The clearest sign of the summer coming to an end is when September rolls in and the school year starts again. Eventually fall officially starts, this year it was on September 23. The Fall CMS week therefore was technically not in Fall because it ended on the last day of summer September 22 but it had all the signs of people getting back into it and making plans for after the summer. My flight to Geneva went really well sleeping for a good fraction of it after gazing at the beautiful landscape from above.
The W mass analysis which is one of the main activities in our group did not make it to pre-approval during the summer because of various complications that had arisen but we were set ‘come hail* or high water’ to get the pre-approval done during the Fall CMS week. This is at least what Josh Bendavid said a few weeks before. I had booked my flight after said quote, because I wanted to be in the room when it finally came to the first step in getting a CMS result on the W mass.
CMS has never published a result on the W mass (first data were taken in 2010). Given the present situation with ATLAS having published already their second much improved result and LHCb putting a good measurement forward already and the evident discrepancy with the CDF measurement, CMS has been under a lot of pressure to come out with its own measurement. The PPC has been working on this analysis seriously for a long time now and finally there seems to be a good enough result to come out and show what we have. The pre-approval went as expected with a long very good talk** masterfully presented by Kenneth Long (MIT) and a long list of questions and answers. CERN’s main auditorium was still well populated even at 8pm when finally the audience ran out of questions and the general discussion points about the way forward died out. Kenneth took care of most of the questions, but Josh jumped in on occasion with details of the techniques.
After the talk the PPC people at CERN went to celebrate the occasion at Luiga’s and decompressed and shared their thoughts on the future, past and completely unrelated topics. In short a very nice get together with good food and great company.
To top off my time at CERN we visited the ALICE silicon lab, where the ITS2/3 silicon wavers are tested. Gian Michele Innocenti our new MIT Heavy Ion junior faculty hire lead the tour that was followed by Loukas Gouskos (Brown), Mariarosaria and myself. There was unfortunately no bent sensor around to look at but we looked at the setup and got a very nice summary of the ongoing work. I think this is a great topic for the FCC-ee detectors because it seems that the rate is consistent with the possibility to air cool the detector at FCC-ee even at the Z pole.
Our first study should include:
- What is the radiation environment at the different stages of the FCC-ee (Z-pole, WW threshold, ZH production peak and top-pair production threshold)?
- Is it feasible to build a CMOS MAPS air cooled pixel detector for these conditions?
- Can we use ‘smart’ pixel technology in FCC-ee?
- Who is already working on this detector concept for the next e+e– machine?
Overall, the visit to CERN for CMS week and more was a full success, W mass was pre-approved, of course with plenty of conditions, and the silicon lab visit gave a great opportunity to talk about silicon detecotr plans for the future at FCC-ee for example.
* The original version says ‘come hell or high water’ but we thought this sounded a little too extreme.
** Only accessible by CMS members.