Electron and Gamma Background in CRESST Detectors

R.F. Lang , G. Angloher , M. Bauer , I. Bavykina , A. Bento , A. Brown , C. Bucci , C. Ciemniak , C. Coppi , G. Deuter , F. von Feilitzsch , D. Hauff , S. Henry , P. Huff , J. Imber , S. Ingleby , C. Isaila , J. Jochum , M. Kiefer , M. Kimmerle , H. Kraus , J.-C. Lanfranchi , B. Majorovits , M. Malek , R. Mcgowan , V.B. Mikhailik , E. Pantic , F. Petricca , S. Pfister , W. Potzel , F. Pröbst , S. Roth , K. Rottler , C. Sailer , K. Schäffner , J. Schmaler , S. Scholl , W. Seidel , L. Stodolsky , A.J.B. Tolhurst , I. Usherov , W. Westphal

The CRESST experiment monitors 300 g CaWO crystals as targets for particle interactions in an ultra low background environment. In this paper, we analyze the background spectra that are recorded by three detectors over many weeks of data taking. Understanding these spectra is mandatory if one wants to further reduce the background level, and allows us to cross-check the calibration of the detectors. We identify a variety of sources, such as intrinsic contaminations due to primordial radioisotopes and cosmogenic activation of the target material. In particular, we detect a 3.6 keV X-ray line from the decay of Ca with an activity of (26±4) μBq, corresponding to a ratio Ca/Ca=(2.2±0.3)×10.

Mots clés: CRESST; CaWO; Low Background; Calcium-41; Dark Matter; 29.40.Vj; 95.35.+d

R.F. Lang, G. Angloher, M. Bauer, I. Bavykina, A. Bento, et al.. Electron and Gamma Background in CRESST Detectors. Astroparticle Physics, 2009, 32 (6), pp.318. ⟨10.1016/j.astropartphys.2009.09.009⟩. ⟨hal-00510616⟩