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FILE - In this July 25, 2012 file picture Director general of CERN Rolf-Dieter Heuer, left, Nobel laureate and AMS spokesperson Samuel C.C. Ting, right, and Mark Kelly, NASA astronaut and commander of mission STS-134, center, brief the media at the Alpha Magnetic Spectrometer (AMS) Payload Operations and Command Center (POCC) at the European Organization for Nuclear Research (CERN) in Meyrin near Geneva, Switzerland. A US $2 billion experiment on the International Space Station is on the verge of explaining one of the more mysterious building blocks of the universe: The dark matter that helps hold the cosmos together. An international team of scientists says the cosmic ray detector has found the first hint of dark matter, which has never yet been directly observed. The team said Wednesday its first results from the Alpha Magnetic Spectrometer, flown into space two years ago, show evidence of a new physics phenomena that could be the strange and unknown matter. Nobel-winning physicist Samuel Ting, who leads the team at the European particle physics laboratory near Geneva, says he expects a more conclusive answer within months. The findings are based on an excess of positrons positively charged subatomic particles. (AP Photo/Keystone/Martial Trezzini,File)

The European Organization for Nuclear Research said it has data that could signal the presence of dark matter, an elusive unseen target that physicists believe makes up as much as a quarter of the universe.

Dark matter is mass that scientists can't detect directly, but whose existence is inferred through its gravitational pull on visible matter, such as planets. Using a collector mounted on the International Space Station for more than a year, scientists at the CERN research institute gathered data on particles, called positrons, they believe may be expelled when dark matter collides in a burst of energy and is destroyed.

The collector gathered data on 400,000 positrons, the antimatter form of electrons, creating the largest collection of such particles recorded in space, according to a statement today. The data are consistent with theories on dark matter and the experiment will confirm in coming months whether the positrons are a signal for dark matter, Geneva-based CERN said.

"It's a confirmation with much better statistical precisions of previous results," William Zajc, chairman of New York-based Columbia University's physics department, said in a telephone interview. Preliminary data on the issue have been collected from other satellites beginning in 2007, he said.

Physicists are awaiting further analysis from CERN on the number of positrons and electrons to tell whether the results may signal dark matter, Zajc said.

Important Mystery

"Dark matter is one of the most important mysteries of physics today," CERN said, adding it will take several years to refine its studies.

The search for dark matter is moving ahead on two fronts. Last month, scientists at CERN announced they have more certainty a particle they observed last year is a Higgs Boson, a missing link in physics that would help them explain the makeup of universal phenomena, such as dark matter, that telescopes can't detect.

In that case, the data was gained using the $10.5 billion Large Hadron Collider, a 27-kilometer (17-mile) circumference particle accelerator buried on the border of France and Switzerland. CERN has had 10,000 scientists working on the research, in which billions of subatomic particles are hurled at each other at velocities approaching the speed of light.

--Editors: Bruce Rule, Angela Zimm

To contact the reporters on this story: Thomas Mulier in Geneva at tmulier@bloomberg.net Anna Edney in Washington at aedney@bloomberg.net

To contact the editor responsible for this story: David Risser at drisser@bloomberg.net; Reg Gale at rgale5@bloomberg.net