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Results and plans of the CRESST dark matter search

M. Altmann, G. Angloher, M. Bruckmayer, C. Bucci, S. Cooper, C. Cozzini, P. DiStefano, F. von Feilitzsch, T. Frank, D. Hauff, Th. Jagemann, J. Jochum, R. Keeling, H. Kraus, J. Macallister, F. Proebst, Y. Ramachers, J. Schnagl, W. Seidel, I. Sergeyev, M. Stark, L. Stodolsky, H. Wulandari

TL;DR

The paper reports on the CRESST Phase I search for WIMP dark matter using cryogenic sapphire calorimeters, achieving low-threshold, high-resolution nuclear-recoil detection and competitive limits, especially for low-mass WIMPs, and identifies a background from crystal supports. It then outlines Phase II plans to implement scintillating CaWO4 calorimeters to achieve strong electron-recoil discrimination, expanding to ~10 kg of detectors with superior background rejection. The anticipated gains include substantially improved WIMP sensitivities, enabling stringent tests of claimed signals and tighter constraints on spin-independent and spin-dependent interactions. Overall, the work demonstrates both the technical feasibility of large-mass cryogenic detectors in a low-background underground facility and a concrete path toward enhanced dark matter sensitivity.

Abstract

Data taken by CRESST in 2000 with a cryogenic detector system based on 262 g sapphire crystals is used to place limits on WIMP dark matter in the Galactic Halo. The detector is especially sensitive for low-mass WIMPS with spin-dependent cross sections and improves on existing limits in this region. CRESST is now preparing for a second phase, which will use a 10 kg detector consisting of 300 g CaWO4 crystals with simultaneous detection of phonons and scintillation light to reduce background.

Results and plans of the CRESST dark matter search

TL;DR

The paper reports on the CRESST Phase I search for WIMP dark matter using cryogenic sapphire calorimeters, achieving low-threshold, high-resolution nuclear-recoil detection and competitive limits, especially for low-mass WIMPs, and identifies a background from crystal supports. It then outlines Phase II plans to implement scintillating CaWO4 calorimeters to achieve strong electron-recoil discrimination, expanding to ~10 kg of detectors with superior background rejection. The anticipated gains include substantially improved WIMP sensitivities, enabling stringent tests of claimed signals and tighter constraints on spin-independent and spin-dependent interactions. Overall, the work demonstrates both the technical feasibility of large-mass cryogenic detectors in a low-background underground facility and a concrete path toward enhanced dark matter sensitivity.

Abstract

Data taken by CRESST in 2000 with a cryogenic detector system based on 262 g sapphire crystals is used to place limits on WIMP dark matter in the Galactic Halo. The detector is especially sensitive for low-mass WIMPS with spin-dependent cross sections and improves on existing limits in this region. CRESST is now preparing for a second phase, which will use a 10 kg detector consisting of 300 g CaWO4 crystals with simultaneous detection of phonons and scintillation light to reduce background.

Paper Structure

This paper contains 10 sections, 4 equations, 14 figures, 1 table.

Table of Contents

  1. Low-background facility
  2. Detectors and results of Phase I
  3. Sapphire cryogenic calorimeters
  4. Data taken in Gran Sasso
  5. Detector monitoring and calibration
  6. Energy spectrum from dark matter run
  7. Limits on WIMP dark matter
  8. Plans for Phase II
  9. Scintillating calorimeters
  10. Expected dark matter sensitivity

Figures (14)

  • Figure 1: Layout of dilution refrigerator and cold box.
  • Figure 2: Cross section of CRESST building in Hall B. The external shielding is shown in both its open and closed positions.
  • Figure 3: Photograph of a 262 g sapphire detector. The transparent sapphire crystal (4) is in the center. The other visible components are: (1) tungsten thermometer, (2) holder pads with screw contacts for connecting to the heater circuit, (3) plastic springs, (5) sapphire balls, (6) holder pads with screw contacts for connecting to the SQUID read-out circuit.
  • Figure 4: Thermal and electrical connections to thermometer.
  • Figure 6: Typical measured pulse of about 6 keV.
  • ...and 9 more figures