# Gram-scale cryogenic calorimeters for rare-event searches

## TL;DR

This paper explores how reducing the size of cryogenic calorimeters to the gram scale can significantly lower their energy thresholds, enabling detection of rare events like MeV dark matter and neutrino interactions, with a prototype achieving a record low threshold.

## Contribution

It presents a scaling law for energy thresholds versus detector size and demonstrates a gram-scale calorimeter reaching a record low threshold of about 20 eV.

## Key findings

- Achieved a 19.7 eV energy threshold with a 0.5 g Al₂O₃ calorimeter.
- Established a scaling law relating detector size to energy threshold.
- Demonstrated potential for gram-scale cryogenic calorimeters in rare-event detection.

## Abstract

The energy threshold of a cryogenic calorimeter can be lowered by reducing its size. This is of importance since the resulting increase in signal rate enables new approaches in rare-event searches, including the detection of MeV mass dark matter and coherent scattering of reactor or solar neutrinos. A scaling law for energy threshold vs. detector size is given. We analyze the possibility of lowering the threshold of a gram-scale cryogenic calorimeter to the few eV regime. A prototype 0.5 g Al$_2$O$_3$ device achieved an energy threshold of (${19.7\pm0.1}$) eV, the lowest value reported for a macroscopic calorimeter.