Shedding light on dark matter
18 Apr 2018 by hjqbcptqcm.d hjqbcptqcm.d
Physicists have claimed the discovery of a new material that may be able to directly detect dark matter.
The material, known as a scintillator, should be sensitive to dark matter that is lighter than a proton allowing the search for dark matter to enter a largely unexplored mass range.
Professor Stephen Derenzo of the electrical engineering and computer sciences lab at UC Berkeley in the US said: “When the new scintillation detector is combined with a cryogenic photodetector – which can detect light at very low temperatures – the result will be a workhorse useful in the search for dark matter in a largely unexplored mass range.”
Astronomers have observed that galaxies rotate with such great speed they should be torn apart, yet they are not. It is as if some hidden mass is holding the galaxies together by exerting a gravitational force on ordinary matter. This unknown mass is known as dark matter. Ordinary matter makes up only 5% of all content in the universe, whereas dark matter constitutes more than 25% of everything. The remaining 70% is known as dark energy, but no one has ever directly observed dark matter or dark energy.
The US team think the discovery of a new material that may be able to directly detect dark matter. Operating at near absolute zero, it detects electrons recoiling from collisions with dark matter particles and consists of a target of ordinary matter, in this case gallium arsenide, or GaAs, doped by a small amount of other elements. The target emits a photon (a particle of light) after an electron in the target is excited to a high energy state through a collision with a dark matter particle.
The discovery represents the first time that n-type GaAs, chosen for its low band gap energy, has been used as a cryogenic scintillation detector. When the final device is constructed, experiments will be carried out deep underground to shield the detector from cosmic rays and other potential sources of false signals.
To date, nothing is actually known about dark matter’s mass, and its detection would have huge implications for our understanding of the universe.
