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Low-energy antiproton project up and running

Physicists from eight countries held the first meeting in a project to explore the use of low-energy antiprotons as tools for investigating the nature of antimatter.

The meeting took place in Geneva on 28 September.

Elena, the Extra Low Energy Antiproton Ring, is led by the European particle accelerator alliance, Cern, having been approved by the organisation’s council in June 2011. It involves scientists from Canada, Denmark, France, Germany, Japan, Sweden, the UK and the US and will deliver its first antiprotons in 2016.

Project leader Stéphan Maury explained, “Elena is a new facility aimed to deliver antiprotons at the lowest energies ever reached in order to improve the study of antimatter.”

Elena will consist of a small decelerator ring that will be installed in the same building that houses Cern’s Antiproton Decelerator. It will slow antiprotons to under a fiftieth of the energy reached in the current facility, producing a 10- to 100-fold improvement in its antiproton trapping efficiency.

In the decelerator, antiprotons have to be slowed by passing them through a series of foils, a process that results in the loss of some 99.9 per cent of particles present at the beginning of an experiment.

“This is a big step forward for antimatter physics. Going to extra low energy increases the trapping efficiency for antiprotons, which will not only improve the research potential of existing experiments, but will also allow Cern to support a wider range of antimatter experiments,” said Walter Oelert, a leader in antimatter research at Cern and an active supporter of the Elena project.

Antiprotons were discovered in 1955 by Owen Chamberlain and Emilio Segrè from the University of California, Berkeley, for which they received the Nobel prize four years later.

Since then, these subatomic particles have been regarded as an important research tool. In the 1980s, they played a pivotal role in the discovery of the W and Z particles at Cern, which also led to the 1984 award of the Nobel Prize to the Italian physicist Carlo Rubbia and his Dutch colleague, Simon van der Meer.