The PS Booster hits 40

Many accelerators’ "round" birthdays are being celebrated at CERN these days – the PS turned 50 in 2009, the SPS was 35 in 2011, and this year it's the turn of the PS Booster to mark its 40th anniversary. Originally designed to accelerate 1013 protons to 800 MeV, it has far exceeded its initial design performance over the years.


The PS Booster in the 1970s.

Imagine the scene: a group of accelerator physicists staring expectantly at a monitor, when suddenly a shout of joy goes up as a signal flickers across the screen. Does that sound familiar? Well, turn the clock back 40 years (longer hair, wider trouser legs) and you have the situation at the PS Booster on 26 May 1972. On that day, beam was injected into the Booster for the first time. “It was a real buzz,” says Heribert Koziol, then Chairman of the Running-in Committee. “We were very happy – and also a little relieved – when the beam finally went all the way round.”

The machine, at that time run by the Synchrotron Injection Division under Giorgio Brianti and his deputy Helmut Reich, had the mission to increase the intensity that could be accelerated in the PS by a factor of 10. The Booster is still one of a kind today: four superimposed synchrotron rings, into which the beam from the Linac is successively injected. The four beams are then accelerated and eventually  recombined after extraction before entering the PS.

Prior to construction of the Booster, protons were accelerated up to 50 MeV in the Linac and injected directly into the PS to be accelerated up to 26 GeV. Adding the Booster allowed an acceleration of up to 800 MeV before injection into the PS. At this higher energy, the PS accepted an order of magnitude more protons, thus enhancing its potential for experiments and for the machines it was supplying with protons.

The PS Booster in 2012. The boxes around the 4 PS Booster rings (not visible) contain magnets: the green ones contain dipoles and the orange ones, quadrupoles. 

“By 1974, we had reached the full design intensity of 1013 protons per pulse,” explains Karlheinz Schindl, part of the original team and who later went on to become the group leader responsible for the Booster and its preparation for the needs of the LHC.

The Booster has since gone from strength to strength as a result of successive upgrades, and by the 1980s it was operating at four times the original design intensity. It has also developed an incredible versatility, able to adapt the structure and quality of its proton beams to supply both its sole direct user, ISOLDE, and to pass the different beams to the PS for further exploitation by all other proton facilities at CERN, including the LHC. It has also learnt to accelerate all kinds of ions.

“The magnets are pretty much the only original components left,” explains Klaus Hanke, today responsible for Booster operation and upgrade. “And we are currently preparing for the next massive upgrade. Having taken the machine from 800 MeV to 1.0 GeV and then to 1.4 GeV in the past, we are now looking at increasing to 2 GeV. We plan for the Booster to run for the whole lifetime of the LHC.”

To mark the 40th anniversary, the PS Booster team is planning a colloquium in the autumn and an accompanying Courier article. In the meantime, we can all blow out a mental candle for the Booster and wish it every success until its next major anniversary.

by Joannah Caborn Wengler