Cosmology Physics

Dark matter search comes up empty

An online news reportfrom, titled “Scientists looking for invisible dark matter can’t find any,” reported the following:

Scientists have come up empty-handed in their latest effort to find elusive dark matter, the plentiful stuff that helps galaxies like ours form.

For three years, scientists have been looking for dark matter—which though invisible, makes up more than four-fifths of the universe’s matter—nearly a mile underground in a former gold mine in Lead, South Dakota. But on Thursday they announced at a conference in England that they didn’t find what they were searching for, despite sensitive equipment that exceeded technological goals in a project that cost $10 million to build.

Lead co-investigator Richard Gaitskell explains the experiment.

The experiment, called the Large Underground Xenon experiment or LUX, was found to be 4 times its original design sensitivity. It involves a detector that consists of about a third of a ton of supercooled xenon in a tank festooned with light sensors, each capable of detecting a single photon. As the so-called WIMPs (Weakly Interacting Massive Particles) pass through the tank, they should, on very rare occasions, bump into the nucleus of a xenon atom. Those bumps cause the nucleus to recoil, creating a tiny flash of light and an ion charge, both of which are expected to be picked up by LUX sensors.

The experiment is located in a hole a mile (1.6 km) underground in an old gold mine to exclude all sorts of background sources that might give false signals. The alleged dark matter particles are hardly affected by the intervening matter and pass mostly undisturbed through the planet, or so the theory alleges. But alas nothing has been detected. In fact for at least 40 years now no such local lab experiment has found anything.

Scientists are already starting to revamp the South Dakota mine site for a $50 million larger, higher-tech version of LUX, called LZ, that will be 70 times more sensitive and should start operations in 2020, said Brown University’s Richard Gaitskell, another scientific spokesman for LUX.1