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Search Results: 1 - 10 of 401374 matches for " M. Zavatarelli "
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The Adriatic Sea modelling system: a nested approach
M. Zavatarelli,N. Pinardi
Annales Geophysicae (ANGEO) , 2003,
Abstract: A modelling system for the Adriatic Sea has been built within the framework of the Mediterranean Forecasting System Pilot Project. The modelling system consists of a hierarchy of three numerical models (whole Mediterranean Sea, whole Adriatic Sea, Northern Adriatic Basin) coupled among each other by simple one-way, off-line nesting techniques, to downscale the larger scale flow field to highly resolved coastal scale fields. Numerical simulations have been carried out under climatological surface forcing. Simulations were aimed to assess the effectiveness of the nesting techniques and the skill of the system to reproduce known features of the Adriatic Sea circulation phenomenology (main circulation features, dense water formation,flow at the Otranto Strait and coastal circulation characteristics over the northern Adriatic shelf), in view of the pre-operational use of the modelling system. This paper describes the modelling system setup, and discusses the simulation results for the whole Adriatic Sea and its northern basin, comparing the simulations with the observed climatological circulation characteristics. Results obtained with the northern Adriatic model are also compared with the corresponding simulations obtained with the coarser resolution Adriatic model. Key words. Oceanography: general (continental shelf processes; numerical modelling) – Oceanography: physical (general circulation)
Calibration and validation of a one-dimensional complex marine biogeochemical flux model in different areas of the northern Adriatic shelf
M. Vichi,P. Oddo,M. Zavatarelli,A. Coluccelli
Annales Geophysicae (ANGEO) , 2003,
Abstract: In this paper we show results from numerical simulations carried out with a complex biogeochemical fluxes model coupled with a one-dimensional high-resolution hydrodynamical model and implemented at three different locations of the northern Adriatic shelf. One location is directly affected by the Po River influence, one has more open-sea characteristics and one is located in the Gulf of Trieste with an intermediate behavior; emphasis is put on the comparison with observations and on the functioning of the northern Adriatic ecosystem in the three areas. The work has been performed in a climatological context and has to be considered as preliminary to the development of three-dimensional numerical simulations. Biogeochemical model parameterizations have been ameliorated with a detailed description of bacterial substrate utilization associated with the quality of the dissolved organic matter (DOM), in order to improve the models capability in capturing the observed DOM dynamics in the basin. The coupled model has been calibrated and validated at the three locations by means of climatological data sets. Results show satisfactory model behavior in simulating local seasonal dynamics in the limit of the available boundary conditions and the one-dimensional implementation. Comparisons with available measurements of primary and bacterial production and bacterial abundances have been performed in all locations. Model simulated rates and bacterial dynamics are in the same order of magnitude of observations and show a qualitatively correct time evolution. The importance of temperature as a factor controlling bacteria efficiency is investigated with sensitivity experiments on the model parameterizations. The different model behavior and pelagic ecosystem structure developed by the model at the three locations can be attributed to the local hydrodynamical features and interactions with external inputs of nutrients. The onset of the winter/spring bloom in the climatological simulations is primarily driven by local stratification conditions. During summer the major carbon-transfer pathway developed by the model is the microbial web at all the sites, indicating that a large fraction of organic matter is processed through bacteria during productive periods, as suggested by field observations. The site directly influenced by riverine inputs differs from the others, showing a more alternate shifting among trophic pathways. Applying the conceptual scheme proposed by Legendre and Rassoulzadegan (Ophelia, 41, 153-172, 1995), it can be recognized as a herbivorous spring phase
Reactor Antineutrinos Signal all over the world
B. Ricci,F. Mantovani,M. Baldoncini,J. Esposito,L. Ludhova,S. Zavatarelli
Physics , 2014,
Abstract: We present an updated estimate of reactor antineutrino signal all over the world, with particular attention to the sites proposed for existing and future geo-neutrino experiment. In our calculation we take into account the most updated data on Thermal Power for each nuclear plant, on reactor antineutrino spectra and on three neutrino oscillation mechanism.
Studying the Earth with Geoneutrinos
L. Ludhova,S. Zavatarelli
Advances in High Energy Physics , 2013, DOI: 10.1155/2013/425693
Abstract: Geoneutrinos, 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 interdisciplinary field of neutrino geoscience. We give here a broad geological introduction highlighting the points where the geoneutrino 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 Earth's radiogenic heat power. The perspectives and the future projects having geo-neutrinos among their scientific goals are also discussed. 1. Introduction The newly born interdisciplinar field of neutrino geoscience takes the advantage of the technologies developed by large-volume neutrino experiments and of the achievements of the elementary particle physics in order to study the Earth interior with new probe geoneutrinos. Geoneutrinos are electron antineutrinos released in the decays of radioactive elements with lifetimes comparable with the age of the Earth and distributed through the Earth’s interior. The radiogenic heat released during the decays of these Heat Producing Elements (HPE) is in a well fixed ratio with the total mass of HPE inside the Earth. Geoneutrinos bring to the Earth’s surface an instant information about the distribution of HPE. Thus, it is, in principle, possible to extract from measured geoneutrino fluxes several geological information completely unreachable by other means. This information concerns the total abundance and distribution of the HPE inside the Earth and thus the determination of the fraction of radiogenic heat contribute to the total surface heat flux. Such a knowledge is of critical importance for understanding complex processes such as the mantle convection, the plate tectonics, and the geodynamo (the process of generation of the Earth’s magnetic field), as well as the Earth formation itself. Currently, only two large-volume, liquid-scintillator neutrino experiments, KamLAND in Japan and Borexino in Italy, have been able to measure the geoneutrino signal. Antineutrinos can interact only through the weak interactions. Thus, the cross-section of the inverse-beta decay detection interaction: is very low. Even a typical flux of the order of geoneutrinos ? leads to only a hand-full number of
The Adriatic basin forecasting system
Acta Adriatica , 2006,
Abstract: A regional ocean forecasting system has been implemented in the framework of the ADRIatic sea integrated COastal areaS and river basin Management system Pilot Project (ADRICOSM). The system is composed of a 5 km horizontal resolution model and an observing system collecting coastal and open ocean hydrological data. The numerical model is based on the Princeton Ocean Model using a SMOLARKIEWICZ iterative advection scheme, interactive air-sea flux computation, Po and other Adriatic rivers flow rates and is one-way nested to a general circulation model of the Mediterranean Sea. In this study the data from the observing system are used only for model validation. The results of the first operational year are shown and the model performance has been assessed based on root mean square (RMS) criteria.
First Measurement of the He3+He3-->He4+2p Cross Section down to the Lower Edge of the Solar Gamow Peak
The LUNA Collaboration,R. Bonetti,C. Broggini,L. Campajola,P. Corvisiero,A. D'Alessandro,M. Dessalvi,A. D'Onofrio,A. Fubini,G. Gervino,L. Gialanella,U. Greife,A. Guglielmetti,C. Gustavino,G. Imbriani,M. Junker,P. Prati,V. Roca,C. Rolfs,M. Romano,F. Schuemann,F. Strieder,F. Terrasi,H. P. Trautvetter,S. Zavatarelli
Physics , 1999, DOI: 10.1103/PhysRevLett.82.5205
Abstract: We give the LUNA results on the cross section measurement of a key reaction of the proton-proton chain strongly affecting the calculated neutrino luminosity from the Sun: He3+He3-->He4+2p. Due to the cosmic ray suppression provided by the Gran Sasso underground laboratory it has been possible to measure the cross section down to the lower edge of the solar Gamow peak, i.e. as low as 16.5 keV centre of mass energy. The data clearly show the cross section increase due to the electron screening effect but they do not exhibit any evidence for a narrow resonance suggested to explain the observed solar neutrino flux.
Solar neutrino detection in a large volume double-phase liquid argon experiment
D. Franco,C. Giganti,P. Agnes,L. Agostino,B. Bottino,S. Davini,S. De Cecco,A. Fan,G. Fiorillo,C. Galbiati,A. M. Goretti,E. V. Hungerford,Al. Ianni,An. Ianni,C. Jollet,L. Marini,C. J. Martoff,A. Meregaglia,L. Pagani,M. Pallavicini,E. Pantic,A. Pocar,A. L. Renshaw,B. Rossi,N. Rossi,Y. Suvorov,G. Testera,A. Tonazzo,H. Wang,S. Zavatarelli
Physics , 2015,
Abstract: The direct search for dark matter WIMP particles through their interaction with nuclei at the "neutrino floor" sensitivity, where neutrino-induced coherent scattering on nuclei starts contributing to the background, requires detectors capable of collecting exposures of the order of 1~ktonne yr free of background resulting from beta and gamma decays and cosmogenic and radiogenic neutrons. The same constraints are required for precision measurements of solar neutrinos elastically scattering on electrons. Two-phase liquid argon time projection chambers (LAr TPCs) are prime candidates for the ambitious program to explore the nature of dark matter. The large target, high scintillation light yield and good spatial resolution in all three cartesian directions concurrently allows a high precision measurement of solar neutrino fluxes. We studied the cosmogenic and radiogenic backgrounds affecting solar neutrino detection in a 300 tonne (100 tonne fiducial) LAr TPC operating at LNGS depth (3,800 meters of water equivalent). Such a detector could measure the CNO neutrino rate with 5 sigma sensitivity, and significantly improve the precision of the 7Be and pep neutrino rates compared to the currently available results from the Borexino organic liquid scintillator detector. Measurements with ~2%, ~10% and ~15% precision for 7Be, pep, and CNO neutrinos, respectively, are possible.
The Cross Section of 3He(3He,2p)4He measured at Solar Energies
The LUNA Collaboration,M. Junker,A. D'Alessandro,S. Zavatarelli,C. Arpesella,E. Bellotti,C. Broggini,P. Corvisiero,G. Fiorentini,A. Fubini,G. Gervino,U. Greife,C. Gustavino,J. Lambert,P. Prati,W. S. Rodney,C. Rolfs,F. Strieder,H. P. Trautvetter,D. Zahnow
Physics , 1997, DOI: 10.1103/PhysRevC.57.2700
Abstract: We report on the results of the \hethet\ experiment at the underground accelerator facility LUNA (Gran Sasso). For the first time the lowest projectile energies utilized for the cross section measurement correspond to energies below the center of the solar Gamow peak ($E_{\rm 0}$=22 keV). The data provide no evidence for the existence of a hypothetical resonance in the energy range investigated. Although no extrapolation is needed anymore (except for energies at the low-energy tail of the Gamow peak), the data must be corrected for the effects of electron screening, clearly observed the first time for the \hethet\ reaction. The effects are however larger than expected and not understood, leading presently to the largest uncertainty on the quoted $S_{\rm b}(E_{\rm 0})$ value for bare nuclides (=5.40 MeV b).
Formation Of A Cold Antihydrogen Beam in AEGIS For Gravity Measurements
G. Testera,A. S. Belov,G. Bonomi,I. Boscolo,N. Brambilla,R. S. Brusa,V. M. Byakov,L. Cabaret,C. Canali,C. Carraro,F. Castelli,S. Cialdi,M. de Combarieu,D. Comparat,G. Consolati,N. Djourelov,M. Doser,G. Drobychev,A. Dupasquier,D. Fabris,R. Ferragut,G. Ferrari,A. Fischer,A. Fontana,P. Forget,L. Formaro,M. Lunardon,A. Gervasini,M. G. Giammarchi,S. N. Gninenko,G. Gribakin,R. Heyne,S. D. Hogan,A. Kellerbauer,D. Krasnicky,V. Lagomarsino,G. Manuzio,S. Mariazzi,V. A. Matveev,F. Merkt,S. Moretto,C. Morhard,G. Nebbia,P. Nedelec,M. K. Oberthaler,P. Pari,V. Petracek,M. Prevedelli,I. Y. Al-Qaradawi,F. Quasso,O. Rohne,S. Pesente,A. Rotondi,S. Stapnes,D. Sillou,S. V. Stepanov,H. H. Stroke,G. Tino,A. Vairo,G. Viesti,H. Walters,U. Warring,S. Zavatarelli,A. Zenoni,D. S. Zvezhinskij,for the AEGIS Proto-Collaboration
Physics , 2008, DOI: 10.1063/1.2977857
Abstract: The formation of the antihydrogen beam in the AEGIS experiment through the use of inhomogeneous electric fields is discussed and simulation results including the geometry of the apparatus and realistic hypothesis about the antihydrogen initial conditions are shown. The resulting velocity distribution matches the requirements of the gravity experiment. In particular it is shown that the inhomogeneous electric fields provide radial cooling of the beam during the acceleration.
Prospects for measuring the gravitational free-fall of antihydrogen with emulsion detectors
AEgIS Collaboration,S. Aghion,O. Ahlén,C. Amsler,A. Ariga,T. Ariga,A. S. Belov,G. Bonomi,P. Br?unig,J. Bremer,R. S. Brusa,L. Cabaret,C. Canali,R. Caravita,F. Castelli,G. Cerchiari,S. Cialdi,D. Comparat,G. Consolati,J. H. Derking,S. Di Domizio,L. Di Noto,M. Doser,A. Dudarev,A. Ereditato,R. Ferragut,A. Fontana,P. Genova,M. Giammarchi,A. Gligorova,S. N. Gninenko,S. Haider,J. Harasimovicz,S. D. Hogan,T. Huse,E. Jordan,L. V. J?rgensen,T. Kaltenbacher,J. Kawada,A. Kellerbauer,M. Kimura,A. Knecht,D. Krasnicky,V. Lagomarsino,A. Magnani,S. Mariazzi,V. A. Matveev,F. Moia,G. Nebbia,P. Nédélec,M. K. Oberthaler,N. Pacifico,V. Petrácek,C. Pistillo,F. Prelz,M. Prevedelli,C. Regenfus,C. Riccardi,O. R?hne,A. Rotondi,H. Sandaker,P. Scampoli,A. Sosa,J. Storey,M. A. Subieta Vasquez,M. Spacek,G. Testera,D. Trezzi,R. Vaccarone,C. P. Welsch,S. Zavatarelli
Physics , 2013, DOI: 10.1088/1748-0221/8/08/P08013
Abstract: The main goal of the AEgIS experiment at CERN is to test the weak equivalence principle for antimatter. AEgIS will measure the free-fall of an antihydrogen beam traversing a moir\'e deflectometer. The goal is to determine the gravitational acceleration g for antihydrogen with an initial relative accuracy of 1% by using an emulsion detector combined with a silicon micro-strip detector to measure the time of flight. Nuclear emulsions can measure the annihilation vertex of antihydrogen atoms with a precision of about 1 - 2 microns r.m.s. We present here results for emulsion detectors operated in vacuum using low energy antiprotons from the CERN antiproton decelerator. We compare with Monte Carlo simulations, and discuss the impact on the AEgIS project.
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