Dark Matter Detector Observes Universe’s Rarest Decay Process Ever Measured

The XENON1T detector installed underground at the Gran Sasso Laboratory in Italy. XENON1T collaboration

NYU Abu Dhabi researchers are part of an international research team whose findings are featured on the cover of the journal Nature

Press Release

NYU Abu Dhabi researchers are part of an international team of scientists that has, for the first time, directly measured the rarest nuclear decay process ever recorded by a detector. Using the XENON1T detector, an instrument located at the underground Gran Sasso National Laboratory in Italy designed to search for dark matter with unprecedented sensitivity, the researchers were able to observe the decay of Xenon-124 atomic nuclei for the first time.

This measurement, while not directly linked to the Dark Matter search, is extremely relevant for nuclear physics, as it represents a first step towards the search for other possibly more elusive phenomena. The findings are featured on the cover of the current edition of the journal Nature.

The XENON1T detector installed underground at the Italian Gran Sasso Laboratory. Courtesy of XENON1T collaboration

The Gran Sasso Laboratory of the National Institute for Nuclear Physics (INFN) in Italy, where scientists are currently searching for dark matter particles, is located about 1,400 meters beneath the Gran Sasso massif, well protected from cosmic rays which can produce false signals. The XENON1T uses 3,200 kilograms of liquid xenon at a temperature of –95° C to look for interactions of dark matter particles with the xenon atoms of the detector. The xenon is contained in a cylindrical tank that is placed at the center of a 700,000-liter water tank which further protects the detector from unwanted radioactivity. XENON1T is currently the most sensitive dark matter experiment in the world.

This new study shows that the XENON1T detector is also able to measure other physical phenomena, including double electron capture, a very rare process that is typically obscured by signals from natural radioactivity.

Half-life measures the time it takes for half of the radioactive nuclei present in a substance to decay. The half-life measured for Xenon-124 by the XENON1T detector has the enormously large value of 1.8×1022 years for this process:  approximately one trillion times longer than the age of the universe, making the observed radioactive decay – the double electron capture of Xenon-124 – the rarest process ever observed in a detector.

The XENON program group consists of 21 research groups from the UAE and around the globe. NYU Abu Dhabi is an active partner through the research group led by Associate Dean of Science and Associate Professor of Physics Francesco Arneodo, who joined the University in 2013 after spending 20 years at the Gran Sasso Laboratory, and more than a decade working on the XENON project.


“The XENON1T experiment is a huge scientific and technological achievement. This particular measurement shows its extraordinary performance and opens the door for other exciting measurements in Neutrino Physics. Plus, it shows that if anyone can detect dark matter, it must be us!”

NYU Abu Dhabi Associate Dean of Science and Associate Professor of Physics Francesco Arneodo

Other members from NYU Abu Dhabi who looked after the XENON1T purification system of the water shield and the frontline operations team include:

About NYU Abu Dhabi

NYU Abu Dhabi is the first comprehensive liberal arts and science campus in the Middle East to be operated abroad by a major American research university. NYU Abu Dhabi has integrated a highly-selective liberal arts, engineering and science curriculum with a world center for advanced research and scholarship enabling its students to succeed in an increasingly interdependent world and advance cooperation and progress on humanity’s shared challenges. NYU Abu Dhabi’s high-achieving students have come from 120 nations and speak over 120 languages. Together, NYU's campuses in New York, Abu Dhabi, and Shanghai form the backbone of a unique global university, giving faculty and students opportunities to experience varied learning environments and immersion in other cultures at one or more of the numerous study-abroad sites NYU maintains on six continents.