A few days back I told you things were going very well so far in 2012 at the Large Hadron Collider [LHC] — that not only had the increase in energy (from last year’s 7 TeV of energy per proton-proton collision up to 8 TeV) gone well but the collision rate (the number of collisions per second) had already been brought back up to last year’s level. And I pointed out that the current collision rate had been achieved using fewer bunches of protons than last year, which meant it could eventually be increased further, by putting more bunches in. But I didn’t know when they’d take that step — in particular, whether it would be anytime soon.
The proton beams at the LHC aren’t continuous; as of now, they consist of over a thousand bunches, each containing something like 100,000,000,000 protons. Two bunches are arranged to hit head on every 50 billionths of a second, and in each bunch crossing occur 10 to 40 virtually simultaneous proton-proton collisions.
Well, they did it the next day! Since Wednesday the number of bunches per beam has been about 1380, same as late last year, and the collision rate jumped up by over 25%, just like that! In fact they brought it even a bit higher (not sure exactly how) to within 15 – 20% of this year’s final target. And they’ve had some long runs, as long as nearly 10 hours, showing the accelerator remains very stable.
Three cheers for the accelerator physicists! Now the experimentalists just have to assure they can extract quality data from a firehose.