Wednesday, May 1, 2019

Physicists Detect the Decay of a Xenon-124 Nucleus

When it comes to cosmic timescales, the human mind is often incapable of grasping their sheer enormity. So when a group of scientists announce they have observed an event which on should take on average over one trillion times the current age of the universe to occur, there are serious implications for physics.

The team of physicists working on the XENON collaboration have detected the decay of an atomic nucleus of Xenon-124. This detection is significant because the isotope in question has a half-life of 1.8x1022 years, which is 1.3x1012 times longer than the current age of the universe, making it the longest process to be directly observed. For perspective, if the present age of the universe was scaled down to one second, the half-life of Xenon-124 would be 41,360 years.

Interestingly, the XENON collaboration is not a team searching for rare radioactive decay processes. The primary goal of XENON is the detection of the most common substance in the universe: dark matter. The observation made used the XENON1T dark matter detector, a tank of 3,200 kilograms of super-cooled xenon located 1,400 metres below the Gran Sasso massif in Italy.

Hidden deep underground, this tank of xenon is effectively shielded from cosmic rays, so the only thing capable of disrupting the xenon atoms is a chance collision with dark matter particles, which can then be detected from the resulting shower of particles. Based on these results, however, the XENON1T detector is also capable of detecting the radioactive decay of Xenon-124, which has a different particle signature than a dark matter collision.

From technology designed to detect something seemingly common, science has instead found something unimaginably rare.

Read the official press release and research paper here:

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