Axions, like dark matter, are out there somewhere

Scientists have found no evidence of the hypothetical particle axion in the first run of the ABRACADABRA experiment, which took place last year in months of July and August.

Scientists in recent years have been trying to discover the particles that make up dark matter - the mysterious form of matter believed to account for about 85 per cent of the total mass in the known universe.

Axions are thought to be one of the particles that make up dark matter. Scientists expect them to be among the lightest particles in the universe. Their discovery would almost certainly lead to the modification of the principles of electromagnetism at a minute level, and also have an impact on the theory of the formation of galaxies and expansion of the universe.

In the current study, a team of physicists from the Massachusetts Institute of Technology (MIT) and a number of other institutions designed a doughnut-shaped apparatus to detect elusive axions.

Scientists believe that if axions really exist, they may be detected by looking at "magnetars" - special type of neutron stars that generate very intense magnetic fields in the universe.

In presence of such powerful magnetic fields, axions should be converted into radio waves, which can be easily detected by special instruments on Earth.

The new ABRACADABRA experiment (A Broadband/Resonant Approach to Cosmic Axion Detection with an Amplifying B-field Ring Apparatus) is made up of doughnut-shaped device, which is suspended in a freezer to avoid noise produced in the surroundings.

According to the research team, if axions really exist, a detector should sense a magnetic field in the middle of the doughnut. However, it is a challenging experiment as the expected signal will be very minute, less than 20 atto-Tesla.

In the first run of the experiment, scientists found no evidence of the elusive particle within the mass range of 0.31 to 8.3 nanoelectronvolts (equivalent to approximately one-quintillionth the mass of a proton).

These results suggest that axions either don't exist or they produce even smaller effect on electricity and magnetism, which the current apparatus failed to detect.

The team plans to continue running the experiment to detect even smaller and weaker axions.

"We're excited that we can now say, 'We have a way to look here, and we know how to do better!'," said Lindley Winslow, principal investigator of the study and an assistant professor at MIT.

The findings of the study were published in the journal Physical Review D.

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