For the first time in history, scientists directly observed a exotic kind of radioactive decay called dvuhmetrovy double electron capture. This decay is observed in the atoms of xenon-124, occurs so seldom that in order for a sample of xenon-124 is reduced by half, you will need 18 sextillion years (18 with 21 zeros), respectively, it is extremely hard to detect. The long-awaited observation dvukhatomnogo double electron capture, which was announced on April 25 in Nature, lays the Foundation for the scientists who are trying to see have not seen, even more rare version of this decay: neutrinoless double electron capture.
The rare decay of atoms
Observation of this process would have confirmed that subatomic particles neutrinos have a private antivimentin partners-particles, and would help to solve the mystery of why our universe is almost entirely made of matter and not of antimatter.
“The community was quite noisy after the release of the results,” said Lindley Winslow, a physicist from the Massachusetts Institute of technology.
Xenon-124 is an isotope form of an element with the same number of protons, but different number of neutrons (the number 124 refers to the total number of protons and neutrons in the nucleus). This is one of the few radioactive isotopes that decay in dvukhatomnogo result of double electron capture. But atoms are so rarely exposed to this degradation, scientists need to track a huge number of xenon atoms, to get a chance to witness it.
The physicist of elementary particles Christian Wittig from münster University in Germany and his colleagues searched for the signature dvukhatomnogo double electron capture with a detector XENON1T, the machine normally used to hunt for dark matter. This device is protected from background radiation in the underground National laboratory of Gran Sasso in Italy, has about three metric tons of xenon.
When dahatelnom double electron capture nucleus captures two electrons from the surrounding electron shells, turning two protons in the nucleus a neutrons and spitting out two neutrinos.the neutrino cannot be detected, the capture process of electrons emits x-rays, and ejects other electrons from the atom which can be detected.
From February 2017 to February 2018 XENON1T collected tales of double electron capture with the two neutrinos are approximately 126 times. From this it became clear that the half-life of xenon-124 is approximately 18 sextillion years, which is the longest half-life ever measured directly with a radioactive substance — and about a trillion times longer than the age of the Universe.