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e said the results bear on the mystery of dark matter,

"It will not be a minor paper,"

important enough that the scientists rewrote the paper 30 times before they were satisfied with it

it represents a "small step" in figuring out what dark matter is, and perhaps not the final answer

Some physics theories suggest that dark matter is made of WIMPS (weakly interacting massive particles), a class of particles that are their own antimatter partner particles

When matter and antimatter partners meet, they annihilate each other, so if two WIMPs collided, they would be destroyed, releasing a pair of daughter particles — an electron and its antimatter counterpart, the positron, in the process

Alpha Magnetic Spectrometer has the potential to detect the positrons and electrons produced by dark matter annihilations in the Milky Way

was installed on the International Space Station in May 2011, and so far, it has detected 25 billion particle events, including about 8 billion electrons and positrons

This first science paper will report how many of each were found, and what their energies are

If the experiment detected an abundance of positrons peaking at a certain energy, that could indicate a detection of dark matter,

while electrons are abundant in the universe around us, there are fewer known processes that could give rise to positrons

The smoking gun signature is a rise and then a dramatic fall" in the number of positrons with respect to energy

he positrons produced by dark matter annihilation would have a very specific energy, depending on the mass of the WIMPs making up dark matter

Another telling sign will be the question of whether positrons appear to be coming from one direction in space, or from all around

f they're from dark matter, scientists expect them to be spread evenly through space, but if they're created by some normal astrophysical process, such as a star explosion, then they would originate in a single direction

There is a lot of stuff that can mimic dark matter,"

Regardless of whether AMS has found dark matter yet, the scientists said they expected the question of dark matter's origin to become clearer soon

the first results from the Alpha Magnetic Spectrometer, known by its acronym AMS,

show evidence of new physics phenomena that could be the strange and unknown dark matter or could be energy that originates from pulsars

expects a more definitive answer in a matter of months

Unraveling the mystery of dark matter could help scientists better understand the composition of our universe and, more particularly, what holds galaxies together

The 7-ton detector with a 3-foot magnet ring at its core was sent into space in 2011

The device is transmitting its data to CERN, where it is being analyzed

For 80 years scientists have theorized the existence of dark matter but have never actually observed it directly

They have looked for it in accelerators that smash particles together at high speed

deep underground with special detectors

no luck

there's a third way: looking in space for the results of rare dark matter collisions

If particles of dark matter crash and annihilate each other, they should leave a footprint of positrons—the anti-matter version of electrons—at high energy levels

found some. But they could also be signs of pulsars

What's key is the curve of the plot of those positrons. If the curve is one shape, it points to dark matter. If it's another, it points to pulsars

they should know the curve—and the suspect—soon

since its installation on 19 May 2011 it has measured over 30 billion cosmic rays at energies up to trillions of electron volts

Its permanent magnet and array of precision particle detectors collect and identify charged cosmic rays passing through AMS from the far reaches of space

Over its long duration mission on the ISS, AMS will record signals from 16 billion cosmic rays every year and transmit them to Earth for analysis by the AMS Collaboration.

In the initial 18 month period of space operations, from 19 May 2011 to 10 December 2012, AMS analyzed 25 billion primary cosmic ray events

Of these,

6.8 million, were unambiguously identified as electrons and their antimatter counterpart, positrons.

Positrons are clearly distinguished from this background through the robust rejection power of AMS of more than one in one million

Currently, the total number of positrons identified by AMS, in excess of 400,000, is the largest number of energetic antimatter particles directly measured and analyzed from space

The exact shape of the spectrum, as shown in Figure 2, extended to higher energies, will ultimately determine whether this spectrum originates from the collision of dark matter particles or from pulsars in the galaxy

by measuring the ratio between positrons and electrons and by studying the behavior of any excess across the energy spectrum, a better understanding of the origin of dark matter and other physics phenomena can be obtained