Darkish matter scientists observe the ‘rarest occasion ever recorded’



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

Xenon Collaboration

In a subterranean laboratory, a couple of mile beneath Italy’s Gran Sasso mountains, scientists are looking for darkish matter utilizing an extremely highly effective detector filled with liquid xenon. Of their seek for the elusive particle, they noticed one thing else fully.

Their darkish matter detector witnessed the rarest occasion ever recorded: the radioactive decay of xenon-124.

The analysis, revealed in Nature on April 24, is authored by the XENON collaboration, a mission consisting of over 160 scientists aiming to find darkish matter utilizing the XENON1T detector. Their findings show xenon-124, an isotope of the aspect xenon utilized in flash lamps and ion thrusters in spacecraft, will not be as steady as was as soon as suspected.

The detector consists of a cylindrical tank full of over 7,000 kilos of liquid xenon cooled to -139 levels Fahrenheit (-95 levels Celsius). It is so far underground that it blocks out any radioactive interference that might mess with darkish matter measurements.   

The supreme fine-tuning and clear measurements allowed by XENON1T enabled scientists to witness xenon-124 decay away at a charge that far exceeds the lifetime of the universe. To take action, they measured the half-life of the atoms. 

“Medication are absorbed by the physique with a half-life of minutes to hours, organisms reproduce with a half-life of days or years, chemical reactions occur with a half-life of seconds,” explains Ethan Brown, a co-author on the research. “The half-life for this course of is the slowest one ever noticed, greater than a trillion occasions longer than your complete historical past of the universe.”

Xenon-124’s half-life is 1.8 × 10^22 years (18,000,000,000,000,000,000,000), making the statement an “ultra-rare” occasion, based on the analysis collaboration.

It’s possible you’ll be considering “If the universe is sort of 14 billion years outdated and this takes a trillion occasions longer… how can we even see it in any respect?” and let me inform you, that is precisely what I used to be considering, too. It isn’t solely a groundbreaking discovery, however a mind-breaking one.

The analysis staff weren’t simply holding a magnifying glass over a single xenon atom, hoping to see it decay. In XENON1T there’s a practically unfathomable quantity of xenon atoms, due to all that liquid xenon, successfully permitting the scientists to “watch” trillions of atoms. Whereas solely a small fraction of these are xenon-124, that also supplies a superb probability of nabbing the physics needle in a haystack. And moderately than observing the atoms decaying immediately, scientists search for indicators of decay — the X-rays and electrons launched when xenon-124 decays.

The collaboration was capable of spot 126 such processes over two years, which allowed them to calculate the mindbogglingly lengthy half-life.

Whereas the decay of xenon-124 will not be associated to the hunt for darkish matter, the invention supplies an enormous enhance in confidence that the XENON1T detector may at some point present proof for darkish matter. Brown calls it a “big step in validating our means to measure uncommon physics.

“This reveals simply how properly we perceive our detector and makes us extraordinarily assured in our outcomes for the seek for darkish matter,” he says.

XENON1T was shut down in December 2018 for a deliberate improve often known as XENONnT. The brand new detector will probably be 3 times bigger, holding much more liquid xenon, making it much more delicate to uncommon occasions and, hopefully, the invention of darkish matter particles.


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