8am: Yet another early morning after a late night. I am getting too old for this (some would disagree with the “getting”). The shifters this morning are the same as those from yesterday morning, who were unfortunate in that there was no beam throughout their shift. They were more fortunate today as the beam was on. But our data acquisition system was not in such good shape. In the middle of the night the system had stopped working. A Windows-based laptop that controls part of the system seemed to have spontaneously rebooted itself!
8am: Another early start – meeting the two physicists and taxiing them to the beam area to be on shift for the next eight hours. Both are at the same institute – NCU Taiwan – but, as is often the case in our field, only one is from Taiwan – the other is from India.
9am: We reconvened at the test-beam area. First thing on the agenda was a second visit from the safety service, who wanted to see if we could improve on the grounding of our system – to protect people from any possible chance of electrocution. The risk was already extremely low (and, in any case, people are not permitted near the equipment when it is running) but we still managed to improve things a bit.
5am: I drove my wife and kids to Geneva airport. They are leaving for ten days in the sun, in the knowledge that even if they were not going away, they would see precious little of me for the next week: it is test-beam time at CERN!
Yesterday was an exciting day! While many people were hunting for eggs in their gardens and enjoying a nice Easter-Sunday lunch, physicists and engineers from CMS congregated in their control room near Cessy in France to partake in their own hunt: for the first signs of particles from the LHC in the CMS detector for two and a half years. In the morning the LHC operators started to thread the protons beams around the 27km ring, sector by sector. They first tried with "beam 2", the anti-clockwise beam.
After a two-year hiatus, proton beams will soon start to circulate in the LHC and, in a couple of months from now, we will have the first collisions at 13 TeV, nearly twice as much as in the first run of the LHC back in 2010-2012. Many things have improved in the LHC, to allow this higher energy, but many things have also happened in the CMS detector too. Some changes and repairs of hardware have been made, along with many improvements to "firmware" - the computer programs embedded in the custom-made electronics that control the detector - and software.