Using the world’s most sensitive detector, researchers were able to set the limit on the effective size of dark matter particles to its most precise yet. Their findings were presented at a seminar in Gran Sasso Underground Laboratory in Italy.
Effective Size Of Dark Matter Particle
A collaboration of 165 scientists from 12 countries has now led to the establishment of limits of the effective size of dark matter particles to 4.1X10-47 square centimeters. The results were gathered from the analysis of 279 days of data from the XENON1T wherein no events were recorded in the cleanest and innermost part of the detector, suggesting that the dark matter particles are likely smaller than expected.
“We now have the tightest limit for what is known as ‘the WIMP-nucleon cross section,’ which is a measure of the effective size of dark matter,” said Ethan Brown of the XENON Collaboration who is also an assistant professor at Rensselaer Polytechnic Institute.
The XENON1T was meant to capture the flash that liquid xenon makes during particle interaction, thereby capturing the moment when a dark matter particle interacts or collides with a xenon nucleus.
That said, as rare as interactions between xenon and dark matter particles are, interactions between xenon and other elements are fairly common. This is why the detector also has a complex purification system that continually scrubs the xenon in the detector, and to minimize the possibility of contamination.
Further, the detector is also protected from natural radiation as it sits within a cryostat that’s submerged in water, and it’s also in an underground laboratory where the mountain above it can protect it from cosmic rays.
Dark Matter WIMPs
Dark matter is believed to be five times as plentiful as ordinary matter in the universe. Several efforts have proven the existence of dark matter, but so far, its interactions with ordinary particles are so weak that it has been rather difficult to observe or measure.
In fact, dark matter particles called “weakly interacting massive particles” (WIMPs) are unseen and they rarely get in contact with ordinary particles, which is why their existence has not been confirmed. Because of this, scientists built sensitive detectors that can hopefully observe interactions between dark matter particles and ordinary particles.
For the past 16 years, the XENON Collaboration has been doing just that, and they have since operated three sensitive detectors. Their latest creation is the XENON1T, which is the most sensitive dark matter detector and most powerful venture of the XENON Collaboration to date.