How to Hear the Faintest Signal express

Original: "Sensitivity enhancement techniques for cryogenic calorimeters in the NUCLEUS experiment"
arXiv:2603.28276 · 2026-03-30 · CC BY 4.0 · 1 min
Detectors designed to hunt elusive particles have been taught to hear signals twice as quiet as before.

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A detector that hunts for rare particles is like an ear trying to catch a whisper in a noisy room. The quieter the signal, the harder it is to tell apart from random noise. In the NUCLEUS experiment, such detectors, cryogenic calorimeters, are cooled to near absolute zero so they can pick up even a faint pulse of heat from a single particle.

To sharpen the instrument's hearing, the scientists used two tricks. First, they swept through many settings and found the one where the signal comes through most clearly. Then they combined readings from two different channels of the same detector, as if listening to a conversation with both ears instead of one. Processing the two signals together helps filter out noise and spot quieter events.

As a result, the sensitivity threshold dropped to 2.94 electronvolts. For comparison, the energy of a single photon of visible light is about 2 electronvolts.

Such a low threshold is a record for detectors based on calcium tungstate. This means that the upcoming NUCLEUS run will be able to search for particles that were previously lost in the noise. Among them, there may be traces of dark matter — the invisible substance that makes up most of the universe.

The cryogenic detector operates at temperatures below -270°C — colder than the surface of Pluto.

Scientists
Niels BohrPascual JordanWerner HeisenbergFritz ZwickyVera RubinRoberto D. Peccei
Concepts
cryogenic sensing cryogenic temperature quantum sensing enhancement tes ultra sensitive sensor quantum detector power consumption cryostat cls method sensitivity threshold noise reduction spectroscopy matched filter sensitivity threshold calorimeter quantum noise reduction gravitational wave detector noise reduction accelerometer neutron detection techniques signal averaging