1. Development of large-volume $^{130}$TeO$_2$ bolometers for the CROSS $2\beta$ decay search experiment
- Author
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Avignone III, F. T., Barabash, A. S., Berest, V., Bergé, L., Calvo-Mozota, J. M., Carniti, P., Chapellier, M., Dafinei, I., Danevich, F. A., Dumoulin, L., Ferella, F., Ferri, F., Gallas, A., Giuliani, A., Gotti, C., Gras, P., Ianni, A., Imbert, L., Khalife, H., Kobychev, V. V., Konovalov, S. I., Loaiza, P., de Marcillac, P., Marnieros, S., Marrache-Kikuchi, C. A., Martinez, M., Nisi, S., Nones, C., Olivieri, E., de Solórzano, A. Ortiz, Peinaud, Y., Pessina, G., Poda, D. V., Rosier, Ph., Scarpaci, J. A., Tretyak, V. I., Umatov, V. I., Zarytskyy, M. M., and Zolotarova, A.
- Subjects
Physics - Instrumentation and Detectors ,Nuclear Experiment - Abstract
We report on the development of thermal detectors based on large-size tellurium dioxide crystals (45x45x45 mm), containing tellurium enriched in $^{130}$Te to about 91%, for the CROSS double-beta decay experiment. A powder used for the crystals growth was additionally purified by the directional solidification method, resulting in the reduction of the concentration of impurities by a factor 10, to a few ppm of the total concentration of residual elements (the main impurity is Fe). The purest part of the ingot (the first ~200 mm, about 80% of the total length of the cylindrical part of the ingot) was determined by scanning segregation profiles of impurities and used for the $^{130}$TeO$_2$ powder production with no evidence of re-contamination. The crystal growth was verified with precursors produced from powder with natural Te isotopic composition, and two small-size (20x20x10 mm) samples were tested at a sea-level laboratory showing high bolometric and spectrometric performance together with acceptable $^{210}$Po content (below 10 mBq/kg). This growth method was then applied for the production of six large cubic $^{130}$TeO$_2$ crystals and 4 of them were taken randomly to be characterized at the Canfranc underground laboratory, in the CROSS-dedicated low-background cryogenic facility. Two $^{130}$TeO$_2$ samples were coated with a thin, $O$(100 nm), metal film in form of Al layer (on 4 sides) or AlPd grid (on a single side) to investigate the possibility to tag surface events by pulse-shape discrimination. Similarly to the small natural precursors, large-volume $^{130}$TeO$_2$ bolometers show high performance and even better internal purity ($^{210}$Po activity $\sim$ 1 mBq/kg, while activities of $^{228}$Th and $^{226}$Ra are below 0.01 mBq/kg), satisfying requirements for the CROSS and, potentially, next-generation experiments., Comment: Submitted to JINST; 22 pages, 11 figures, 4 tables
- Published
- 2024