Scientists see “rarest event ever recorded” in search for dark matter

Scientists have observed an extremely rare particle physics event using a detector that’s hunting for dark matter, the mysterious material that physicists have yet to observe. The universe is almost 14 billion years old. This process takes a trillion times longer.

Researchers from the XENON Collaboration reported their findings in a paper that appeared in the journal Nature. They claimed to have seen the radioactive decay of a substance called xenon-124, an isotope of the element xenon, a colorless and odorless noble gas found in minute quantities in the atmosphere. A “two-neutrino double electron capture” is an occurrence that has baffled scientists for many years.

The XENON1T detector has allowed scientists to observe an ultra-rare event: the radioactive decay of xenon-124.

By simultaneously absorbing two electrons from one atomic shell and emitting two electron neutrinos, two protons in a nucleus are transformed into neutrons. Following this, the event emits a predicted cascade of Auger electrons and X-rays, which scientists search for using an ultra-sensitive detector that lies 5,000 feet below Italy’s Gran Sasso mountain, insulated from cosmic rays.

Ethan Brown, a professor of physics at Rensselaer Polytechnic Institute and a co-author of the paper, told Newsweek that “we have proved that we can detect the rarest occurrences ever recorded.” The most important discovery is that an isotope that was previously believed to be fully stable is now known to degrade over incredibly long timescales.

How much time is that period? The scientists calculated that the half-life of xenon-124 is about 18 sextillion years, or 18,000,000,000,000,000 years, which is more than one trillion times the age of our universe. According to the team’s statement, it is the slowest process that has ever been directly measured.

Brown told The Independent, “It’s incredible to have watched this process and it demonstrates that our detector can measure the rarest object ever recorded.”

The XENON1T experiment was created to search for dark matter, a new type of stuff that makes up 85% of the universe’s mass yet interacts so seldom that it has never been seen, according to Brown. We can do a variety of different tests involving unusual physics since this experiment is so sensitive to extremely rare occurrences. This xenon-124 decay is one of them. We set out to investigate if we could witness this uncommon disintegration, even though our main objective had always been the finding of dark matter.

The scientists had to fill their detector with 3.2 tons of liquid xenon to expose it to a significant number of xenon atoms in order to have that excellent probability.

Brown explained, “XENON1T is a huge vat of liquid xenon surrounded by light sensors. “We receive a small flash of light and a tiny lot of charge out of the xenon when dark matter collides in it, or when a radioactive decay happens within. With the help of the light sensors, we measure them and learn as much as we can about the initial incident that generated the light and charge.

The latest results may aid research into neutrinos, one of the universe’s least known basic particles, even if the researchers did not observe dark matter, which was the detector’s primary goal.

It demonstrates how much more adaptable the XENON detector technology we utilize for dark matter is, said Ph.D. candidate Christian Wittweg of the University of Münster in Germany to Gizmodo. “We created an experiment sensitive enough to look for dark matter,” the author writes. “We get all these amazing analyses… for nothing.”

The team intends to utilize its more recent XENONnT detector to keep looking for dark matter, a mysterious substance that is thought to make up around 26.8% of the universe’s total mass.