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arXiv · 1410.1753

A detector module with highly efficient surface-alpha event rejection operated in CRESST-II Phase 2

R. Strauss·G. Angloher·A. Bento·C. Bucci·L. Canonica·A. Erb·F. v. Feilitzsch·N. Ferreiro·P. Gorla·A. Gütlein·D. Hauff·J. Jochum·M. Kiefer·H. Kluck·H. Kraus·J. -C. Lanfranchi·J. Loebell·A. Münster·F. Petricca·W. Potzel·F. Pröbst·F. Reindl·S. Roth·K. Rottler·C. Sailer·K. Schäffner·J. Schieck·S. Scholl·S. Schönert·W. Seidel·M. v. Sivers·M. Stanger·L. Stodolsky·C. Strandhagen·A. Tanzke·M. Uffinger·A. Ulrich·I. Usherov·S. Wawoczny·M. Willers·M. Wüstrich·A. Zöller
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Abstract

The cryogenic dark matter experiment CRESST-II aims at the direct detection of WIMPs via elastic scattering off nuclei in scintillating CaWO$_4$ crystals. We present a new, highly improved, detector design installed in the current run of CRESST-II Phase 2 with an efficient active rejection of surface-alpha backgrounds. Using CaWO$_4$ sticks instead of metal clamps to hold the target crystal, a detector housing with fully-scintillating inner surface could be realized. The presented detector (TUM40) provides an excellent threshold of ${\sim}\,0.60\,$keV and a resolution of $σ\,{\approx}\,0.090$ keV (at 2.60$\,$keV). With significantly reduced background levels, TUM40 sets stringent limits on the spin-independent WIMP-nucleon scattering cross section and probes a new region of parameter space for WIMP masses below 3$\,$GeV/c$^2$. In this paper, we discuss the novel detector design and the surface-alpha event rejection in detail.

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R. Strauss, G. Angloher, A. Bento, C. Bucci, L. Canonica, A. Erb, F. v. Feilitzsch, N. Ferreiro, P. Gorla, A. Gütlein, D. Hauff, J. Jochum, M. Kiefer, H. Kluck, H. Kraus, J. -C. Lanfranchi, J. Loebell, A. Münster, F. Petricca, W. Potzel, F. Pröbst, F. Reindl, S. Roth, K. Rottler, C. Sailer, K. Schäffner, J. Schieck, S. Scholl, S. Schönert, W. Seidel, M. v. Sivers, M. Stanger, L. Stodolsky, C. Strandhagen, A. Tanzke, M. Uffinger, A. Ulrich, I. Usherov, S. Wawoczny, M. Willers, M. Wüstrich, A. Zöller. 2016-01-25. A detector module with highly efficient surface-alpha event rejection operated in CRESST-II Phase 2. https://doi.org/10.1140/epjc%2Fs10052-015-3572-9

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