After a three-year pause, antiproton physics gets under way later this year at CERN using the new Antiproton Decelerator ring. These articles look at the AD and its physics programme.
This year should see the start of physics with CERN’s new Antiproton Decelerator ring, marking the return of antiparticle physics to the CERN research stage three years after the closure of the LEAR low-energy antiproton ring in 1996.
The Antiproton Decelerator (AD) was built from CERN’s former Antiproton Collector ring, which was commissioned in 1987 to supplement the original Antiproton Accumulator (AA; meanwhile, elements of the AA have been sent to the Japanese KEK laboratory).
The task of the AD will be to take the antiprotons, which are produced by 26 GeV/c momentum protons hitting a target and selected at the optimum 3.57 GeV/c momentum level, and, as its name implies, decelerate them to much lower energies, using electron and stochastic cooling to control the beams.
Late last year the AD had a foretaste of particles the much more readily available protons, in this case. The antiproton debut is scheduled to take place soon after the restart of the CERN machines this spring, with the physics programme following in September.
On the menu are the ATHENA and ATRAP experiments, which will use magnetic trapping to manufacture atoms of antihydrogen. Following the first synthesis of chemical antimatter at LEAR in 1995, physicists have been eagerly awaiting a chance to revisit atomic antimatter country to see whether there is any difference between the behaviour of matter and antimatter.
Also on the menu is the ASACUSA experiment by a Japanese-European collaboration, which aims to continue the exploration of antiprotonic atoms atoms in which an orbital electron has been replaced by an antiproton.
