Why do ultra-cold detectors see mysterious low-energy noise?

Cryogenic calorimeters used in dark matter hunts show an unexplained spike in low-energy signals that degrades sensitivity. The authors propose the culprit is thermal stress: when detectors cool from room temperature to operating conditions, the absorber and its underlying sensor layer contract at different rates, creating surface defects that mimic real events. A simple elastic model connects this material-science mechanism to the observed excess, and the team suggests detector redesigns to test and suppress the effect.