Right now, they’re letting the proton beam stream farther and farther through the LHC, stopping it at intervals with beam-dumps for safety. Minutes ago, the beam passed half-way around the ring, through the CMS detector (and now beyond CMS). I hear that the CMS trigger rate is showing something…
The inner CMS tracker has been turned off (no high voltage, no read-out) for protection. But the outer muon detectors, farther from the beam and less sensitive to radiation, should be on and taking data. Meanwhile, I’m putting the finishing touches on the software to use these data for alignment.
Happy birthday, Greg!
Update: the beam has gone all the way through! It all happened much quicker than I would have expected. They went step-by-step through each sector, saw a little bit of wiggling in the parts that were new territory, dumped the beam, started again, and apparently that was it.