Dark Matter Wind May Finally Be Detectable with New Superconducting Tech

About 80 percent of the universe’s mass is believed to be dark matter, yet the makeup and organization of its particles remain largely unknown, leaving physicists with fundamental questions. To investigate this elusive material, scientists are working to detect photons, or light particles, that can be produced when dark matter particles collide with the ordinary matter we know, the journal Physical Review Letters reported.

Up to now, most searches have targeted dark matter with masses comparable to familiar elementary particles. If the particles are lighter than an electron, the leading instruments in use today, which rely on liquid xenon, are unlikely to register them.

No experiment has directly observed dark matter so far. This absence still matters, since it rules out dark matter particles within the specific mass range and interaction strengths already tested.

An international team led by Laura Baudis, Titus Neupert, Björn Penning, and Andreas Schilling from UZH’s Department of Physics has now been able to probe the existence of dark matter particles across a wide mass range below one mega electron volt (MeV). Using an improved superconducting nanowire single-photon detector (SNSPD), the researchers reached a sensitivity threshold of about one-tenth the mass of an electron, above which dark matter particles are highly unlikely to exist.

“This is the first time we’ve been able to search for dark matter particles in such a low mass range, made possible by a new detector technology,” says first author Laura Baudis.

In a 2022 proof of concept, the researchers had tested the first SNSPD device that’s highly sensitive to lower-energy photons. When a photon strikes the nanowire, it heats it up slightly and causes it to instantly lose its superconductivity. The wire briefly becomes a regular conductor, and the resulting increase in electrical resistance can be measured.

For their latest experiment, the UZH scientists optimized their SNSPD for dark matter detection. In particular, they equipped it with superconducting microwires instead of nanowires to maximize its cross-section. They also gave it a thin, planar geometry that makes it highly sensitive to changes in direction.

Scientists assume that the Earth passes through a “wind” of dark matter particles, and the particle’s direction therefore shifts over the course of the year depending on relative velocity. A device capable of picking up directional changes can help to filter out non-dark-matter events.

“Further technological improvements to the SNSPD could enable us to detect signals from dark matter particles with even smaller masses. We also want to deploy the system underground, where it will be better shielded from other sources of radiation,” Titus Neupert says.

Below the mass range of electrons, current models to describe dark matter face considerable astrophysical and cosmological constraints.

4155/v