Cosmic Activation of CRESST's CaWO_4 Crystals

Kluck, H.; Angloher, G.; Benato, G.; Bento, A.; Bertolini, A.; Breier, R.; Bucci, C.; Canonica, L.; D' Addabbo, A.; Di Lorenzo, S.; Einfalt, L.; Erb, A.; Feilitzsch, F. v.; Ferreiro Iachellini, N.; Fichtinger, S.; Fuchs, D.; Fuss, A.; Garai, A.; Ghete, V. M.; Gorla, P.; Gupta, S.; Hauff, D.; Ješkovský, M.; Jochum, J.; Kaznacheeva, M.; Kinast, A.; Kraus, H.; Langenkamper, A.; Mancuso, M.; Marini, L.; Mokina, V.; Nilima, A.; Olmi, M.; Ortmann, T; Pagliarone, C. E.; Palušová, V.; Pattavina, L.; Petricca, F.; Potzel, W.; Povinec, P.; Pröbst, F.; Pucci, F.; Reindl, F.; Rothe, J.; Schäffner, K.; Schieck, J.; Schmiedmayer, D.; Schönert, S.; Schwertner, C.; Stahlberg, M.; Stodolsky, L.; Strandhagen, C.; Strauss, R.; Usherov, I.; Wagner, F.; Willers, M.; Zema, V.

doi:10.1088/1742-6596/2156/1/012227

The CRESST experiment searches for dark matter induced nuclear recoils inside CaWO4 based cryogenic calorimeters at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy. To identify reliably a potential signal, a precise understanding of its background budget is crucial. An important background category could be "cosmogenics": radionuclides produced via interactions with cosmic rays, mainly during the crystal production at surface facilities. Albeit CaWO4 is a well-established calorimetric material, no systematic study of its susceptibility for cosmic activation existed so far. In this contribution, we will first report the exposure profile of CRESST's in-house grown TUM93 crystal to cosmic rays. Then we will identify the most prominent cosmogenics via AcTIVIA calculations. Afterwards we discuss the expected background spectrum based on Geant4 simulations and compare it to measurements.