spacetoday.net: ISS experiment detects potential evidence for dark matter

Posted: Thu, Apr 4, 2013, 6:59 AM ET (1059 GMT)
STS-134: AMS being installed on ISS (NASA)

A billion-dollar experiment mounted on the International Space Station has detected evidence for dark matter, although scientists caution that there are other explanations for the data. The first data from Alpha Magnetic Spectrometer (AMS) instrument, announced Wednesday at CERN in Geneva, shows an increase in the fraction of positrons compared to electrons as energies increase, from 10 to 250 billion electron volts. The AMS data shows no evidence of anisotropy, or variation in the data by direction, indicating the positrons do no come from a single source, such as the center of the galaxy. That data is consistent with those positrons forming from the collision of dark matter particles, as some scientists have hypothesized, but could have other explanations, such as being produced by pulsars distributed in the galactic plane. Additional observations at higher energies may allow scientists be able to distinguish between the different explanations. AMS, a multinational experiment, was installed on the exterior of the ISS on the next-to-last shuttle mission, STS-134, in 2011.