Scientists inch closer to observing dark matter

A particle detector attached to the International Space Station has observed the potential signature of the elusive dark matter in the universe, scientists have claimed.
The international team running the Alpha Magnetic Spectrometer (AMS) announced the first results in its search for dark matter that is estimated to constitute 84.5 per cent of the total matter in the universe.
They report the observation of an excess of positrons in the cosmic ray flux.
The results, presented by AMS spokesperson Professor Samuel Ting in a seminar at CERN2, are to be published in the journal Physical Review Letters.
The AMS results are based on some 25 billion recorded events, including 400,000 positrons with energies between 0.5 GeV and 350 GeV, recorded over a year and a half.

This represents the largest collection of antimatter particles recorded in space.

The results are consistent with the positrons originating from the annihilation of dark matter particles in space, but not yet sufficiently conclusive to rule out other explanations.
"As the most precise measurement of the cosmic ray positron flux to date, these results show clearly the power and capabilities of the AMS detector," said Ting.
"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," Ting said in a statement issued by the European Organisation for Nuclear Research (CERN).

Cosmic rays are charged high-energy particles that permeate space. The AMS experiment, installed on the ISS, is designed to study them before they have a chance to interact with the Earth's atmosphere. An excess of antimatter within the cosmic ray flux was first observed around two decades ago.
One possibility, predicted by a theory known as supersymmetry, is that positrons could be produced when two particles of dark matter collide and annihilate.
Assuming an isotropic distribution of dark matter particles, these theories predict the observations made by AMS.
However, the AMS measurement can not yet rule out the alternative explanation that the positrons originate from pulsars distributed around the galactic plane.