Obituary of Sergio Peppino Ratti

Sergio Peppino Ratti passed away on September 10, 2020 in Pavia. He was an experimental physicist and professor emeritus at the University of Pavia in the Department of Physics and in INFN.

Sergio Ratti was born in Garlate (Lecco) on September 5, 1934. He graduated in Physics in 1957 from the University of Milan where he then became assistant professor (1958-1959) and associate professor (1960-1972). He became full professor in Experimental Physics at the University of Pavia in 1972, a position he held until retiring from teaching in 2006. He spent several extended periods in the USA, first at Northwestern University in Evanston (IL), and later at Fermilab (Batavia IL) where he was a permanent visiting scientist, a role he also played at CERN.

His research activity started in the '50s in Marcello Conversi’s group which included fellow student Carlo Rubbia, studying the physics of elementary particles. Some of the highlights of his work include muon physics, weak interactions, the decay of resonant states into pions; multi-particle dynamics, the first experiments on jets; neutron-antineutron oscillations at the Triga Mark II reactor of the University of Pavia; production and decay properties with lifetimes measurements of charmed mesons and of barions, especially the primordial neutron; the interpretation of multi-particle production in terms of multi-fractals. Beginning in 1994, he was involved in the development of the Compact Muon Solenoid (CMS) detector, later installed at the Large Hadron Collider (LHC) of CERN leading to the discovery of the Higgs boson. His research also stretched into industrial applications and social issues, such as the development of Resistive Plate Counters (RPC) for Positron Emitting Tomography (PET) and the application of multi-fractals to the dynamics of environmental pollution from dioxin after the Seveso disaster (1976).

Sergio had leading roles in national and international organizations, in particular within INFN and the Italian Ministry for University and Research, where he was as a member of the National University Council (CUN) since 1999. He founded the Doctorate in Physics in Pavia and was among the founders of the PhD system in Italy (1981), being a strong advocate of doctoral education to promote advanced research and scientific innovation in the country. He was coordinator of the Doctorate in Physics in Pavia continuously from 1981 until 2006, as well as the director of doctorate programs of the University of Pavia from 1981 to 1990. In 2006 he was appointed as the first Director of the newly founded Graduate School of the University of Pavia, and was among the first promoters of the internationalization of Italian research programs.

Sergio Ratti educated generations of students in elementary particle physics and accompanied many of them through the doctoral program and beyond. He firmly asserted the value of the freedom and autonomy of graduate student’s research, as well as the importance of general culture and unitarity of Physics. He was always in a good mood, very active and sporty, and was always able to engage colleagues and students, with his witty and self mocking humor. Sergio left a stable footprint with his vision for the University’s research and its PhD program. The Physics Department remembers him for his vast contributions to elementary particle physics and for his generous and tireless activities as an educator, researcher, and organizer.