Historical introduction

Historical introduction

The Section of Fundamental, Nuclear and Elementary Particles Physics of the Department is also the center of the National Institute for Nuclear Physics, I.N.F.N., through the Brescia CONNECTED GROUP.
This works on the base of the convention stipulated with the Universita’ Statale di Brescia in 2002 and represents the acknowledgment of the National Agency for this field of Physics to the research work in the field of the Nuclear physics and Elementary Particles carried out by Prof. Evandro Lodi Rizzini and various collaborators from academic year 1980-81, when the Università Statale di Brescia had not yet been instituted and the Faculty of Engineering was connected with the Polytechnic of Milan.
In academic year 1980-’ 81 the activity at CERN (European Organization for Nuclear Research) in Geneva was started.
The first experiment (PS179), developed within an International Collaboration, marks the beginning of the search in the field of the Nuclear Physics for the measurements of the processes of the annihilation of Antiprotons on Nuclei. This field is moreover the object of the Search that always to the CERN of Geneva, has been approved from the Research Board of the Center the 2 june 2005.
From some hundreds of Mev of experiment PS179, the antiprotons initial energy will decrease to less than 1 keV with the new experiment ASACUSA (AD3), with a jump of five orders of magnitude in reducing the energy of the particle projectile (Antiproton).
After these 25 years of search in this field, then the group will achieve to measure fundamental physics quantities in the process of annihilation of Antiproton on Nuclei for values of its kinetic energy corresponding to the possible starting of capture by Atoms and Molecules.

Annichilazione di un antiprotone su nucleo di neonIn the famous photogram filmed in 1983 with the Streamer Chamber of PS179 Collaboration, it is possible to see the annihilation of the antiproton on a neon nucleus inducing the emission of a positive pion, π+, with the successive decay in a positive muon, μ+, which decays in the positron, e+. The three particles are clearly visible from the succession of their tracks which appear as curves lines since these charged particles move in an magnetic field (intensity = 0.5 tesla) orthogonal to the plane of the figure. This photogram introduces to the search in the field of Elementary Particles undertaken from 1985 within of the international Collaboration PS201, OBELIX, having for main goal the characterization of the possible particle made of only gluons (mediators of the force between quarks) or of gluons and light quarks formed in the antiproton-proton annihilation.
This last search has terminated in 2004 with important results and has been ATHENA apparatuscharacterized by the proposed innovative choice from Prof. Lodi Rizzini to use various hydrogen targets at very different densities to obtain the necessary information from all possible the various channels of annihilation of the antiproton at rest on proton.reconstruction of an anti-hydrogen candidate event recorded in August 2002
This methodology has carried the group to begin the activity in the field of the Atomic Physics, activity that would have lead to the Hydrogen Antiatom production still at CERN of Geneva in August 2002, for the first time in the science history, thanks to International Collaboration AD1 called ATHENA.
Prof. Lodi Rizzini has been the responsible of the Italian part of this Collaboration from the beginning, in 1995, until to 2001.

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