No Arabic abstract
Geo-neutrinos, electron antineutrinos from natural radioactive decays inside the Earth, bring to the surface unique information about our planet. The new techniques in neutrino detection opened a door into a completely new inter-disciplinary field of Neutrino Geoscience. We give here a broad geological introduction highlighting the points where the geo-neutrino measurements can give substantial new insights. The status-of-art of this field is overviewed, including a description of the latest experimental results from KamLAND and Borexino experiments and their first geological implications. We performed a new combined Borexino and KamLAND analysis in terms of the extraction of the mantle geo-neutrino signal and the limits on the Earths radiogenic heat power. The perspectives and the future projects having geo-neutrinos among their scientific goals are also discussed.
In the present paper, we consider the possibility of interaction between geoneutrinos and the geomagnetic field, by adopting an approach based on the Diracs equation with a non-minimal coupling that accounts for the magnetic interaction of the massive neutrinos. In our approach, we see that the magnetic interaction is controlled by a dimensionless parameter, $fsimeq 10^{-1}$, and we estimate the mean value of this interaction to be of the order of $10^{-14} MeV^{2}$.
Geoneutrinos are electron antineutrinos ($bar u_e$) generated by the beta-decays of radionuclides naturally occurring inside the Earth, in particular $^{238}$U, $^{232}$Th, and $^{40}$K. Measurement of these neutrinos provides powerful constraints on the radiogenic heat of the Earth and tests on the Earth models. Since the prediction of $bar u_e$s in geoneutrino flux is subject to neutrino oscillation effects, we performed a calculation including detailed oscillation analysis in the propagation of geoneutrinos and reactor neutrinos generated around the Earth. The expected geoneutrino signal, the reactor neutrino background rates and the systematic error budget are provided for a proposed 3-kiloton neutrino detector at the Jinping underground lab in Sichuan, China. In addition, we evaluated sensitivities for the geoneutrino flux, Th/U ratio and power of a possible fission reactor in the interior of Earth.
This paper describes the Borexino detector and the high-radiopurity studies and tests that are integral part of the Borexino technology and development. The application of Borexino to the detection and studies of geoneutrinos is discussed.
Micrometeoroids (cosmic dust with size between a few $mu$m and $sim$1 mm) dominate the annual extraterrestrial mass flux to the Earth. We investigate the range of physical processes occurring when micrometeoroids traverse the atmosphere. We compute the time (and altitude) dependent mass loss, energy balance, and dynamics to identify which processes determine their survival for a range of entry conditions. We develop a general numerical model for the micrometeoroid-atmosphere interaction. The equations of motion, energy, and mass balance are simultaneously solved for different entry conditions (e.g. initial radii, incident speeds and angles). Several different physical processes are taken into account in the equation of energy and in the mass balance, in order to understand their relative roles and evolution during the micrometeoroid-atmosphere interaction. In particular, to analyze the micrometeoroid thermal history we include in the energy balance: collisions with atmospheric particles, micrometeoroid radiation emission, evaporation, melting, sputtering and kinetic energy of the ablated mass. Low entry velocities and grazing incidence angles favor micrometeoroid survival. Among those that survive, our model distinguishes (1) micrometeoroids who reach the melting temperature and for which melting is the most effective mass loss mechanism, and (2) micrometeoroids for which ablation due to evaporation causes most of the the mass loss. Melting is the most effective cooling mechanism. Sputtering-induced mass loss is negligible.
Geoneutrino is a new channel of information about geochemical composition of the Earth. We alnalysed here the following problem. What statistics do we need to distinguish between predictions of Bulk Silicate Earth model and Hydridic Earth model for Th/U signal ratio? We obtained the simple formula for estimation of error of Th/U signal ratio. Our calculations show that we need more than $22 kt cdot year$ exposition for Gran-Sasso underground laboratory and Sudbury Neutrino Observatory. We need more than $27 kt cdot year$ exposition for Kamioka site in the case of stopping of all Japanese nuclear power plants.