SoylentNews

RandomFactor [soylentnews.org] writes:

Researchers have observed something that on average takes far longer than the universe has existed. [media.uzh.ch]

The XENON1T detector, which is intended to detect dark matter particles,

has now managed to observe an extremely rare process using the detector – the decay of the Xenon-124 atom, which has an enormously long half-life of 1.8 x 10 to the power of 22 years.

Buried 25 Ice Hockey Rinks deep (1500 meters) below ground in the Gran Sasso mountains in Italy, the detector is shielded from interference by stray radiation.

Until now, researchers using this detector have not yet observed any dark matter particles, but they have now managed to observe the decay of the Xenon-124 atom for the first time. The half-life time measured – i.e. the time span after which half of the radioactive atoms originally present in a sample have decayed away – is over a trillion times longer than the age of the universe

The decay process starts with what is called a double electron capture:

The atomic nucleus of Xenon-124 consists of 54 positively charged protons and 70 neutral neutrons, which are surrounded by several atomic shells occupied by negatively charged electrons. In double electron capture, two protons in the nucleus simultaneously “catch” two electrons from the innermost atomic shell, transform into two neutrons, and emit two neutrinos. As two electrons are then missing in the atomic shell, the other electrons reorganize themselves, with the energy released being carried away by X-rays. However, this is a very rare process which is usually hidden by signals from the omnipresent “normal” radioactivity – in the sealed-off environment of the underground laboratory, however, it has now been possible to observe the process.

This decay process has occurred 126 times in the detector over the past two years allowing the physicists to calculate the halflife of Xenon-124 at 1.8x10^22 years, making this the slowest process ever measured directly.

Original Submission