The last three years have been one of the most exciting periods in the life of CMS. Each year had its own share of important deadlines and expected deliverables, along with some unexpected challenges.
The last year of the first long shutdown of the LHC (LS1) was very intense, with several challenges in managing the programme of work, and keeping to and updating the schedule, in order to meet our goals. The list of major CMS achievements of this time include, among others, the completion of the fourth layer of the forward muon chambers, the overhaul of the DAQ , the completion and introduction of a brand new Timing Control system and the preparation of the first phase of the Level-1 Trigger upgrade. This work was carried out successfully despite unexpected difficulties: problems in welding the new Beryllium beam pipe and the repair of the Pixel Tracker were the top two that kept the management worried, awake, but were eventually addressed successfully.
The dawn of Run 2, with its eagerly anticipated 13 TeV, was a beautiful one for CMS: the detector was in great shape, with more active channels than at the startup, and with the upgrades promising extended performance. The successful commissioning of the DAQ and the first stage of the new Level-1 calorimeter trigger proceeded well, and all eyes were on the physics. With all systems “ready to go”, the well-known problem with the cryogenic system of our magnet decided to strike with vengeance. This was probably one of the worst threats to CMS (S: Solenoid) since its inception; everyone in CMS was in agony, causing many sleepless nights and putting a huge stress on our operations – not to mention our physics. Even the world outside was genuinely worried. A valiant effort by many people in CMS, led by Technical Coordinator Austin Ball, minimised the impact on our physics and in parallel prepared the solution to the cryogenics issue during the year-end technical stop (YETS) of the LHC. With the comfort granted to us by the happy ending of this story, we can even recall how people were impressed by the breadth and quality of our physics results at the end of 2015 and the winter conferences in 2016. The words of a very senior member of the CERN SPC put it best: “So, despite the magnet, the two experiments have the same results! Wow.”
Throughout the first two years of our mandate, CMS has had to share critical resources with the important work and deadlines that were demanded by the need to plan our future. A long and very intense process led to critical choices for the phase 2 upgrades and future. The Si-tracker geometry and the Endcap Calorimeter technology are the most visible decisions that were taken during the period. Still, much more work has taken place and the completion of our Technical Proposal for the CMS of the HL-LHC was the culmination of a gigantic effort that has required all the talent and goodwill of the whole collaboration. The intense discussions with the CERN oversight committees –– LHCC and RRB –– and the new request for a previously unforeseen Scope Document are the markers of the intense effort that led to the successful approval by the LHCC of our upgrade proposal.
The last year has seen its share of achievements: the carefully planned and fully successful cleaning of the cold box for the magnet has reinstated the full power of the CMS detector. In parallel, the full Level-1 Trigger upgrade was completed just in time for the ramping up in luminosity of the LHC. During this last period the unforeseen challenges have been the necessity to speed up the HE upgrade to cope with the faster-than-anticipated radiation damage and the amazing performance of the LHC that has seen peak luminosities of up to ~1.2 1034.
Most importantly, our fundamental output, namely our physics results and the publications we generate, are of the highest quality and remain a justified source of pride for us all.
From a purely personal point of view I will never cease to marvel at the strength of the CMS collaboration: the true reasons for our success are to be found in the talent, experience, dedication and perseverance of CMS people. I would like to extend personal thanks to the coordinators and project managers who have put in their absolute best in the past few years. A special thank goes to Kerstin and Paris who have been sharing a lot of the load during these years. More so, I would like to thank everyone in CMS for making this collaboration all that it is today. I believe our future is bright.
— Tiziano Camporesi, CMS Spokesperson, Jan 2014 – Aug 2016
Related: Profiles of the new CMS management (2016–2018)