The first published results from the Alpha Magnetic Spectrometer (AMS) physics experiment on the International Space Station were announced today and though the result is the most precise measurement to date of the ratio of positrons to electrons in cosmic rays, we still have not caught our first glimpse into dark matter.
The AMS experiment, constructed at universities around the world and assembled at the European Organization for Nuclear Research (CERN), is the world's most precise detector of cosmic rays. It was installed on the Space Station May 19th, 2011 after having been brought into orbit on the last flight of NASA's space shuttle Endeavour. To date it has measured over 30 billion cosmic ray events.
The science goals of AMS include the search for dark matter, antimatter, and new physical phenomena. The detector provides high-precision measurements of cosmic ray particle fluxes, their ratios and gamma rays. This first physics result from AMS is based on 18 months of operation, during which time AMS measured 6,800,000 cosmic ray electrons in the energy range of a half-billion to a trillion electron volts, and over 400,000 positrons (positive electrons), the largest number of energetic antimatter particles directly measured from space. The importance of this measurement is that it could eventually provide a "smoking gun" that certain dark matter particles exist and that dark matter particles and antiparticles are annihilating each other in space.
Although the data do not show a "smoking gun" at this time, this first high-precision (~1% error) measurement of the spectrum has interesting features not seen before that future data may help clarify. With additional data in the coming years, AMS has the potential to shed light on dark matter.
"This result is the first step," said AMS collaboration spokesman and Nobel Laureate Samuel Ting, "the beginning of a series of high precision experimental results from the Alpha Magnetic Spectrometer. This shows that a large international particle physics collaboration can work together to do particle physics in space."