Gianfranca De Rosa

Silicon Photo Multipliers Detectors Operating in Geiger Regime: an Unlimited Device for Future Applications

Photon detectors are indispensable in many areas of fundamental physics research, particularly in the emerging fields of particle astrophysics, nuclear and particle physics, as well as in medical equipment (i.e. PET), in physical check-ups and diagnosis as in-vitro inspection (Radioimmunoassay and Enzyme immunoassay as luminescent, fluorescent, Chemiluminescent Immunoassay), biomedicine, industrial application, in environmental measurement equipment (like dust counters used to detect dust contained in air or liquids, and radiation survey monitors used in nuclear power plants). In astroparticle physics, photons detectors play a crucial role in the detection of fundamental physical processes: in particular, most of the future experiments which aimed at the study of very high-energy (GRB, AGN, SNR) or extremely rare phenomena (dark matter, proton decay, zero neutrinosdouble beta decay, neutrinos from astrophysical sources)[3-7] are based on photons detection. The needs of very high sensitivity push the designing of detectors whose sizes should greatly exceed the dimensions of the largest current installations. In the construction of such large-scale detectors no other option remains as using natural media atmosphere, deep packs of ice, water and liquefied gases at cryogenic temperatures [8-13]. In these (transparent) media, charged particles, originating from interaction or decays of primary particles, emit Cherenkov radiation or fluorescence light, detected by photosensitive devices. Hence, for the improvement in the quality of the experimental results a particular attention should be paid to the improvement of photon detectors performances. In underwater neutrino telescopes (but this is applicable also to other experiments) Cherenkov light, emitted by charged leptons stemming from neutrino interaction, hits photomultipliers (PMT) situated at different distances from the track. This implies, that the response of PMTs should be linear in a very wide range from high illumination to the single photon. Another area of interest is the direct searches of Dark Matter in form of WIMPs: in these experiments it is exploited the scintillation properties of double-phase (liquid-gas) detectors, where primary and secondary scintillation light signals are detected by high-efficiency PMTs, immersed in cryogenic liquids or low temperature gases (89 K for the liquid argon) [14-17]. The next generation of experiments requires further improvement in linearity, gain, and sensitivity (quantum efficiency and single photon counting capability) of PMTs.

Two years of flight of the Pamela experiment: results and perspectives.

PAMELA is a satellite borne experiment designed to study with great accuracy cosmic rays of galactic, solar, and trapped nature in a wide energy range (protons: 80 MeV-700 GeV, electrons 50 MeV-400 GeV). Main objective is the study of the antimatter component: antiprotons (80 MeV-190 GeV), positrons (50 MeV-270 GeV) and search for antinuclei with a precision of the order of 10 −8 ). The experiment, housed on board the Russian Resurs-DK1 satellite, was launched on June, 15 th 2006 in a 350 × 600 km orbit with an inclination of 70 degrees. In this work we describe the scientific objectives and the performance of PAMELA in its first two years of operation. Data on protons of trapped, secondary and galactic nature - as well as measurements of the December 13 th 2006 Solar Particle Event - are also provided.

The vacuum silicon photomultiplier tube (VSiPMT): A new concept of photon detector. first feasibility results

The future astroparticle experiments will study both energetic phenomena and extremely rare events from astro-physical sources. Since most of these families of experiments are carried out by using scintillation phenomena, Cherenkov or fluorescence radiation, the development of photosensitive detectors seems to be the right way to increase the experimental sensitivity. We therefore propose an innovative design for a modern, high gain, silicon-based Vacuum Silicon Photomultiplier Tube (VSiPMT), which combines three fully established and well-understood technologies: the manufacture of hemispherical vacuum tubes with the possibility of very large active areas, the photocathode glass deposition and the recent Geiger-mode avalanche silicon photodiode (G-APD) for which a mass production is today available. This new design, based on G-APD as the electron multiplier, allows overcoming the limits of the classical PMT dynode chain. In this work VSiPMT first feasibility results will be presented.

The Time of Flight System and Trigger Electronics for the PAMELA Experiment in Space

The PAMELA experiment is a space-borne apparatus devoted to the study of the antiparticle component of cosmic rays. In addition The time-of-flight (ToF) scintillator system must provide the fast trigger to the experiment, the rejection of albedo particles, the possibility to distinguish electrons from antiprotons up to about 2 GeV and the measurement of the absolute charge of the particle. A readout electronics with wide dynamic range and a time resolution better than 100 ps is requested. The developed readout electronics for the PAMELA ToF system is capable of time resolution better than 50 ps with very low power consumption and has a dynamic range of about 12 bit. The developed board implements different trigger modes coming from the various subdetectors. The rate-meters of the ToF system and the logic to evaluate the live and dead time are implemented on this board, which also handles the busy signals generated by all subsystems. Since the system is destined to be carried in space, only radiation-hard (also qualified by us) components have been employed.

Positron identification in the ENUBET instrumented decay tunnel

The ERC granted ENUBET project aims at developing the technologies to reduce by a factor

A new high-gain vacuum photomultiplier based upon the amplification of a Geiger-mode p-n junction

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VSiPMT for underwater neutrino telescopes

10 the systematics in neutrino fluxes from conventional beams, allowing measuring the

A new Design for an High Gain Vacuum Photomultiplier: The Silicon PMT Used as Amplification Stage

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Study of PMMA materials for a digital optical module

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Vacuum Silicon PhotoMultipliers: recent developments

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