First results due from AMS

By Michael Banks in Boston

The first results from the $1.5bn Alpha Magnetic Spectrometer (AMS) are expected to be released in the coming two weeks, according to AMS principal investigator Samuel Ting.

Ting, who shared the 1976 Nobel Prize for Physics, was speaking at the 2013 AAAS meeting in Boston.

The AMS is a particle-physics experiment that sits on the International Space Station. It was first proposed by Ting in 1995 but had to overcome funding hurdles before it was finally installed on the ISS in 2011.

The AMS will search for an excess of charged particles such as positrons in an energy range from 500 MeV to 1 TeV. It will look at the ratio of positrons to electrons over this entire range – especially looking for a sharp peak in the ratio – and in different directions in space. It will then look at how this ratio changes to give any hints of dark-matter annihilation.

Such a peak in the number of such particles could signal the presence of neutralinos – a leading candidate for dark matter – or other candidate particles that are colliding with each other and emitting the charged particles.

So far the AMS has collected around 18 months’ worth of data – around 10% of the amount it expects to collect over its 20-year lifetime.  “Nothing has gone wrong so far,” adds Ting. “Yet it did take us some time to know how to work on the space station.”

Ting reports that the AMS has collected around 25 billion events so far, of which around eight billion are positrons and electrons. “The data are very clean,” he says. “No question they are events.”

The paper Ting and colleagues have written will look at data from 0.5 to 300 GeV, but he wouldn’t give participants any more information, sparking audible groans from the audience. “We have waited 18 years to write this paper, so want to make the final checks,” says Ting. “In two to three weeks’ time we should be able to make an announcement.”

Ting says that the paper may be submitted to Physical Review Letters, but was unclear if the collaboration would also be putting the paper on the arXiv preprint server. He adds that he may give a symposium at CERN to correspond with the paper’s publication.

So we will just have to wait and see.