Breakthrough neutrino experiment led by VUB professor

Summary

A team in California, led by a VUB physics professor, has been able to detect a particle trail using radio signals, a first and a promising step in understanding the ever-elusive neutrino

Antarctic lightning

A team of international scientists led by professor Krijn de Vries of the Vrije Universiteit Brussels (VUB), have conducted a sucessful experiment that could be a breakthrough in the detection of a “particle track”. The experiment was significant because it could help in the search for cosmic neutrinos.

Cosmic neutrinos, discovered only 50 years ago, are still a bit of a mystery to scientists. These subatomic particles come from the furthest corners of the universe, are virtually massless and have no electrical charge.

Neutrinos seldom interact with anything else. Very rarely, however, a high-energy neutrino collides with the polar ice. This creates a particle track.

The IceCube Neutrino Observatory, of which the VUB is a member, monitors a cubic kilometre of ice for neutrinos by looking for the light signals emitted during such a collision. But IceCube only detects neutrinos with energies below 10 billion electron volts, which are not high-energy neutrinos.

The kind of neutrinos we will be able to detect will tell us more about the extremely energetic astronomical phenomena in our universe

- Professor Krijn de Vries

To detect neutrinos with higher energies, experiments have been conducted into the radio signals that neutrinos give off during a collision. For De Vries’s experiment, researchers at the Slac National Accelerator Laboratory in California fired a beam of high-energy electrons at a plastic target. It succeeded in imitating the particle track left by a neutrino during a collision in the Antarctic ice.

While one antenna fired radio radiation at the target, other antennas were used to keep watch. And indeed, the other antennas were able to detect the particle trail. This proves that radar technology can be used in the search for cosmic neutrinos. The findings have been published in the Physical Review Letters.

“We have shown that the principle works,” said de Vries, who is leading the team in California together with Dr Steven Prohira of Ohio State University. “The trace left by a high-energy neutrino will obviously be different from the trace measured during this experiment, but based on our simulations, we think we will be able to detect it if we send a more powerful radar wave into the ice.”

Next year, the team hopes to build a rig to test the radar method in Antarctica, as a stepping stone to creating a detector that can measure actual particle tracks. “The kind of neutrinos we will be able to detect with radar technology will tell us more about the extremely energetic astronomical phenomena in our universe,” says de Vries, who is part of VUB’s Elementary Particle Physics lab. “This may even bring new physics to light.”

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