## Friday, 6 April 2012

### LHC back online for 2012

Yesterday, CERN announced that the proton-proton collisions are again underway at the LHC, for the first time since last year. One quantitative change is that the machine is now accelerating each beam to $4$ TeV per proton, compared to $3.5$ TeV in 2011. (For those who might not know, $1$ TeV is equivalent, by Einstein's famous relation $E = mc^2$, to approximately one thousand times the mass of a proton.)

This year could be a very significant one for particle physics. If the Higgs boson really is sitting at $\sim125$ GeV, then its discovery is likely to be announced, and if low-energy supersymmetry is part of the real world, then we might hope to see at least the first evidence of it.

It is probably a good time to write something about what really goes on in proton-proton collisions, and why extra energy and 'integrated luminosity' are so important. That will have to wait until later though, because right now, my wife and I are heading into central Oxford to check out the street food festival, and do some shopping.