Laurea e dottorato

Degree in Physics (1999)

Identificazione isotopica nei raggi cosmici con l'esperimento NINA su satellite - PDF

(Isotopic identification of cosmic rays with the satellite experiment NINA)

The NINA experiment was a satellite mission (1998-1999), designed to study low-energy (approximately 10-100 MeV/n) cosmic rays. With 32 planes of silicon detectors 380 μm thick, segmented in 16 strips, the reconstruction of both topology and energy release for particles entering the "telescope" was possible. Elemental and isotopic discriminations was achieved for low-Z nuclei, thanks to the dE-E technique. Galactic cosmic rays were selected from Solar or trapped particles by choosing the events gathered within the Polar regions in periods of Solar quiet. Only particles completely contained in the telescope were registered.
My work concerned the analysis of the isotope discrimination between ³He and ⁴He with the information on the energy loss for every crossed silicon plane. We could reconstruct the ⁴He mass with a standard deviation of 132 MeV/c². This value gives a negligible contamination of ⁴He in the ³He selection, the less abundant species (being 918 MeV/c² the mass difference between the two isotopes).
The ³He/⁴He ratio was measured for galactic cosmic rays in the energy range 20-50 MeV/n: it resulted (9.6 ± 1.6)%. This ratio is significant in astrophysics, since it is related to the mechanism of propagation of cosmic rays in the Galaxy, namely to the amount of matter traversed from the cosmic sources to the Earth.

PhD in Physics (2003)

Simulation of silicon microstrip detectors for a cosmic ray experiment - PDF

The PAMELA experiment was a satellite mission designed to detect antimatter in cosmic rays. The satellite carrying PAMELA was launched in orbit in June 2006. In the PAMELA spectrometer the tracking system was composed of six silicon microstrip detector planes arranged in a self-supporting structure, without material above or beneath the sensitive part. During many beam tests a spatial resolution of about 3 μm on the X coordinate (related to the track curvature) was obtained for silicon detectors with a strip pitch of 51 μm and one intermediate unconnected strip.
A simulation of the silicon microstrip detectors used in the PAMELA tracking system was done for the thesis. We simulated the collection on the strips of the charge generated in the silicon layer by ionizing particles, after the drift of the charge along the electric field lines. In this way the electrical signals obtained for every channel were equivalent to the signals arising in the read-out electronics as a consequence of a real particle in the telescope.
The simulation was very useful to completely understand the effect of different physical processes on the output signals. Moreover, the spatial resolution obtained with some methods of impact point reconstruction has been studied. We analyzed tracks orthogonal to the sensor and also inclined up to 20 degrees, which corresponds to the maximum angular acceptance of the PAMELA telescope.