interaction leads to a nuclear recoil instead of an electron recoil. Nuclear recoils are investigated by the scattering of a well collimated monoenergetic neutron beam of 11
MeV which is obtained by using an inverse (p,n) reaction. The performance of this facility is discussed.
Cresst-II: dark matter search with scintillating absorbers Angloher, G.; Bucci, C.; Cozzini, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2004, Letnik:
520, Številka:
1-3
Journal Article
Recenzirano
In the CRESST-II experiment, scintillating CaWO4 crystals are used as absorbers for direct weakly interacting massive particles (WIMP) detection. Nuclear recoils can be discriminated against electron ...recoils by measuring phonons and scintillation light simultaneously. The absorber crystal and the silicon light detector are read out by tungsten superconducting phase transition thermometers. Results on the sensitivity of the phonon and the light channel, radiopurity, the scintillation properties of CaWO4, and on the WIMP sensitivity are presented.
The CRESST experiment, aiming at the direct detection of WIMPs via nuclear recoils, is currently using scintillating CaWO4 crystals. The WIMP–nucleus cross section for elastic scattering as well as ...the scintillation efficiency differ considerably for recoils from Ca, W and O in these crystals. Therefore a discriminating detector calibration is essential in order to improve WIMP parameter claims. At the tandem accelerator of the Maier-Leibnitz-Laboratory (MLL) in Garching, Germany, a neutron scattering facility is operated for the determination of the individual quenching factors (QF) in the bulk of a CaWO4 crystal to better understand the detector response to neutron background and a possible WIMP signal. First measurements at room temperature reveal QF(O)=7.8±0.3% (recoil energy 1.0–2.2MeV), QF(Ca)=6.3±1.6% (recoil energy 0.4–1MeV), QF(W)<3.0% (2σ, recoil energy 0.1MeV).
The natural {alpha}-decay of {sup 180}W has been unambiguously detected for the first time. The {alpha} peak is found in a ({gamma}, {beta}, and neutron)-free background spectrum. This has been ...achieved by the simultaneous measurement of phonon and light signals with the CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) cryogenic detectors. A half-life of T{sub 1/2}=(1.8{+-}0.2)x10{sup 18} years and an energy release of Q=2516.4{+-}1.1(stat.){+-}1.2(sys.) keV have been measured. New limits are also set on the half-lives of the other naturally occurring tungsten isotopes.
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