Physics professor Cleland did crucial work on Higgs boson particle

Bill Cleland

Bill Cleland, emeritus physics and astronomy professor, whose decades of work on the Large Hadron Collider was crucial to the discovery of the theorized but previously undetected Higgs boson in 2012, died Feb. 20, 2019.

“There was a period of 20 years of building the detector when people didn’t realize how important it was,” recalled departmental colleague Joe Boudreau. “A lot of his work was not recognized for how very important it was.”

Cleland had done his post-doctoral work as an experimental high-energy particle physicist at the Centre for Nuclear Research (CERN) in Geneva, Switzerland, and joined the international collaboration of thousands of physicists, known as ATLAS, in 1994 to build special particle detectors for CERN’s Large Hadron Collider, with the goal of discovering “the most exotic form of matter we have in the universe,” Boudreau said.

The multi-decade effort was “a task of enormous technical complexity — it’s probably the most complex machine ever built,” he said of the collider. Cleland developed the first layer of the detecting apparatus, the liquid argon calorimeter, where particles are caught, identified and their energy measured, which was critical to the Higgs boson discovery. “But he was a consultant on very many other issues that came up,” Boudreau said. Indeed, Cleland was drawn out of retirement to continue work on the project and was preparing it for future detection projects until recently.

In 2018, Cleland received two lifetime achievement awards, one from the ATLAS collaborators at universities and laboratories across the United States and the other from current and former liquid argon calorimeter project leaders within the international ATLAS collaboration.

Cleland joined the Pitt faculty as an associate professor in 1970 and became a full professor in 1978, spending more than 50 years at the University. Boudreau met Cleland when he joined the department in 1993. Cleland retired from his teaching role in 1999.

“He was renowned for being able to explain things very clearly,” Boudreau remarked. “If he met one on one with students, they were very happy.” Cleland also mentored a great many students, Boudreau said, as he read praise and remembrances sent recently to the department from all over the world.

“He had a very warm personality, a quiet sense of humor and was very diplomatic,” Boudreau added. While physicists can have large egos, he said that was not the case with Cleland: “He was very used to hearing people out, not being pushy,” in order to accomplish work that took decades to come to fruition. Boudreau recalled seeing Cleland with a group gathered around him in the office. “Everybody was listening to him. It’s at that point that I realized, wow, this is really an intellectual we have here.”

Wilfred Earl Cleland was born Aug. 10, 1937 in St. Francis, Kansas, growing up there and in Genoa, Texas. He earned his B.S. in physics from Texas A&M University in 1959, serving in its Corps of Cadets. He received an M.S. in 1960 and Ph.D. in physics in 1964, both from Yale University. At the start of his association with CERN, he was a NATO postdoctoral fellow (1964), a National Science Foundation postdoctoral fellow (1965) and a visiting scientist (1966-1967).

He began his academic career in 1967, as an assistant professor at the University of Massachusetts, receiving tenure as an associate professor there in 1969, before moving to Pitt.

In addition to his work at CERN, he also collaborated on experiments at Brookhaven National Laboratory in New York.

He is survived by his wife, Sigrid; two daughters, Janine Cleland and Brigitta Cleland-Hura; and five grandchildren: Astrid and Viviana Fiverson and Annika, Aiden and Kaelyn Cleland-Hura.

Memorial contributions are suggested to the University of Pittsburgh’s Physics Graduate Student and Visitor Resource Fund: contact Arthur Kosowsky, chair, Department of Physics and Astronomy, University of Pittsburgh, 100 Allen Hall, Pittsburgh, PA 15260 or send a note specifying the fund with a check directly to the Office of Institutional Advancement, 128 North Craig St., Pittsburgh, PA 15260.

A future memorial service is being planned.