Enriched TeO2 bolometers with active particle discrimination: Towards the CUPID experiment

• Published in: Physics letters. B Vol. 767; no. C; pp. 321 - 329
• Main Authors: Artusa, D.R., Avignone, F.T., Beeman, J.W., Dafinei, I., Dumoulin, L., Ge, Z., Giuliani, A., Gotti, C., de Marcillac, P., Marnieros, S., Nagorny, S., Nisi, S., Nones, C., Norman, E.B., Novati, V., Olivieri, E., Orlandi, D., Pagnanini, L., Pattavina, L., Pessina, G., Pirro, S., Poda, D.V., Rusconi, C., Schäffner, K., Scielzo, N.D., Zhu, Y.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 10.04.2017; Elsevier
• Subjects: Bolometers; Cherenkov emission; Double beta decay; INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; Isotope enrichment; MATERIALS SCIENCE; Neganov-Luke effect; NUCLEAR PHYSICS AND RADIATION PHYSICS; Isotope enrichment; Bolometers; Neganov–Luke effect; Double beta decay; Cherenkov emission
• ISSN: 0370-2693; 1873-2445
• DOI: 10.1016/j.physletb.2017.02.011

We present the performances of two 92% enriched 130TeO2 crystals operated as thermal bolometers in view of a next generation experiment to search for neutrinoless double beta decay of 130Te. The crystals, 435 g each, show an energy resolution, evaluated at the 2615 keV γ-line of 208Tl, of 6.5 and 4.3 keV FWHM. The only observable internal radioactive contamination arises from 238U (15 and 8 μBq/kg, respectively). The internal activity of the most problematic nuclei for neutrinoless double beta decay, 226Ra and 228Th, are both evaluated as <3.1 μBq/kg for one crystal and <2.3 μBq/kg for the second. Thanks to the readout of the weak Cherenkov light emitted by β/γ particles by means of Neganov–Luke bolometric light detectors we were able to perform an event-by-event identification of β/γ events with a 95% acceptance level, while establishing a rejection factor of 98.21% and 99.99% for α particles.