The CERN Laser Ion Source

CERN has recently installed a heavy ion Linac, which injects a lead ion beam into the accelerator chain of PSB - PS - SPS for fixed target experiments of the quark-gluon plasma.

With the approval of the LHC it is foreseen to collide Pb-Pb beams at energies in the 1000TeV (centre of mass frame) range. In order to have a reasonable collision rate in the ALICE detector, the particle production rate of the injector chain to the LHC has to be dramatically increased from the level obtainable with the present scheme. This is the aim of the PIL (PS Ions for LHC) project.

The preferred route for this upgrade is to run the Linac at 10 Hz rep rate (as opposed to ~1 Hz today) and inject the beam into the Low Energy Ion Ring (LEIR) where it is cooled (the emittance reduced) before acceleration and injection into the PS.

Another scheme could be to use a Laser Ion Source (LIS) as a pre-injector to the Linac. This would allow the production of a short pulse length (~5 us) high current, high charge-state beam for injection into a synchrotron (PSB or LEAR). It is this scheme that is being studied as an experiment in the PS-PP group.

In 2002 (and the beginning of 2003) the following tasks were undertaken

1. Installation of a new 100J laser amplifier and configuring the full laser chain of the Master Oscillator, spatial filters, gas absorbers and power amplifier.
2. Transport and focusing of this beam onto the target.
3. Tests of the charge-states available from the plasma (with Pb and Ta).
4. Extraction of the ion beam and measurement of the current.

However, the decision was taken that from the end of March 2003, the study will be stopped at CERN. Thereafter, the equipment will be moved to ITEP (Moscow) where work can continue, to use the source for the TWAC ion accumulator.