Science: With Light Through the Wall: Desi Investigates Dark Matter

Sciences With Light Through the Wall: Dicey’s Search for Dark Matter

An employee of Germany’s Electron Synchrotron (DESY) passes through the ALPS II. picture

© Ulrich Perrey / dpa / archive image

Dark matter could be up to five times more abundant in the universe than normal matter. Until now, scientists know very little about it. An experiment has now begun at the Desy Research Center in Hamburg that could shed light on this question.

With a very sensitive experiment, the research team wants to look for particularly light particles that could make up the mysterious dark matter. The “Alps II” project began on Tuesday, as announced by Germany’s Electron Synchrotron (Desy) in Hamburg. What they are looking for are so-called axions or axon-like particles, which are said to interact so weakly with known matter that they cannot be found in accelerator experiments.

In the front half of the 250-meter “alpine” facility, particles of light (photons) are kept in a magnetic field with the help of mirrors. The back area is separated by a photoresist wall. The detector should indicate if the photon should appear there. According to the researchers, the discovery of such a light particle behind the light-tight wall would prove the existence of axions. A photon can only penetrate a wall if it is temporarily converted into such an extremely light particle.

Because of the experimental setup, the researchers also named the project the “Light Through the Wall Experiment.” “For all our technical tricks, the probability that a photon will turn into an axion and back again is very small – comparable to rolling 33 dice at the same time,” said Axel Lindner, researcher at DISSEY, project manager and spokesperson for Alps. cooperation.

The facility, which took a decade to build, offers a number of superlatives: According to Desy, the light detector is so sensitive it can detect one light particle per day. The accuracy of the mirror system for light also broke the record: “The distance between the mirrors may not differ with respect to the wavelength of the laser light by more than a fraction of the atomic diameter.” For the experiment, 24 large superconducting magnets were cooled to minus 269 degrees.

Daisy expects to publish the first results from measurements of the “Alps” in 2024. The Max Planck Institute for Gravitational Physics, the Institute for Gravitational Physics of the Leibniz University in Hannover and Cardiff University (Great Britain) are also involved.

Axions – if they really exist – could be the building blocks of the mysterious dark matter, which according to current calculations occurs in the universe at a rate five times more than normal, visible matter.

Max Planck Institute for Physics Alps II Experiment Search Youtube Desy Axion Animation Video About Dark Matter and Alps


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