After a successful period of important tests and calibrations in April, ALICE started taking physics data with minimum bias trigger at 3.5 TeV on 25 April. The LHC delivered stable beams up to 3 May and ALICE collected more than 200 million events at 3.5 TeV. During this period of stable beams, the LHC increased the number of bunches per beam from 480 to 624, and then to 760 bunches.
On 21 April, the LHC delivered a luminosity of 4.67 x 1032 cm-2s-1 which created a new world record surpassing the previous highest instantaneous luminosity of 4.024 x 1032 cm-2s-1 – which was achieved at the Tevatron collider, at the Fermi National Accelerator Laboratory.
This record was rapidly broken and re-broken, and the LHC delivered a luminosity of 8.84 x 1032 cm-2s-1 in the beginning of May.
On 3 May there was an access to the LHC for repair works which continued up to 4 May, with ALICE exploiting the situation by performing cosmic runs, collecting over 2 million cosmic events.
The LHC Machine Development program started on 5 May. This included several important tests and activities of the LHC, such as Radio Frequency single and multi-bunch instabilities, tests for new ATS optics, beam – beam limit, nominal collimation, quench tests, etc. In the meantime, the ALICE detectors were planning and organizing themselves for the technical stop which started on 9 May.
At the moment, the detectors are carrying out the interventions in the cavern according to plan. We are looking forward to a very stable and fruitful operation in the coming weeks.
Last but not least, on 30 April, ALICE restarted the 2011 barbeque sessions.