GENEVA, SWITZERLAND – It’s been a busy and record-breaking week at Cern, the European Nuclear Research Centre on the French-Swiss border, with LHC (Large Hadron Collider) researchers achieving a significant milestone and elusive antimatter held for 1,000 seconds for the first time.
Trapping antimatter for longer opens new research vistas
“The Alpha experiment at Cern reports that it has succeeded in trapping antimatter atoms for over 16 minutes: long enough to begin to study their properties in detail. Alpha is part of a broad programme at Cern’s antiproton decelerator investigating the mysteries of one of nature’s most elusive substances,” the organization reports, following publication Sunday 5 June of the news in the scientific journal Nature (article free online).
Nature in November 2010 reported on Alpha’s capture of antimatter then, saying it was the first significant milestone in the field since 2002, but this week’s report takes the research work to a new level. “For physicists, a bit of antimatter is a precious gift indeed,” said the November Nature report. “By comparing matter to its counterpart, they can test fundamental symmetries that lie at the heart of the standard model of particle physics, and look for hints of new physics beyond. Yet few gifts are as tricky to wrap. Bring a particle of antimatter into contact with its matter counterpart and the two annihilate in a flash of energy.”
The new achievement raises the question of how long anitmatter can be held, say Cern scientists, and it opens new research possibilities.
It is the “first measurement of the energy distribution of trapped antihydrogen, which, coupled with detailed comparisons with simulations, provides a key tool for the systematic investigation of trapping dynamics. These advances open up a range of experimental possibilities, including precision studies of charge–parity–time reversal symmetry and cooling to temperatures where gravitational effects could become apparent.”
The longer time lets the antiatoms to sink into their ground state, an important advance for researchers because it allows them to investigate charge-parity-time, or CPT symmetry. Cern notes:
“Symmetries in physics describe how processes look under certain transformations. C, for example, involves swapping the electric charges of the particles involved in the process. P is like looking in the mirror, while T involves reversing the arrow of time.
“Individually, each of these symmetries is broken – processes do not always look the same. CPT, however, says that a particle moving forward through time in our universe should be indistinguishable from an antiparticle moving backwards through time in a mirror universe, and it is thought to be perfectly respected by nature. CPT symmetry requires that hydrogen and antihydrogen have identical spectra.
“‘Any hint of CPT symmetry breaking would require a serious rethink of our understanding of nature,’ says Alpha spokesperson Jeffrey Hangst of Aarhaus University. ‘But half of the universe has gone missing, so some kind of rethink is apparently on the agenda.'”
LHC collision rates increased 10-fold in May
The LHC, a massive machine that runs 100 metres underground below Geneva and the border area in France, is also back in the news, with the team that runs experiments reaching 1,092 bunches on a beam Sunday 29 May, a new record. The collision rate has increased 10-fold in the past month, says Cern.
The LHC is a particle accelerator used by physicists to study the smallest known particles – the fundamental building blocks of all things. The more collisions at the four points around the giant machine, the more data there is for researchers.
“I think this is beyond the wildest dreams of everybody, that we could have done it this early, in the second year of operation,” Mike Lamont, a member of the team says in a video published on the Cern site. The system is stable, he adds, and the team says it can now concentrate on delivering the larger number of collisions that investigators need in order to spot the “needle in a haystack” incidents they are seeking.