Physicists Build Donut-Shaped Magnet To Find 'Ghost-Like' Dark Matter Particle

An anonymous reader quotes a report from CNET: One of the central puzzles in particle physics is discovering what particle (or particles!) makes up dark matter — the form of matter that is responsible for 85 percent of the mass in the known universe. Some physicists believe searching for a hypothetical particle known as an 'axion' could lead to a better understanding of dark matter and to hunt for it, a team of U.S. physicists have recently designed and tested a basketball-sized, donut-shaped apparatus that can seek it out.

It has been believed that axions may be detectable by looking at an unusual type of neutron star known as a 'magnetar'. These small, erupting stars create some of the most powerful magnetic fields in the universe. Because of their giant magnetic power, axions would be converted to radio waves in the presence of the magnetar -- and thus, detectable by telescopes on Earth. That strange cosmic phenomenon inspired theoretical physicists to create the impressively-named ABRACADABRA experiment (the full name is 'A Broadband/Resonant Approach to Cosmic Axion Detection with an Amplifying B-field Ring Apparatus' so the theorists deserve a round of applause for that backcronym). The experiment consists of a donut (or 'toroid') shaped device, dangled in a freezer just above absolute zero and fine-tuned to create its own magnetic field. If axions exist, the magnetic field in the middle of the donut could reveal them. The study has been published in the journal Physical Review Letters.

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