J. Schnagl

Limits on WIMP dark matter using sapphire cryogenic detectors

Abstract 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.

High-resolution x-ray spectrometry using iridium–gold phase transition thermometers

Cryogenic detectors based on iridium-gold phase transition thermometers are being developed for various applications in astroparticle physics, aiming at high energy resolution, low energy threshold and moderate count rates. A microcalorimeter with an energy resolution of 15.5 eV (FWHM) for the 55 Mn Kα 1 x-ray line for tentative use in an analytical x-ray system (e.g. SEM, TRFA) is presented.

Results of CRESST phase I

Abstract Results of the CRESST experiment at Gran Sasso using 262 g sapphire calorimeters with tungsten phase transition thermometers are presented. Calibration and analysis methods are described. Data taken in 2000 have been used to place limits on WIMP dark matter particles in the galactic halo. The sapphire detectors are especially sensitive for low-mass WIMPS with spin-dependent interaction and improve on existing limits in this region.

The CRESST dark matter experiment: status and perspectives

Abstract The CRESST experiment in its first phase is using sapphire detectors with tungsten phase transition thermometers to search for dark matter WIMPs. At present four 262 g detectors are performing first measurements under low background conditions. Detector performance as well as preliminary results from the background runs are presented. A second phase of CRESST using CaWO 4 and simultaneous measurement of phonons and scintillation light is in preparation.

The CRESST dark matter search

We discuss the short-and long-term perspectives of the CRESST (Cryogenic Rare Event Search using Superconducting Thermometers) project and present the current status of the experiment and new results concerning detector development. In the search for elementary particle dark matter, CRESST is presently the most advanced deep underground, low-background, cryogenic facility. The basic technique involved is to search for WIMPs (Weakly Interacting Massive Particles) by the measurement of nonthermal phonons, as created by WIMP-induced nuclear recoils. Combined with our newly developed method for the simultaneous measurement of scintillation light, strong background discrimination is possible, resulting in a substantial increase in WIMP detection sensitivity. This will allow a test of the reported positive evidence for a WIMP signal by the DAMA Collaboration in the near future. In the long term, the present CRESST setup permits the installation of a detector mass up to 100 kg. In contrast to other projects, CRESST technology allows the employment of a large variety of detection materials. This offers a powerful tool in establishing a WIMP signal and in investigating WIMP properties in the event of a positive signal.We present the current status of CRESST(Cryogenic Rare Event Search using Superconducting Thermometers) project and new results concerning the development of new detectors based on the simultaneous measurement of phonons and scintillation light. A significant reduction in the background rate could recently be achieved. With our newly developed method for the simultaneous measurement of scintillation light, strong background discrimination is possible also in larger detectors, resulting in a substantial increase in WIMP detection sensitivity.We present the current status of CRESST(Cryogenic Rare Event Search using Superconducting Thermometers) project and new results concerning the development of new detectors based on the simultaneous measurement of phonons and scintillation light. A significant reduction in the background rate could recently be achieved. With our newly developed method for the simultaneous measurement of scintillation light, strong background discrimination is possible also in larger detectors, resulting in a substantial increase in WIMP detection sensitivity.

The CRESST experiment: Recent results and prospects

The CRESST experiment seeks hypothetical WIMP particles that could account for the bulk of dark matter in the Universe. The detectors are cryogenic calorimeters in which WIMPs would scatter elastically on nuclei, releasing phonons. The first phase of the experiment has successfully deployed several 262 g sapphire devices in the Gran Sasso underground laboratories. A main source of background has been identified as microscopic mechanical fracturing of the crystals, and has been eliminated, improving the background rate by up to three orders of magnitude at low energies, leaving a rate close to one count per day per kg and per keV above 10 keV recoil energy. This background now appears to be dominated by radioactivity, and future CRESST scintillating calorimeters which simultaneously measure light and phonons will allow rejection of a great part of it.

Cryogenic detectors } a promising option for GNO?

Abstract An improvement of the statistical and systematic uncertainty beyond the level achieved in GALLEX is an essential prerequisite for GNO. As major contributions to these errors are associated with the detection of the EC-decay of 71 Ge in miniaturized gas counters, low-temperature calorimetric detectors (LTCs) might provide a promising alternative for a later phase of GNO. We report the status of our R&D project on optimization of LTCs for this application.

Dark matter search with CRESST cryogenic detectors

Results of the CRESST experiment at Gran Sasso using 262-g sapphire calorimeters with tungsten phase transition thermometers are presented. Calibration and analysis methods are described. Data taken in 2000 have been used to place limits on WIMP dark matter particles in the Galactic halo. The sapphire detectors are especially sensitive to low-mass WIMPs with spin-dependent interaction and improve on existing limits in this region.

Progress in the development of cryogenic detectors for GNO

Abstract An improvement of the statistical and systematic uncertainty beyond the level achieved in GALLEX is an essential prerequisite for GNO. As major contributions to these errors are associated with the detection of the EC-decay of 71 Ge in miniaturized gas counters, low temperature calorimetric detectors might provide a promising alternative for a later phase of GNO. We report first results achieved in measurements of the EC-decaying isotopes 71 Ge and 37 Ar with cryogenic calorimeters.

Cryogenic microcalorimeters and tunnel junctions for high-resolution energy dispersive x-ray spectrometry

We have been developing cryogenic detectors for astro- particle physics applications including search for Dark Matter, neutrino physics and x-ray astronomy. Most recently we started the development of high resolution x-ray detectors based on superconducting tunnel junctions and superconducting phase transition thermometers/transition edge sensors for microanalysis applications. Both types of sensors are being investigated as well as the cryogenic setup for applications on a scanning electron microscope.