by Jiri Kral. Published: 16 December 2011

The 2011 heavy ion run ended on December 7th, leaving ALICE with a nice package of 132 million physics events and a little over 800 TB (3 PB before the HLT compression) of data.

The LHC machine broke records again and delivered an integrated luminosity of 140 ub^-1, which is roughly a factor of 14 more than during the 2010 run. It finished with 336 interacting bunches in ALICE and a peak luminosity maximum over 16 times last year’s record. The machine provided very good performance over the heavy ion run, though there were a few glitches after the magnet polarity switch. This was first caused by a vacuum accident leaving the machine without beams for almost 3 days and later by a MD period 2 days before end of run, after which no fill was held for longer than 2 hours.

The ALICE data taking efficiency steadily increased over the running period, peaking with 92% thanks to what is already well known as the Gilda effect. The overall ALICE data taking efficiency for the heavy ion period was around 73%. A big thanks belongs to the on-calls who were being woken up frequently during the nights and days.

The approved trigger mix was more rich this year, ALICE collected ~30M central triggers, 34M semi central, 8M Min-Bias, 50M muon triggers, 19M hight-pt triggers from the calorimeters, 8M ultra peripheral and 18k combined ultra peripheral+EMCal.

It was literally an electrifying experience to watch the experiment running from the ALICE Control Room. The collected data sample should provide sufficient grounds for many analyses and we are looking forward to the first exciting results.