Max Planck team wants to detect dark matter using sugar

Dark matter is said to make up the majority of the universe. However, it has not yet been detected experimentally. Perhaps a sweetener can help. A team at the Max Planck Institute for Physics (MPP) is testing this.

The working group intends to use sucrose, i.e., conventional table sugar, as a detector material to detect Weakly Interacting Massive Particles (WIMP). These weakly interacting massive particles are considered candidates for dark matter particles.

The detection of such a particle would occur through an interaction with another particle: if the dark matter particle hits a nucleus, it bounces back. The recoil energy can be measured as a minimal temperature increase and as faint light, explains the CRESST team. CRESST, an acronym for Cryogenic Rare Event Search with Superconducting Thermometers, is a European experiment searching for dark matter.

Sugar is well-suited as a detector because it consists of carbon, oxygen, and a total of 22 hydrogen atoms. Hydrogen is the lightest element of all – and the lighter a nucleus, the better, says CRESST spokesperson Federica Petricca: “Because a very light dark matter particle can hardly disturb a heavy nucleus, just as little as a marble hitting a bowling ball.”

Special Sugar Crystals

However, sugar from the grocery store shelf cannot simply be used as a detector. The crystals must be very large and particularly pure, which is why the team grows them itself in a multi-week process. Additionally, the sugar is equipped with temperature and light sensors.

As a test, the team exposed the sugar sensor to a radioactive source. It recorded a light signal and a temperature increase. “The result surprised us, because sucrose forms a rather soft crystal,” explains Petricca. Materials with a rigid crystal lattice are actually better suited, as a particle collision leads to a greater temperature change.

Dark matter is estimated to make up about 85 percent of the universe and is considered its scaffolding. However, it is invisible: it does not emit light, nor does it reflect, absorb, or block it. Detection must therefore be indirect. Sugar is thus fundamentally suitable as a detector, says Petricca. “However, it will only become clear after many more tests and in comparison with other materials whether a detector made of sucrose can be realized.”

(wpl)