MAY 02, 2019 10:36 AM PDT

The Accidental Discovery of An Exotic Nuclear Decay

WRITTEN BY: Daniel Duan


Xenon-filled dark matter detector (The XENON collaboration)Numerous scientific discoveries were made by accident. Sometimes, the findings even crossed into a different field other than the one scientists were exploring.

The XENON collaboration is formed by an international group of astrophysicists, whose interest is to search for "dark matter", an elusive entity that supposedly provides our universe massive gravitational pull so it won't expand out of control. In their underground research facility in central Italy, the researchers accidentally observed a rare radioactive decay process that would have otherwise gone unnoticed for many years to come, all thanks to their dark matter detector that's filled with 3,500 kg (7,716 lb) of liquid xenon. 

Xenon-124, an isotope whose nucleus is made up of 54 protons and 70 neutrons, has always been considered a stable form of the element. The consistent detection of an unknown source of X-rays and Auger electrons at the XENON facility caught the researchers' attention. With over one year of direct repeated measurement, they successfully confirmed that the xenon in their detector undergoes a rare form of radioactive decay, known as two-neutrino double electron capture. 

Electron capture is a common form of beta decay, which involves the nucleus of an atom snatching an electron from its own "orbit" and brings it inside. Once the electron came into contact with a proton, the two forms a neutron, a subatomic particle weighed the same as a proton but have no charge. At the same time, a neutrino is sent out of the nucleus.

Two-neutrino double electron capture is similar to what mentioned above but simultaneously happens to two electron-proton pairs within the same atom. After having two of its protons converted, a decayed xenon-124 atom turns into tellurium-124, an isotope with exact same atomic weight but less +2 charge in its nucleus. The half-life of xenon-124 was estimated as long as 1.8 × 10^22 years. That's whopping one trillion times the age of our universe. 

Just when you think that the decay of xenon-124 takes a really long time, it is not the isotope with the longest half-life. The champion is tellurium-128, whose half-life is over 160 trillion times greater than the age of the universe, at 2.2 x 10^24 years. 

What's more intriguing, tellurium-128 undergoes double beta decay, a process that turns two neutrons into two protons and releases two electrons. It's comparable to the decay of xenon-124 in the sense that both lose a pair of electrons. But in tellurium-128's case, the electrons travel in a reversed direction. 

The surprising discovery of double electron capture would help scientists test various nuclear models and allow them to carry out a more accurate prediction about the values of the nuclear matrix elements, a quantity that plays an indispensable role in nuclear physics.

This research was recently published in the journal Nature.

While Looking for Dark Matter, Scientists Discover Something Way Cooler (Anton Petrov)

Source: Nature

About the Author
  • Graduated with a bachelor degree in Pharmaceutical Science and a master degree in neuropharmacology, Daniel is a radiopharmaceutical and radiobiology expert based in Ottawa, Canada. With years of experience in biomedical R&D, Daniel is very into writing. He is constantly fascinated by what's happening in the world of science. He hopes to capture the public's interest and promote scientific literacy with his trending news articles. The recurring topics in his Chemistry & Physics trending news section include alternative energy, material science, theoretical physics, medical imaging, and green chemistry.
You May Also Like
MAR 03, 2020
Chemistry & Physics
MAR 03, 2020
All About Fluorocarbon Use in Aircraft and Auto Engines
Fluorocarbon rubber is a popular choice for use in aircraft and auto engines. It is a material with high resistance to c ...
MAR 06, 2020
Chemistry & Physics
MAR 06, 2020
Father of the Dyson Sphere Passed Away
Last Friday, February 28, 2020, the world said goodbye to Freeman Dyson, was a British American physicist and mathematic ...
MAR 15, 2020
Space & Astronomy
MAR 15, 2020
This Exoplanet Rains... Iron!?
Many of us take the Earth and its many ‘normal’ characteristics for granted, but there are so many exoplanet ...
APR 28, 2020
Space & Astronomy
APR 28, 2020
NASA's Swift Telescope Measured the Water Loss of This Interstellar Comet
When the interstellar comet 2l/Borisov made its first appearance in our solar system, astronomers were quick to turn the ...
APR 29, 2020
Chemistry & Physics
APR 29, 2020
New method hospitals can use to produce hydrogen peroxide
In a collaboration between the University of California San Diego, Columbia University, Brookhaven National Laboratory, ...
MAY 01, 2020
Chemistry & Physics
MAY 01, 2020
Giant elliptical galaxies are not likely to hold intelligent life
A previous paper published in 2015 theorized that giant elliptical galaxies would be 10,000 times more likely than spira ...
Loading Comments...