A Textured Silicon Calorimetric Light Detector

We apply the standard photovoltaic technique of texturing to reduce the reflectivity of silicon cryogenic calorimetric light detectors. In the case of photons with random incidence angles, absorption is compatible with the increase in surface area. For the geometrically thin detectors studied, energy resolution from athermal phonons, dominated by position dependence, is proportional to the surface-to-volume ratio. With the CaWO4 scintillating crystal used as light source, the time constants of the calorimeter should be adapted to the relatively slow light-emission times.Comment: Submitted to Journal of Applied Physic

Discrimination between Nuclear Recoils and Electron Recoils by Simultaneous Detection of Phonons and Scintillation Light

We have developed a detector, consisting of a cryogenic calorimeter with a scintillating crystal as absorber, and a second calorimeter for the detection of the scintillation light, both operated at 12 mK. Using a CaWO4 crystal with a mass of 6g as scintillating absorber, we have achieved a discrimination of nuclear recoils against electron recoils with a suppression factor of 99.7% at energies above 15 keV. This novel method will be applied for background rejection in the CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) experiment looking for dark matter Weakly Interacting Massive Particles (WIMPs).Comment: 10 pages, 4 zipped figures (not good res.

The CRESST Dark Matter Search

The current status of CRESST (Cryogenic Rare Event Search using Superconducting Thermometers) and new results concerning the detector development are presented. The basic technique of CRESST is to search for particle Dark Matter (WIMPS, Weakly Interacting Massive particles) by the measurement of non-thermal phonons as created by WIMP-induced nuclear recoils. Combined with the newly developed method of simultaneous measurement of scintillation light, strong background discrimination is possible, resulting in a substantial increase in WIMP detection sensitivity. The short and long term perspectives of CRESST are discussed.Comment: 12 pages, 6 figure

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.Comment: To appear in the proceedings of the CAPP2000 Conference, Verbier, Switzerland, July, 2000 (eds J. Garcia-Bellido, R. Durrer, and M. Shaposhnikov

CRESST Dark Matter Search

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Imaging cryogenic detectors for astro and particle physics

In this thesis a new detector concept for a cryogenic imaging spectrometer has been experimentally developed. The new detector scheme consists of a large dielectric absorber (sapphire), which is simultaneously read out with two superconducting phase transition thermometers (SPTs). An X-ray absorbed in the sapphire creates a non-equilibrium phonon flux. Each thermometer detects a share of the initially deposited energy. The measurement of the coincident signals allows the reconstruction of both the energy and the position of the X-ray event. With a prototype detector an energy resolution of 224 eV (#+-# 6 keV) with imaging over a length of 1 cm was demonstrated. The spatial resolution was determined to be better than #approx#200 #mu#m. In addition, with a single SPT an energy resolution of 27.6 eV (#+-# 1.5 keV) was shown, which indicates the potential of such a detector. Further investigations showed the ability to extend this concept to larger areas, higher count rates (>#approx#kHz) and better energy and position resolution. (author)SIGLEAvailable from British Library Document Supply Centre-DSC:D207929 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Imaging X-ray spectroscopy with superconducting phase transition thermometers

We report on the development of an imaging cryogenic X-ray spectrometer based upon X-ray absorption in sapphire and readout by two tungsten superconducting phase transition thermometers (SPTs). We achieve one-dimensional imaging over an absorber length of 10 mm with a position resolution of approximate to 200 mu m. (C) 2000 Elsevier Science B.V. All rights reserved

Superconducting phase transition thermometers for X-ray spectroscopy

We report on a first attempt on a cryogenic imaging spectrometer based on sapphire absorber and two superconducting phase transition thermometers. One-dimensional imaging was achieved over a length of 10 mm with a spatial resolution of approximate to 200 mu m and an energy resolution of 216 eV for 5.89 keV X-rays. (C) 2000 Elsevier Science B.V. All rights reserved