About 80 % of the universe’s mass is believed to include darkish matter. And but, little is understood concerning the composition and construction of the particles that make up darkish matter, presenting physicists with some elementary questions. To discover this elusive matter, researchers try to seize photons, or gentle particles, that are produced when darkish matter particles collide with the seen matter we’re accustomed to.
Most experiments up to now have targeted on darkish matter particles with lots that roughly overlap with these of identified elementary particles. If the particles are lighter than an electron, nonetheless, it’s unlikely they might be detectable with the present commonplace, specifically detectors primarily based on liquid xenon. To this point, no experiment has succeeded in straight detecting darkish matter. But this in itself is a crucial discovering, because it reveals that darkish matter particles don’t exist throughout the mass vary and interplay power examined.
New machine delicate to lower-energy occasions
A world group led by Laura Baudis, Titus Neupert, Björn Penning and Andreas Schilling from UZH’s Division of Physics has now been in a position to probe the existence of darkish matter particles throughout a large mass vary under one mega electron volt (MeV). Utilizing 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 darkish matter particles are extremely unlikely to exist. “That is the primary time we have been in a position to seek for darkish matter particles in such a low mass vary, made attainable by a brand new detector expertise,” says first creator Laura Baudis.
In a 2022 proof of idea, the researchers had examined the primary SNSPD machine that is extremely delicate to lower-energy photons. When a photon strikes the nanowire, it heats it up barely and causes it to immediately lose its superconductivity. The wire briefly turns into a daily conductor, and the ensuing improve in electrical resistance will be measured.
Detecting smallest darkish matter particles
For his or her newest experiment, the UZH scientists optimized their SNSPD for darkish matter detection. Particularly, they outfitted it with superconducting microwires as an alternative of nanowires to maximise its cross part. Additionally they gave it a skinny, planar geometry that makes it extremely delicate to modifications in path. Scientists assume that the Earth passes by means of a “wind” of darkish matter particles, and the particle’s path subsequently shifts over the course of the yr relying on relative velocity. A tool able to choosing up directional modifications will help to filter out non-dark-matter occasions.
“Additional technological enhancements to the SNSPD may allow us to detect alerts from darkish matter particles with even smaller lots. We additionally wish to deploy the system underground, the place it is going to be higher shielded from different sources of radiation,” Titus Neupert says. Under the mass vary of electrons, present fashions to explain darkish matter face appreciable astrophysical and cosmological constraints.
