Diamond detectors could aid the search for dark matter

A new idea for detecting dark matter really sparkles.

Diamonds could be used to search for the mysterious substance, a team of scientists suggests. Detectors containing the crystals could spot potential dark matter particles with relatively low masses, the researchers report in the June 15 Physical Review D.

Dark matter is an unidentified substance that scientists think must exist to explain cosmic observations such as the speeds at which stars move in galaxies. The most popular idea has been that dark matter consists of subatomic particles known as WIMPs, or weakly interacting massive particles. But extensive searches for those massive WIMPs have come up empty (SN: 11/12/16, p. 14).

With the WIMPs wimping out, scientists have begun looking for potential dark matter particles that are less massive (SN Online: 4/9/18). That’s where the diamond detectors could shine. And lab-grown diamonds are now available and relatively affordable.

The crystals would be cooled to near absolute zero (–273.15° Celsius) and outfitted with sensors to detect sound waves that could be produced when a dark matter particle slams into an atomic nucleus or an electron in the diamond.

Scientists previously have made similar detectors using other types of crystals, such as germanium and silicon. But diamond has some additional benefits. The carbon atoms that make up diamond are lighter than atoms of silicon or germanium, so diamond detectors could detect lighter dark matter particles colliding into the atomic nuclei. And diamond can be made more pure than other crystals, composed mostly of a single type, or isotope, of carbon. That makes it easier to measure vibrations set off by potential dark matter particles, says study coauthor Noah Kurinsky, a physicist at Fermilab in Batavia, Ill. “It is the ultimate perfect crystal.”