Giovanni “Gianni” Fiorentini (Seravezza, February 22nd, 1948 - June 18th, 2022) was an Italian physicist. His main interests were neutrinos and applications of Nuclear Physics to different disciplines, such as Astrophysics, Earth Sciences and Nuclear Medicine.

He graduated with honors at the University of Pisa in 1970. He also was a student and a PhD student at the Scuola Normale Superiore, where he served as a Research Assistant. From 1974 to 1986 he was a Researcher at the National Institute of Nuclear Physics. In 1987 he was appointed as Full Professor of Nuclear and Subnuclear Physics in Cagliari and moved to Ferrara in 1990. At the University of Ferrara he held various positions, including the Dean of the Faculty of Sciences and the Director of the Institute of Advanced Studies IUSS-Ferrara 1391. He represented the full professors of Physical Sciences in the National University Council and was a member of the Physics Committee of the National Research Council. Within the National Institute of Nuclear Physics (INFN), he served as a member of the INFN Board of Directors, Director of the INFN Department of Ferrara and then Director of the Legnaro National Laboratories. He also chaired the Consortium “Future in Research”, a private research organization.

Author of about 200 scientific publications, his research was on phenomenological aspects of interdisciplinary problems, often combining basic research with applications:

• Study of muonic atoms and muon-catalyzed fusion were performed in collaboration with Luciano Bracci and the group of Semen Gershtein and Leonid Ponomarev.
• Together with Nicola Cabibbo, Giorgio Parisi, Raffaele Tripiccione and others, he started the APE project, for the construction of the first super-computer dedicated to calculations of Quantum Chromo Dynamics.
• Research on stellar models and solar neutrinos with Vittorio Castellani opened in Italy a line of research on theoretical astro-particle themes.
• Together with Claus Rolfs and Marcel Arnould, he proposed a critical review of the nuclear astrophysics data relevant to solar neutrinos, which then developed as the Nuclear Astrophysics Compilation of REaction rates (NACRE).
• Together with Claus Rolfs, he proposed an underground laboratory for nuclear astrophysics (LUNA), which was built and exploited by INFN at the Gran Sasso.
• In collaboration with Luigi Carmignani, Gianpaolo Bellini and their groups, he has pursued an interdisciplinary research for the study of the interior of the Earth by means of geo-neutrinos.
• Together with Adriano Duatti, he has developed the project of a Laboratory of Radioisotopes for Medicine (LARAMED), a structure for research and production of radioisotopes at the National Laboratories of Legnaro.