LEIR commissioning successfully completed

An important milestone has been passed in the preparation of the injector complex to supply ions to the LHC experiments.

The Low-Energy Ion Ring - LEIR for short - has passed its first tests with flying colours. On 12 May, the ring that will accumulate lead ions for the LHC was shut down after seven months of tests (see Bulletin 44/2005). 'The commissioning phase was a resounding success,' enthuses a satisfied Michel Chanel, head of the LEIR construction project.

After several months of fine-tuning, the LEIR team has achieved its aim of producing the kind of beam required for first lead-ion collisions in the LHC in 2008. This involved creating bunches containing 230 million ions, in line with the specifications for those first beams. This success can be put down to the machine's outstanding design and components. 'It's a great achivement by all the teams involved in the machine's construction,' underlines Christian Carli, who was responsible for LEIR commissioning.

But it was not all plain-sailing throughout commissioning; one of the problems encountered was the beam's abnormally short lifetime. So when the machine was shut down in January, the equipment was upgraded, allowing fine-tuning work to be kept on schedule. Thanks to an excellent vacuum and electron cooler, inter alia, the teams managed to increase the beam lifetime to 14 seconds, way beyond the 3.6 seconds of the nominal LEIR cycle. After accumulation and acceleration, the beam was ejected and transported right up to the PS injection region.

The machine will be re-started in the autumn from the new CERN Control Centre (CCC). 'We will then be testing the injection, acceleration and ejection of these LHC ion beams in the PS,' explains Stéphan Maury who heads up the I-LHC project to install the injector chain that will supply lead ions to the LHC experiments. The following year, ion transfer into the SPS will be tested before the final link in the chain is reached - the LHC - in 2008.