Sam Ting's Alpha Magnetic Spectrometer was delivered to space in 2011 on the next-to-last space shuttle flight.
Sam Ting speaks softly and deliberately as he gets ready to deliver some juicy news to his audience. "You normally cannot hear me anyway," jokes the physicist at the start of a talk this past December at CERN, the particle physics laboratory near Geneva, Switzerland, while a technician fiddles with his microphone.
Ting may be soft-spoken, but few would call him retiring. Two decades ago, Ting persuaded funders to spend $1.5 billion to build the Alpha Magnetic Spectrometer (AMS). In 2011, NASA launched the 8.5-metric-ton magnet on the penultimate space shuttle flight and attached it to the International Space Station (ISS). Now he is capturing attention again, with a hint—buried at the end of his talk—that the AMS is finally delivering on the promise of its original name, when "AM" stood for "antimatter."
So far, the AMS has measured the masses and electric charges of some 90 billion particles that have passed through the magnet's maw. Nearly all of those are protons and helium nuclei, along with a smattering of electrons and nuclei of carbon, oxygen, and iron. A precious few are antiprotons and positrons: the antimatter counterparts of protons and electrons. To Ting, those antiparticles may be clues to the unseen "dark matter" that weighs down galaxies with extra gravity, although many astrophysicists regard them as the byproduct of humdrum galactic events.
Those antiparticles are not Ting's big news, however. At CERN, and again in a 16 February talk at the Massachusetts Institute of Technology (MIT) in Cambridge, where he has worked since 1969, Ting says that the AMS may have trapped a bigger and weirder form of antimatter. The AMS, he says, has seen a handful of candidate particles of antihelium-3, made of two antiprotons and an antineutron. In labs on Earth, physicists have made antihelium for a few fleeting instants, but no one has ever detected it in space.
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