Pierre Adrien Piroué (1931-2020)

Pierre Adrien Piroué  (1931-2020)

(Much of this announcement is taken directly or indirectly from the 2001 Princeton University booklet honoring faculty members transferring to Emeritus Status. This eloquent article covers Pierre’s career in greater detail and is well worth reading.)


Pierre A. Piroué, Henry Dewolf Smyth Professor of Physics, Emeritus, passed away peacefully on Wednesday February 12, 2020, in Princeton Hospital after a brief illness. For over 60 years Pierre graced the physics department with his outstanding research and teaching, and unforgettable charm and wit. Though he retired in 2001, he remained active in research and created a highly popular and respected freshman seminar on the physics of music.  A talented skier and tennis player he loved his annual visits to Verbier in the Swiss Alps, and was a colorful, relentless presence on tennis courts on campus and at Constitution Hill.  Pierre is survived by his beloved wife of 65 years Marianne, son Olivier and his wife Teresa, daughter-in-law Beverly from his older son Nicolas, who predeceased him in 2004, and grandchildren Amanda and Andrew.

Born in 1931 in La Chaux de Fonds, heart of the Swiss watch industry, Pierre came to Princeton for graduate study in 1956 after graduating in physics and chemistry from the University of Geneva, and performing military service.  To his unpleasant surprise, even though married by then he was subject to the US draft.  Fortunately, Princeton worked out an arrangement whereby he could function as a Princeton graduate student while formally enrolled at the University of Geneva, where he received his Doctorate in 1958 for cosmic ray research performed under Princeton professor George Reynolds.   

After two years as a Princeton postdoctoral research associate with Val Fitch and a year back in Geneva as a CERN fellow, he joined the Princeton faculty in 1961 as an instructor in physics, advancing to the rank of professor by 1970.  He quickly became a world expert in fast electronics and particle detectors, and a leader in the ever-larger teams needed to conduct these experiments.  Pierre’s long and exciting career spanned the golden age of particle physics, which revealed a set of fundamental particles and force carriers from which theorists created a powerful Standard Model that relates all experimental observations and connect particle physics with the cosmology of the early universe.  To set the scale, Pierre’s first experiment was essentially a solo effort. His last, the gigantic CMS collaboration at CERN where the efforts of his Princeton group played a central role in the discovery of the Higgs boson in 2012, consisted of more than 3000 scientists.   

Pierre was a true “energy-frontiersman,” making sure to stake his claim at each new accelerator as it surpassed its predecessors. Among his experiments, four stand out. In the 60’s he conducted a sensitive search for particle-antiparticle asymmetry in K meson decays at the 33 Giga-electron volt (GeV) Brookhaven Alternating Gradient Synchrotron that was only superseded after 50 years.  In the 70’s he went to the Fermilab, where he and his partner James Cronin found an anomalously large yield of muons produced in 200-GeV collisions, signaling new physics and leading to the discovery of the charm quark two years later.  In the 80’s and 90’s his interest focused on LEP, a giant 100-GeV electron-positron collider being constructed in a 27 km circular tunnel at CERN in Geneva, Switzerland. Pierre led the Princeton group into the L3 experiment at LEP and its 10-year physics program, the highlights of which included discovering the detailed properties of the carriers of the weak force (W and Z bosons), and a set of exquisitely precise measurements that confirmed the consistency of the standard model, and predicted the mass of the Higgs boson, tantalizingly close but unfortunately just beyond the LEP’s capability.

LEP did not die in vain, however. Its tunnel now contains the world’s most powerful accelerator, the Large Hadron Collider (LHC), a 14-trillion-volt proton-proton colliding beam facility.  With characteristic foresight, Pierre secured a strong Princeton presence in this latest adventure, the CMS experiment, which discovered the Higgs Boson, and in upgraded form will remain Princeton’s flagship effort in particle physics for many years to come, as we search for dark matter, supersymmetry and other new physics beyond the standard model.

Pierre's teaching accomplishments are legendary, especially his bravura performances as lecturer and director of the largest course in the physics department, Physics 103-4, which he somehow transformed into one of Princeton’s top-rated courses. He performed this miracle by combining a latent acting talent with great organization and discipline. His lectures were simply great, and the course ran like a Swiss watch.  (This is not to disparage his upper-class courses, which were also always of the highest quality.)

After his retirement in 2001, Pierre remained active at CERN until recently, supporting his Princeton successors in CMS. However, he concentrated his enthusiasm and efforts on a brilliant novel idea in teaching: his Freshman Seminar on Physics and Music, described in the Princeton Alumni Weekly as “a Pied Piper-like lure for musicians.”  Lectures included theory and application, in a venue that resembled more a music studio than a classroom or laboratory.  Students, most of whom play an instrument, were encouraged to bring them to the 3-hour session, creating an exciting practical environment in which they could try out in real time the physics they were learning.   

Pierre will be fondly remembered, and sorely missed by his family, friends and colleagues.