A group of physicists from the United States for the first time received during the CDMS experiment with underground cryogenic detectors direct evidence for the existence of so-called "WIMP" - dark matter particles. Now, before the discovery of a mysterious substance scientists is just one step, according to the website of the experiment.
Dark matter, an invisible form of matter called, the presence of which scientists are judged only by its gravitational effects. It does not emit, absorb or reflect electromagnetic radiation. It is known that the share of "normal" matter accounts for about 4.9% of the mass of the universe, while the share of the dark - 26.8%. Dark matter is a combination of heavy weakly interacting particles - "WIMPs" (Weakly Interacting Massive Particles).
American physicists were able to create in the state of Minnesota in the abandoned mine at a depth of 600 meters observatory Cryogenic Dark Matter Search (Cryogenic Dark Matter Search II - CDMS II). It consists of germanium detectors which are comparable in size with a hockey puck, and cooled to a temperature very close to absolute zero. The purpose of the detectors is to fix the cases of elastic collisions of WIMPs with nuclei of atoms. Scientists in 2010 managed to capture two events, but the response, as shown by analysis to be false. Therefore, experts have decided to use a more secure future silicon detectors.
And eight silicon detectors finally recorded three events WIMP collisions with the nuclei of atoms. The level of accuracy reached 99.8%, which means it is really new particles, and not the result of random fluctuations. WIMP mass, according to information received, shall be 8.6 GeV, that is, to be approximately 8.5 times heavier than the proton.
"To open the required level of 5 sigma or better. This is certainly a very interesting result, but ... additional data are required to more accurately confirm the discovery," - said Rupak Maharata (Rupak Mahapatra), one of the participants in the experiment from the University of Texas A & M.