Suddenly, so much unexpected as disconcerting, the sad news came to us at the Legnaro Laboratory and immediately after addressed to the Alice and INFN communities: Luigi Vannucci, our friend and colleague, passed away , on Friday April 18 , just during a cardiac test, leaving all of us completely astonished and distressed. His death has particularly shocked all those who had the chance to really know and love him as a physicist and as a man.
Luigi Vannucci obtained his degree (the “laurea”) in Physics in 1982 at the University of Padova, discussing with me a thesis on the realization of an apparatus to detect the products of heavy-ion induced reactions in view of the first experiments to be performed at the 16 MV Tandem Accelerator, the first heavy-ion facility just installed in Italy. Already in 1983 he was engaged as permanent Researcher at the INFN-National Laboratory in Legnaro, under my direction. The first part of his scientific career was therefore concentrated in the investigation of the reaction mechanism of the heavy-ion reactions, particularly in the region of medium-mass nuclei (A around 100), at colliding energies of 1.5 to 3 times the Coulomb barrier with the aim at studying the variety of dissipative phenomena; interesting results were found showing the evidence of new intermediate mechanisms between the fission (or quasi-fission) and deep inelastic processes (FUFI-EVA experiment). His precious and competent collaboration was immediately recognized and greatly appreciated during the evolution of the various experiments performed at the Tandem, namely:
- a systematic investigation of the dissipative processes with the production of more than two massive fragments in the final state, at low bombarding energies (5.6 A MeV) pointing out the presence of two different mechanisms producing three-body final states, a binary sequential splitting and a prompt breakup in three aligned fragments (STARTREC);
- the study of the reaction time of the fusion-fission processes in different colliding nuclear systems by using the crystal-blocking technique, showing that such times are much longer than predicted by a simple fusion-fission model and should include post-scission evaporation processes (TIMEO-BOBET);
- the search of quasi-molecular resonances in heavy-ion systems formed at energies near the Coulomb barrier (TRITAN-QM), finding evidence of the presence of such door-states not only in the light-mass region (around A=50), but also in some medium-mass systems (A near 100);
- the study of the dynamics of excited medium-mass nuclei at bombarding energies of 12-13 A MeV, by measuring the gamma-charged particle coincidences following the production of Giant Dipole Resonance in the Cesium nucleus from two different entrance channels with different mass asymmetry, showing the presence of pre-equilibrium configuration (GARFIELD).
Starting from the 90’s, when I suggested to some of the members of the group (P. Boccaccio, L. Vannucci, M. Lombardi), to move to CERN and join the OBELIX collaboration already active in performing interesting experiments, concerning also the nuclear behaviour in the interactions with low-energy antiprotons at the LEAR facilty, Luigi was one of the more convinced of the interest of forming a special Legnaro group engaged in a CERN programme. The contribution of the group to the achievement of important results concerning the meson spectroscopy, the annihilation dynamics to determine the hadronic branching-ratio and the study of the annihilation processes on nuclei as compared with that on nucleons, so as the measurement of the antiproton stopping power in atomic targets (Barkas effect), was particularly appreciated, especially for the realization of a vertex detector (the SPC,”Spiral Projection Chamber”) thanks also to the qualified participation of Luigi.
Moreover, the experience acquired with heavy ions and the possibility to make a jump into the domain of relativistic and ultrarelativistic ion collisions, was the main argument to maintain our presence at CERN and join the Padova group (M. Morando, F. Antinori, A. Dainese) in the Italian participation to the experiments at the SPS devoted to the search of signatures of the QGP (Quark Gluon Plasma). The experiment (which gave, together with the J/Psi suppression, already some positive indication) concerning the Legnaro participation with Luigi as a group leader, was the NA57 dealing with the measurement of the production of strange particles in p-Be, p-Pb, Pb-Pb collisions at 40 and 138 A GeV, by using a telescope formed by silicon pixel and silicon strip detectors, a matter which became very familiar to Luigi and that was quite appreciated later by the ALICE collaboration, namely in the Silicon Pixel Project.
In fact, as I think, it is his strong involvement in the ALICE program and, even more, in the ALICE family, that consecrated his maturity as a qualified physicist and as a research leader; at LNL he has been not only the group leader but a sort of factotum, assuming any responsibility in the participation to the various activities established by the ALICE Collaboration Board and in the contacts with the Padova group and CERN.
At Legnaro we should remember also the various duties and responsibilities he accomplished as a Coordinator of experimental set-ups at the Tandem Laboratory, as a member of the Advisory Committee of the Research Division, as a Responsible of the Library and Documentation Service, as a Coordinator of the promotion of the scientific culture and as a member of many Conference Organizing Committees. Moreover he was also involved in teaching activities on General and Nuclear Physics, at the Padova University.
Remembering Luigi and his personality not only as a collaborator and as a friend since the time he went to Legnaro, but especially as a very human person of invaluable qualities, is certainly a duty we have to accomplish all together as members of a large scientific community with the consciousness of a great loss: his team and solidarity spirit, his admirable and intelligent discretion together with an exceptional goodness of heart.