BEYOND THE HIGGS BOSON WITH THE CMS COLLABORATION
Interview with Roberto Carlin, INFN researcher and professor of physics at the University of Padua, spokesperson for the international CMS (Compact Muon Solenoid) collaboration at CERN since 2018.

Since September 2018, Roberto Carlin has led the around 4,000 people - scientists, engineers, and technicians from all over the world - engaged in the CMS collaboration. The latter is one of the four big experiments of CERN’s LHC accelerator and was key to the Higgs boson discovery, along with ATLAS, in 2012. Since 2018, in addition to characterising the particles produced in the LHC, especially the Higgs boson, the collaboration has been dedicated to the development of the experiment upgrade. This is being done in view of the next, post-LHC phase, which will see the start of the High Luminosity LHC (HiLumi LHC) in 2027, the high-luminosity successor to the accelerator, which is currently in development. Weighing 14 tonnes, measuring 21 metres in length and 15 in diameter, CMS represents, together with ATLAS, one of the two big general purpose experiments dedicated to studying all the events produced in the collisions between the proton beams in LHC. The detector, which is cylindrical, is located at a depth of 100 metres along the LHC path and has a structure of concentric layers that enables the identification and measurement of the physical characteristics of the different particles produced: from the very accurate measurement of the traces of charged particles observed in the innermost part of the detector; to the measurement of their energy in the surrounding calorimeters; to the identification of the more evasive particles, the muons, detected in the outermost layer of the detector. Roberto Carlin started his scientific work in the early 1980s at CERN and at the INFN Frascati National Laboratories, later spending a long period in the DESY laboratory in Hamburg, where he worked on the ZEUS experiment, for which he was vice-spokesperson. Member of CMS since 2005, he contributed to the installation and starting-up of the muon detector, and to the management of the first phases of data acquisition. He was, in addition, coordinator of the CMS trigger and vice-spokesperson for the collaboration. Elected spokesperson in September 2018, Roberto Carlin will complete his term in August 2020.

From its inception, in 2008, the performance of the LHC has increased to the point of placing an unprecedented challenge before the experiments, in terms of the quantity of data produced by the LHC collisions. How have you approached this? It’s true, LHC is much higher-performing than expected, both in terms of luminosity and in terms of efficiency, and it is an excellent thing because it provides experiments ...

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