Catálogo de publicaciones - libros

We review the main experimental results on neutrino oscillations obtained with man-made neutrino beams. Particular attention will be devoted to past-generation experiments which were based on conventional neutrino beam from proton acceleration and from nuclear reactors.

In this paper a brief review of the research for neutrinos from natural sources, namely solar neutrinos, neutrinos from the Earth (so-called geoneutrinos) and Supernova neutrinos is presented. Emphasis is given to established facts and to future measurements in experiments in operation or planned.

Thanks to recent data about the Cosmic Microwave Background (CMB), Large Scale Structures (LSS) and also Type Ia Supernovæ (SNe), cosmology has become the most sensitive probe of some neutrino properties and a very sensitive probe of others, including non standard ones [–]. On the issue of masses, cosmological observations play the dominant role nowadays: oscillation experiments test squared-mass differences, and other means of probing the absolute mass are less sensitive. On the other hand, cosmology may have an even deeper connection with neutrinos, being at the very origin of their mass, according to the proposal of Mass Varying Neutrinos (MaVaNs) [].

After about 70 years since the was given to light, after the marvellous successes of the and about 50 years of neutrino experiments . . . we still miss one of the more fundamental information concerning the character of neutrinos, and still “” an almost unique “”. If Neutrinoless Doube Beta Decay ((0)) exists the correct form of the theory is the one in which the is a massive Majorana particle identical to its antiparticle. If (0) does not exist — and if this is not the result of accidental “cancellations” — is a massive Dirac particle. Double Beta Decay is the only spontaneous decay that lead some unstable nuclei to a lowest energy isomer. In the decay two electrons are emitted transforming two neutrons into two protons. If the decay proceeds like two simultaneous beta decay two neutrinos are emitted toghether with the electrons but if is a Majorana particle the decay can proceed also through the exchange of a virtual and the emission of just electrons. Unable to detect the eventually emitted neutrinos the only signature that the experimentalist can search, to distinguish between (2) and (0), relies in the 2 electron energy spectrum: the sum of the electron kinetic energies is fixed at the -value in the (0) (the nuclear recoil is negligible) while it has a continuum probability distribution, zeroing above the -value, in the (2).

In this talk we discuss (1) which neutrino parameters, to be measured in experiments, have the deepest impact on the theory; (2) what are the possible contributions to neutrino mass from physics beyond the Standard Model (SM); (3) how to introduce a family symmetry which describes lepton flavor; (4) how to embed neutrino data within a grand unified framework.

Future detection of a supernova neutrino burst by large underground detectors would give important information about the supernova matter density profile and unknown neutrino properties, due to the effects of flavor oscillations in the supernova envelope. We mainly discuss the detectability of signatures associated to the shock-wave propagation in observable neutrino signals. We also investigate the effects of possible small-scale stochastic matter density fluctuations in the wake of supernova shock waves. We find that such fluctuations can partly erase the shockwave imprint on the neutrino event spectra.

We briefly review the concept of CP violation in the leptonic sector, focusing on several theoretical aspects concerning the possibility of measuring the CP phase at future neutrino facilities.

High energy neutrinos are considered optimal probes to identify the sources of high energy cosmic rays. Many indications suggest, indeed, that cosmic objects, where acceleration of charged particles take place are the sources of the detected UHECRs, the same sources should also produce high energy neutrino fluxes. Indeed, or interactions responsible for > TeV neutrinos and rays fluxes, are expected to occur in several astrophysical environments. In Supernova Remnants (SNRs) protons, accelerated through Fermi mechanism, can interact with gas in dense SN shells or molecular clouds, producing both neutral and charged pions. Decay of neutral pion originates gamma rays. The observation of ≃ 10TeV gamma rays from Supernova Remnant RXJ1713.7-3946 claimed by CANGAROO [], seems to validate this hypothesis, but the result is still under discussion. The neutrino flux, produced by charged pion decay, is expected to be similar to the hadronic high energy gamma rays one. Results from the HESS air Čerenkov Telescope, concerning the observation of TeV gamma ray from the Sgr A* region (the Galactic centre), show an ∝ ray spectrum that could be originated by hadronic interactions, an interpretation which also implies the production of intense high energy neutrino fluxes []. Photo-meson () interactions can occur in astrophysical environments that show dense low energy photons fields: microquasar jets, AGNs and in GRBs are examples.

We present a brief introduction to the physics of Ultra High Energy Cosmic Rays (UHECRs), concentrating on the experimental results obtained so far and on what, from these results, can be inferred about the sources of UHECRs.

Very high energy particles interact with Earth’s atmosphere (28 radiation length of thickness) producing the so-called extensive air showers. Energetic particles in the showers generate Cherenkov radiation, which can be collected by an optical reflector and focused on a camera of photo-multipliers. In such a way the atmosphere and the telescope (reflector + camera) work as an imaging calorimeter.