By Andrew Grant
A $2-billion experiment on the International Space Station has released the first data from its unprecedented census of the charged subatomic particles whizzing by Earth. Although the results, presented April 3 at a seminar at CERN in Geneva, largely confirm previous observations, researchers hope they will lead to discovering the identity of dark matter, an invisible form of matter that outweighs normal matter in the universe by more than 5 to 1.
The Alpha Magnetic Spectrometer is the latest and most ambitious attempt to uncover the identity of dark matter by looking for cosmic rays, which are charged subatomic particles cruising through space. Theoretical physicists have proposed that dark matter could be made up of exotic particles that can slam into and annihilate each other, creating detectable cosmic rays such as electrons and their antimatter partners, positrons.
This first batch of AMS results, published April 3 in Physical Review Letters, encompasses about 25 billion particles detected over the course of a year and a half, including 6.8 million measurements of the electrons and positrons that could come from dark matter. AMS improved the precision of earlier data, detected particles at higher energies than previous instruments and found that the particles arrive in equal amounts from all directions.