Speaker
Description
Next generation $^{100}$Mo based neutrinoless double beta decay searches like AMoRE and CUPID require a precise understanding of the detector response of cryogenic $^{100}$Mo based detectors at the Q-value (3034 keV) of the $0\nu\beta\beta$ decay. However, common long-lived calibration sources like $^{208}$Tl provide the last intense calibration peaks at or below 2.6 MeV and hence require an extrapolation to the region of interest (ROI). In the CUPID-Mo demonstrator we operated 20 enriched Li$_2$MoO$_4$ detector modules at ~20 mK for an extended period of more than 1 year proving the competitiveness of this detector tenchnology for future $0\nu\beta\beta$ searches. We also performed a dedicated ~3 week calibration campaign with a specially irradiated $^{56}$Co source to directly assess the detector response with high energy $\gamma$ lines at and above the $^{100}$Mo Q-Value. In this contribution we will present results of this calibration campaign with respect to a typical detector response extrapolation in terms of energy bias and energy resolution broadening at the Q-value of $^{100}$Mo. In addition, the rich $\gamma$ spectrum of the $^{56}$Co source allowed for an assessment of the detector response for different event topologies in particular of well localised electron-positron pair creation events with escape of the two 511 keV $\gamma$'s versus multi-site events like typical Compton + Photoabsorption events for full energy peaks in the few MeV range. We observe a small but statistically significant shift of ~0.6 keV in the energy reconstruction of these event types, which if confirmed should be considered as systematic for the $0\nu\beta\beta$ ROI.
| Collaboration you are representing | CUPID-Mo |
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