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Artist’s concept of a stream of neutrinos hitting Earth.
Neutrino experiments at Fermilab center in Batavia, Illinois, may soon reveal why the universe holds more matter than antimatter. As of now, scientists were able to find first evidence backing previous theories that the elusive subatomic particles oscillate, or change their nature as they travel.
But detecting neutrinos is not that easy. They are subatomic, have no charge, and do not usually interact with other particles. In fact they can travel through matter as if space was empty.
During their experiments dubbed NOvA, Fermilab scientists used a pair of neutrino detectors located 500 miles away from one another – the Near Detector positioned in Batavia, Illinois and the Far Detector in Ash River, Minnesota.
Physicists long theorized that the particles were of three types: mu, tau, and electron, but they weren’t quite sure if neutrinos could morph from one type to another before colliding with other particles.
The initial findings during the NOvA experiments, however, showed that the universe is filled with oscillating neutrinos. And they don’t change their nature only once during their lifetime. They do it several times, scientists explained.
During a NOvA experiment, a beam loaded with mu neutrinos is shot by the Illinois detector all the way to the neutrino detector in Minnesota. In their 500-mile interstate trip, neutrinos change their status from mu to electron neutrinos, according to Far Detector’s data. Since neutrinos are subatomic and have little to no interaction with matter around them they can travel through Earth’s crust as if it was empty space. That’s why NOvA experiments required no tunnels as Europe’s particle collider does.
But the results suggesting that neutrinos oscillate were gathered indirectly by sifting through data on particle collisions recorded by the Far detector. The Minnesota detector found 33 mu and 6 electron neutrinos. This means that the mu-neutrinos oscillated at least six times. Yet, there were more mu neutrinos that started their trip at the Near Detector. Scientists believe that those morphed into tau neutrinos. Nevertheless, that type of particles cannot be detected with current machinery.
Researchers hope that current detectors may help them better understand neutrinos’ nature and have a glance at antineutrinos. By comparing that ratio, the research team hopes to provide an explanation to current matter-antimatter balance in the universe. Scientists argue that if there was slightly more antimatter than matter the whole visible universe would have imploded into a brief flash of gamma rays. A paper on the experiments was published August 6.
Image Source: Catalyst Yogy
