Protons have not only entered the LHC, but they have travelled through one of the experiments, ALICE, to a point part-way between ALICE and CMS. On the first try, the protons threaded through all the dipole magnets and appeared on target at the IP3 beam-dump.
Here’s the spot of protons, as seen by the beam-TV at IP3:
Full details are available on the LHC Injection Test webpage.
Meanwhile, CMS has entered more or less full-time data-taking mode. Until recently, we had been mostly installing detectors and taking cosmic ray data intermittantly, but now we are primarily taking data and closing up the detector. This week, we started our fourth major cosmic ray run without a magnetic field, in which charged cosmic ray muons appear as straight tracks through the detector, and soon we will turn on the magnetic field so that the tracks are curved with a radius inversely proportional to their momenta. In addition to bending muon tracks, it will tug our five-story iron endcaps so strongly that they will bend a few centimeters in the middle, with a force about 5 times their weight. Therefore, all components must be completely closed and bolted into position, closing off access to the inner detectors. Half of the detector is already closed.
This is it! It’s finally happening! More updates later.