The scientists working the overnight shift at CERN's Control Centre for accelerators had a reason to celebrate this morning. At 3:38 a.m. beams of protons were colliding with a luminosity of 1.01 × 1032, a milestone that the teams running the Large Hadron Collider had been working all year to achieve.
CERN Director General Rolf Heuer explained all in the message he sent today to CERN staff:
When we started running the LHC at the end of March, we set ourselves the objective of reaching a luminosity of 1032 by the end of 2010 proton running. Last night, we achieved that goal. The beams that went in at around 2:00am, were colliding with a luminosity of 1.01 × 1032 by 3:38am in both ATLAS and CMS, and had delivered an integrated luminosity of over 2 inverse picobarns to ATLAS, CMS and LHCb by midday today. It’s a great achievement by all concerned to reach this important milestone with over two weeks to spare. The remainder of this year’s proton running will be devoted to maximising the LHC 2010 data set and preparing for 2011 proton running before we switch to lead ions in November.
The significance of this milestone can’t be underestimated, since it is a necessary step on the way to the larger goal of delivering an integrated luminosity of one inverse femtobarn to the experiments by the end of 2011. That’s the amount of data we need to ensure that if nature has put new physics in our path at the LHC’s current collision energy, we’ll have a good chance of seeing it.
At the moment, we’re running the LHC with 248 bunches per beam in a configuration that allows us to go much higher. As 2011 proton running gets underway early next year we’ll continue increasing the number of bunches, since a factor of two or so more luminosity is still needed if we’re to reach our one inverse femtobarn goal. That, however, is for next year. In the meantime, the objective we set ourselves for this year was realistic, but tough, and it’s very gratifying to see it achieved in such fine style.
The LHC's first high-energy proton run will last for about two more weeks. A technical stop of a few days will follow the end of the historic run, and the accelerator complex will then be prepared to collide the LHC's very first beams of lead ions.