Honorary Fellows: Professor Sir Tejinder Singh Virdee

Professor Sir Tejinder Singh Virdee completed his PhD at Imperial College London, after which he was awarded a CERN Fellowship in 1979 on the NA14 photoproduction experiment. There, he built a large multi-cell Cerenkov detector. Following NA14, he joined the UA1 experiment at the CERN proton-antiproton collider, where he invented a novel technique of collecting light using wavelength-shifting fibres embedded in plastic scintillator.

In 1990, Virdee and colleagues started planning the CMS experiment at the Large Hadron Collider (LHC). Since 1991, he has played a crucial role in all phases of CMS. This has covered conceptual design, intensive R&D, prototyping, construction, installation, commissioning, data-taking and physics exploitation. Virdee was the driving force behind many technology decisions in CMS, especially for the calorimeters. He proposed the choice of lead-tungstate scintillating crystals coupled to then-novel silicon avalanche photodiodes for its electromagnetic calorimeter. He pioneered the detection of the Higgs boson via its decay into two photons, for which the lead-tungstate calorimeter was optimized. This played a crucial role in the discovery of the Higgs in July 2012, in the analysis of which Virdee was deeply involved.

The CMS hadron calorimeter utilises techniques Virdee had invented earlier in UA1. Beyond calorimetry, he drove many changes during the construction of CMS, including the switch to an all-silicon tracker and the redesign of the electronics chain for the electromagnetic calorimeter.

Virdee helped expand the CMS collaboration by bringing in new collaborators, soliciting funds and negotiating in-kind contributions, requiring frequent interaction with institute leaders, heads of universities, heads of funding agencies and government ministers in many countries. He was deputy leader of the collaboration in 1993–2006 and was then elected leader in January 2007 for three years. He oversaw the final stages of construction, installation and first collisions at the LHC.

The next stage of LHC, the High-Luminosity LHC, requires major upgrades to CMS, including the endcap calorimetry. Virdee conceived a novel technique using a large area of silicon sensors with fine segmentation and precision timing. Such developments will undoubtedly find application in the next generation of collider experiments, in the planning of which Virdee continues to be an important figure.

Virdee's contributions to particle physics, particularly at the LHC, have been both immense and sustained over decades. He continues to provide both innovative ideas and inspiring leadership and has also been an advocate and supporter of projects to improve the opportunities for many to study and pursue a career in physics in sub-Saharan Africa.