Is the author of numerous publications on experimental particle and astro-particle physics, and is best known for his development in the late 1970s of a new type of particle detector - the streamer tube. After having participated in the NUSEX experiment on proton decay in the Mont Blanc tunnel in the early 1980s, Iarocci was co-spokesman of the American-Italian MACRO experiment at the Italian Gran Sasso Laboratories. Director of the Frascati Laboratories near Rome from 1990 to 1996, Iarocci played an important role in the construction of DAPHNE, a very high intensity electron-positron storage ring designed for the study of the symmetry between matter and antimatter. He has been president of the I.N.F.N. ( Italian National Institute for Research in Nuclear and Sub nuclear Physics, 1998-2004) and President of the CERN Council (2004-2006).