Scientists at CERN today announced that the Alpha Magnetic Spectrometer on board the International Space Station has detected its first hints of dark matter, the mysterious and as yet unexplained stuff that makes up the majority of the universe. Dark matter emits no light and hasn’t been detected directly through electromagnetic emissions but rather, through its gravitational effect. The Alpha Magnetic Spectrometer, or AMS, measures cosmic-ray particles in space. The evidence presented, which was derived from 25 billion recorded events, is based on an excess in the cosmic production of anti-electrons, also known as positrons, as measured in space (where it is easier to detect). The scientists noted that the increase in the ratio of positrons were found in the 10 billion to 250 billion electron volt range (10 GeV to 250 GeV), showed no significant variation, and had no preferred incoming direction – just what scientists have expected to see from positrons created by dark-matter annihilation.
“Physicists have suggested that dark matter is made of WIMPs, or weakly interacting massive particles, which almost never interact with normal matter particles. WIMPs are thought to be their own antimatter partner particles, so when two WIMPS meet, they would annihilate each other, as matter and antimatter partners destroy each other on contact. The result of such a violent collision between WIMPs would be a positron and an electron.”
The Alpha Magnetic Spectrometer (AMS) is the most sensitive cosmic-ray detector ever put into orbit. The bus-sized device was brought up on the shuttle Endeavour and installed in May 2011, during the shuttle fleet’s second-last mission.
“Over the coming months, AMS will be able to tell us conclusively whether these positrons are a signal for dark matter, or whether they have some other origin.”