Search for dark matter finds excess positrons
An international team running the Alpha Magnetic Spectrometer (AMS) has announced the results of its search for dark matter during a CERN seminar. The team has discovered an excess of positrons in the flow of cosmic rays.
The Alpha Magnetic Spectrometer (AMS) is been floating around 400km above earth, where over the past year and a half, it has recorded some 25 billion detections of cosmic rays, including 400,000 positrons with energies between 0.5 and 350 GeV. The positron is the antiparticle to the electron and the AMS has thus completed the largest ever recording of antiparticles in space. The concentration of positrons increases in the 10-250 GeV range, and leveling out in the 20-250 GeV region.
This excess in positrons are consistent with the theory that positrons originate from the annihilation of dark matter in space, but the research is not yet conclusive enough to determine this as being the absolute origin of antiparticles. "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." Says Samuel Ting, spokesperson for the AMS
Possible distribution of matter and energy in the universe
The theory linking positrons to dark matter is known as Supersymmetry. It states that when two dark matter particles collide, they destroy each other, but may produce a positron as a byproduct. The theory is consistent with the observed positron distribution detected by AMS, which was uniform. Unfortunately, at this time, the observations have not been able to rule out the opposing theory that positrons originate from pulsars on the galactic plane.
"When you take a new precision instrument into a new regime, you tend to see many new results, and we hope this will be the first of many," added Ting during the CERN seminar, "AMS is the first experiment to measure to 1% accuracy in space. It is this level of precision that will allow us to tell whether our current positron observation has a Dark Matter or pulsar origin."
The same theory also suggests a hitherto unproven cut-off exists for energies above the mass range of dark matter particles, but the AMS has as of yet not been able to prove this.