22 January 2022
Axions are a preferred candidate within the seek for darkish matter. There have been earlier searches for these hypothetical particles, all of which have provide you with nothing. However not too long ago the outcomes of a brand new seek for darkish matter axions have been revealed…and has additionally discovered nothing. Nonetheless, the research is attention-grabbing due to the character and scale of the search.
Axions are a kind of hypothetical particle first proposed within the Nineteen Seventies. They weren’t proposed to unravel darkish matter, however relatively to deal with sure features of the idea of quantum chromodynamics, which describes the sturdy nuclear pressure. In keeping with the theories, could be low mass, chargeless particles that don’t work together strongly with gentle. Sounds a bit like darkish matter, doesn’t it?
If axions do comprise darkish matter, then one of many extra refined results is that their quantum area would have topological defects. Principally, the axions would are inclined to cluster into oriented areas on scales smaller than a galaxy, however bigger than Earth. It’s just like the way in which unmagnetized iron accommodates crystals, the place every crystal has its personal magnetic orientation. For the reason that crystals are randomly oriented, on a big scale the general magnetic area of the iron averages to zero. However on a small scale, there are domains with a uniform magnetic area, with area partitions between every area.
This new research makes an attempt to measure an axion area utilizing the World Community of Optical Magnetometers for Unique Physics Searches (GNOME). It’s a community of 14 delicate magnetometers in labs all around the world. 9 of them have been used on this specific research. The experiment concerned utilizing laser gentle to magnetically align a group of atoms. If a darkish matter axion have been to work together with the atoms, it could trigger the magnetic area of the atoms to shift barely, which the magnetometer might detect. This type of small perturbation occurs randomly on a regular basis with atoms, however since an axion area area is bigger than Earth, axions at each lab ought to tweak atoms in the identical means. What’s extra, if Earth occurred to go from one axion area to a different, the axion perturbation ought to shift in the identical means all throughout the globe.
The workforce gathered a month of steady knowledge and ran statistical correlations between labs. What they discovered was a wash. The atomic perturbations have been indistinguishable from random noise. That doesn’t imply the experiment was a failure. The experiment locations sure constraints on the doable mass of axions. Any concept proposing axion darkish matter can’t have axion particles on this vary. The workforce is transferring ahead with extra delicate research that may both uncover axions or additional constrain them.
At this level, the seek for darkish matter appears to repeat the identical story. Search for a selected kind of darkish matter particle and fail to search out them. However usually that’s the way in which science works. We love tales of the eureka second, the place a superb discovery modifications the world. However usually science is extra of an excavation, the place failed hypotheses are scraped fastidiously away till what stays is the reality.
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