Just saw this from Tommaso Dorigo, which made me realize that I should get to work and write a blog posting before the CERN press office people wake up. The big news today is that the first collisions at a record energy higher than that of the Tevatron have occurred, marking a first step into new territory past what has been the energy frontier in HEP for a very long time. Two beams of two bunches each were successfully ramped up to 1.18 TeV, and although one of the beams was lost after a while, before that point some collisions at a total energy of 2.36 TeV were observed. An event display from ATLAS is here.
Over the next few days, the main objective of the beam commissioning team is to try and increase the intensity per bunch and provide a large number of collisions at 450 GeV/beam to the experiments. They’ll also continue tests in which they ramp up the energy to 1.18 TeV/beam, and if all goes well should be able to provide the experiments with an equally large number of collisions at that energy. The experimenters are gleeful about finally having real data to play with. CMS has publicly announced the re-discovery of the pi-zero, and I assume that by now they’re working their way through the 1950s, already rediscovering kaons and other particles with strange quarks. If they manage to get a significant amount of data at 2.36 TeV, there must be some sort of cross-section they can measure at an energy that just beats out the Tevatron, although with this size of a collision sample, it won’t be one that anyone cares much about…
Beam commissioning work for 2009 should end on December 16, and the accelerator complex will be shut down over the holidays, re-starting January 4. During January the LHC will go back into hardware commissioning mode, with a month-long plan to commission the new quench protection system in all sectors, allowing operation at 3.5 TeV/beam. The injectors are supposed to restart on February 5, LHC beam commissioning restarting on February 8. The way things have been going, they may have at least some 7 TeV collisions happening quite quickly after that.
Update: This morning again a pair of 1.18 TeV beams were stored and brought into collision at the LHC. This time CMS as well as ATLAS is publicly saying that collisions were seen, with event displays here. CERN’s twitter feed is saying over a million collisions at 900 GeV, 50,000 at 2.36 TeV. Still no press release from CERN gloating about how they now are doing physics at higher energy than Fermilab.
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