Optimal Particle identification Of Single Site events with Underground MKIDs detectors

The observation of neutrinoless double-beta decay (0) would revolutionise our understanding of neutrinos by affirming their Majorana nature and shedding light on their absolute mass scale and hierarchy. Detecting its monochromatic peak at MeV levels, with half-lives over 1026-years, is a significant challenge.

Scientists are striving to push the scale of experimental exposures to tons of material per years.

It is only in a background-free experiment that sensitivity scales linearly with exposure, maximising the benefits of increased detector mass.

The forefront of this search lies with ton-scale arrays of bolometers at mK temperatures, such as CUORE, which investigates 0 in 130Te using TeO2 crystals, known for their exceptional energy resolution but plagued by background event identification challenges.

With its 34% isotopic abundance 130Te emerges as the leading 0 candidate, bypassing the need for the now-challenged enrichment process.

OPOSSUM will revolutionise event detection by outfitting 12 CUORE-crystals with six quantum limited sensors (Microwave Kinetic Inductance Detectors) and a thermistor. This innovative approach will enable discrimination of events by classifying them as Single Site or Multi Site Events. Through pulse-shape analysis, OPOSSUM is set to tag 0 signals with 3 distinction from any background.

This method has the potential to lower CUORE's background from 10-2 to below 10-4 counts/keV/kg/year.

The success of OPOSSUM will facilitate rapid deployment within the existing setup without extensive R&D or major financial outlay.

OPOSSUM-1ton is poised to become the first bolometric ton-scale, background-free experiment that can aim at surpassing the inverted hierarchy scenario, i.e. <10 meV Majorana mass.My vast experimental knowledge in low-temperature detectors is crucial for OPOSSUM's mission to push the boundaries of particle physics as per the EU Astroparticle committee recommendation for the neutrino physics programme.