Collision time

This is a very quick update on the LHC status.  About two hours ago they had both beams circulating and crossing at the experiments (see for example the CMSexperiment tweet).  The experiments haven’t officially announced any collision events, though it is possible they have been recorded.  If I hear more I’ll update.

For links to many different sources of up-to-date information see the “Beam time” post.

This is a nice milestone, but it should be noted that for now the beams are only at injection energy.  This means that protons are accelerated to 450 GeV by a smaller (though still very impressive) accelerator, the Super Proton Synchrotron (SPS), and then are allowed to just coast around the ring of the LHC.  This is about half the energy of the Tevatron at Fermilab.

Update: event displays from the first collisions are now public.  There was a press release and a press conference.  I’ve attached some ATLAS event displays.