On April 03, 2013, the international team running the Alpha Magnetic Spectrometer (AMS) announced the first results in its search for dark matter, reporting the observation of an excess of positrons in the cosmic ray flux, feeding our curiosity behind one of the most important mysteries of physics today. Accounting for over a quarter of the universe's mass-energy balance, dark matter can be observed indirectly through its interaction with visible matter but has yet to be directly detected.
"AMS has made an amazingly precise measurement of the flux of high-energy antimatter electrons from outer space. The anti-electron rate they find is much larger than what we expect from ordinary astrophysical processes, and may be coming from the annihilation of dark matter particles in our galaxy," explains TRIUMF research scientist David Morrissey.
AMS is installed on the International Space Station, thus providing a unique platform for the detector to chart a new realm of fundamental physics research not quite possible to achieve on the Earth's surface as all primary charged particles and high-energy gamma rays are absorbed by the Earth's atmosphere.
"It's interesting that our quest to understand dark matter puts us both high up in space, where we might see the products of dark matter annihilation streaming towards us, and deep underground in places like SNOLab in Canada, where shielded from cosmic rays, we can look for the telltale signals of dark matter particles directly interacting in our detectors," explains Hirohisa Tanaka (UBC).
"The AMS result is a great example of the complementarity of experiments on Earth and in space," said CERN Director General Rolf Heuer. "Working in tandem, I think we can be confident of a resolution to the dark matter enigma sometime in the next few years."
Searches for dark matter are carried out in space-borne experiments such as AMS, as well as on the Earth at the Large Hadron Collider and a range of experiments installed in deep underground laboratories.
"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," said AMS spokesperson, Samuel Ting.
"We had our first taste of the impressive capabilities of AMS," said Hirohisa, but researchers are not yet satiated. "To test whether the signal really is from dark matter, we will need to combine more data from AMS and other space-based experiments with direct searches for dark matter in deep underground detectors and at high-energy particle colliders like the LHC. The hunt is on!"
The AMS detector is operated by a large international collaboration led by Nobel laureate Samuel Ting. AMS involves about 600 researchers from China, Denmark, Finland, France, Germany, Italy, Korea, Mexico, the Netherlands, Portugal, Spain, Switzerland, Taiwan, and the United-States. The AMS detector was assembled at CERN, tested at ESA's ESTEC centre in the Netherlands and launched on 16 May 2011 onboard NASA's Space Shuttle Endeavour.
Further information:http://press.web.cern.ch/backgrounders/first-result-ams-experiment
Content courtesy of a CERN Press Release
With comments from David Morrissey (TRIUMF), Hiro Tanaka (UBC), and Fabrice Retiere (TRIUMF).
Prepared by Melissa Baluk.