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Search Results: 1 - 10 of 208536 matches for " L. Ludhova "
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Review article "Geo-neutrinos"
L. Ludhova
Geoscientific Instrumentation, Methods and Data Systems (GI) & Discussions (GID) , 2012, DOI: 10.5194/gi-1-221-2012
Abstract: Geo-neutrinos, electron anti-neutrinos produced in β-decays of naturally occurring radioactive isotopes in the Earth, are a unique direct probe of our planet's interior. After a brief introduction about the Earth (mostly for physicists) and the very basics about the neutrinos and anti-neutrinos (mostly for geologists), I describe the geo-neutrino properties and the main aims of their study. An overview of the latest experimental results obtained by KamLAND and Borexino experiments is provided. A short overview of future perspectives of this new inter-disciplinary field is given.
Geo-neutrinos
L. Ludhova
Geoscientific Instrumentation, Methods and Data Systems Discussions , 2012, DOI: 10.5194/gid-2-539-2012
Abstract: Geo-neutrinos, electron anti-neutrinos produced in β-decays of naturally occurring radioactive isotopes in the Earth, are a unique direct probe of our planet's interior. After a brief introduction about the Earth (mostly for physicists) and the very basics about the neutrinos and anti-neutrinos (mostly for geologists), I describe the geo-neutrinos' properties and the main aims of their study. An overview of the latest experimental results obtained by KamLand and Borexino experiments is provided. A short overview of future perspectives of this new inter-disciplinary field is given.
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
Oscillations at low energies
D. A. Dwyer,L. Ludhova
Physics , 2015,
Abstract: A concise summary of the "Oscillation at low energies" parallel session at the 2014 Neutrino Oscillation Workshop is provided. Plans to use man-made neutrinos and antineutrinos to determine the neutrino mass hierarchy, search for sterile neutrinos, and to observe coherent neutrino-nucleus scattering were discussed. Potential measurements of solar neutrinos, supernova neutrinos, and geoneutrinos are also summarized.
Neutrino Oscillations
G. Bellini,L. Ludhova,G. Ranucci,F. L. Villante
Advances in High Energy Physics , 2014, DOI: 10.1155/2014/191960
Abstract: In the last decades, a very important breakthrough has been brought about in the elementary particle physics by the discovery of the phenomenon of the neutrino oscillations, which has shown neutrino properties beyond the Standard Model. But a full understanding of the various aspects of the neutrino oscillations is far to be achieved. In this paper the theoretical background of the neutrino oscillation phenomenon is described, referring in particular to the paradigmatic models. Then the various techniques and detectors which studied neutrinos from different sources are discussed, starting from the pioneering ones up to the detectors still in operation and to those in preparation. The physics results are finally presented adopting the same research path which has been crossed by this long saga. The problems not yet fixed in this field are discussed, together with the perspectives of their solutions in the near future. 1. Introduction Neutrino studies brought us to some of the most relevant breakthroughs in particle physics of last decades. In spite of that, the neutrino properties are still far to be completely understood. The discovery of the oscillation phenomenon produced quite a revolution in the Standard Model of elementary particles, especially through the direct evidence of a nonzero neutrino mass. The first idea of neutrino oscillations was considered by Pontecorvo in 1957 [1–3], before any experimental indication of this phenomenon. After several-decades-lasting saga of experimental and theoretical research, many questions are still open around the interpretation of this phenomenon and on the correlated aspects, on the oscillation parameters, on the neutrino masses, on the mass hierarchy, on CP violation in the leptonic sector, and on a possible existence of a fourth, sterile neutrino. The generally accepted MSW model [4–6] to interpret solar neutrino oscillations is presently validated for the oscillation in vacuum and in matter, but not yet in the vacuum-matter transition region. The shape of this transition could be influenced in a relevant way, as suggested by various theories going beyond the Standard Model as, for example, the nonstandard neutrino interactions and a possible existence of a very light sterile neutrino. For this reason, the transition region deserves further and refined experimental studies. Checks on the neutrino oscillations are under way through several experiments in data-taking phase, while few others are in preparation or even construction. These projects exploit various approaches, for example, neutrino-flavor
Geo-neutrinos
G. Bellini,A. Ianni,L. Ludhova,F. Mantovani,W. F. McDonough
Physics , 2013, DOI: 10.1016/j.ppnp.2013.07.001
Abstract: We review a new interdisciplinary field between Geology and Physics: the study of the Earth's geo-neutrino flux. We describe competing models for the composition of the Earth, present geological insights into the make up of the continental and oceanic crust, those parts of the Earth that concentrate Th and U, the heat producing elements, and provide details of the regional settings in the continents and oceans where operating and planned detectors are sited. Details are presented for the only two operating detectors that are capable of measuring the Earth's geo-neutrinos flux: Borexino and KamLAND; results achieved to date are presented, along with their impacts on geophysical and geochemical models of the Earth. Finally, future planned experiments are highlighted.
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.
Characterization of large area avalanche photodiodes in X-ray and VUV-light detection
L. M. P. Fernandes,F. D. Amaro,A. Antognini,J. M. R. Cardoso,C. A. N. Conde,O. Huot,P. E. Knowles,F. Kottmann,J. A. M. Lopes,L. Ludhova,C. M. B. Monteiro,F. Mulhauser,R. Pohl,J. M. F. dos Santos,L. A. Schaller,D. Taqqu,J. F. C. A. Veloso
Physics , 2007, DOI: 10.1088/1748-0221/2/08/P08005
Abstract: The present manuscript summarizes novel studies on the application of large area avalanche photodiodes (LAAPDs) to the detection of X-rays and vacuum ultraviolet (VUV) light. The operational characteristics of four different LAAPDs manufactured by Advanced Photonix Inc., with active areas of 80 and 200 mm^2 were investigated for X-ray detection at room temperature. The best energy resolution was found to be in the 10-18% range for 5.9 keV X-rays. The LAAPD, being compact, simple to operate and with high counting rate capability (up to about 10^5/s), proved to be useful in several applications, such as low-energy X-ray detection, where they can reach better performance than proportional counters. Since X-rays are used as reference in light measurements, the gain non-linearity between 5.9 keV X-rays and light pulses was investigated. The gain ratio between X-rays and VUV light decreases with gain, reaching 10 and 6% variations for VUV light produced in argon (~128 nm) and xenon (~172 nm), respectively, for a gain 200, while for visible light (~635 nm) the variation is lower than 1%. The effect of temperature on the LAAPD performance was investigated. Relative gain variations of about -5% per Celsius degree were observed for the highest gains. The excess noise factor was found to be independent on temperature, being between 1.8 and 2.3 for gains from 50 to 300. The energy resolution is better for decreasing temperatures due mainly to the dark current. LAAPDs were tested under intense magnetic fields up to 5 T, being insensitive when used in X-ray and visible-light detection, while for VUV light a significant amplitude reduction was observed at 5 T.
Muonic hydrogen cascade time and lifetime of the short-lived $2S$ state
L. Ludhova,F. D. Amaro,A. Antognini,F. Biraben,J. M. R. Cardoso,C. A. N. Conde,A. Dax,S. Dhawan,L. M. P. Fernandes,T. W. Haensch,V. W. Hughes,P. Indelicato,L. Julien,P. E. Knowles,F. Kottmann,Y. -W. Liu,J. A. M. Lopes,C. M. B. Monteiro,F. Mulhauser,F. Nez,R. Pohl,P. Rabinowitz,J. M. F. dos Santos,L. A. Schaller,C. Schwob,D. Taqqu,J. F. C. A. Veloso
Physics , 2006, DOI: 10.1103/PhysRevA.75.040501
Abstract: Metastable ${2S}$ muonic-hydrogen atoms undergo collisional ${2S}$-quenching, with rates which depend strongly on whether the $\mu p$ kinetic energy is above or below the ${2S}\to {2P}$ energy threshold. Above threshold, collisional ${2S} \to {2P}$ excitation followed by fast radiative ${2P} \to {1S}$ deexcitation is allowed. The corresponding short-lived $\mu p ({2S})$ component was measured at 0.6 hPa $\mathrm{H}_2$ room temperature gas pressure, with lifetime $\tau_{2S}^\mathrm{short} = 165 ^{+38}_{-29}$ ns (i.e., $\lambda_{2S}^\mathrm{quench} = 7.9 ^{+1.8}_{-1.6} \times 10^{12} \mathrm{s}^{-1}$ at liquid-hydrogen density) and population $\epsilon_{2S}^\mathrm{short} = 1.70^{+0.80}_{-0.56}$ % (per $\mu p$ atom). In addition, a value of the $\mu p$ cascade time, $T_\mathrm{cas}^{\mu p} = (37\pm5)$ ns, was found.
Planar LAAPDs: Temperature Dependence, Performance, and Application in Low Energy X-ray Spectroscopy
L. Ludhova,F. D. Amaro,A. Antognini,F. Biraben,J. M. R. Cardoso,C. A. N. Conde,D. S. Covita,A. Dax,S. Dhawan,L. M. P. Fernandes,T. W. Hansch,V. W. Hughes,O. Huot,P. Indelicato,L. Julien,P. E. Knowles,F. Kottmann,J. A. M. Lopes,Y. -W. Liu,C. M. B. Monteiro,F. Mulhauser,F. Nez,R. Pohl,P. Rabinowitz,J. M. F. dos Santos,L. A. Schaller,D. Taqqu,J. F. C. A. Veloso
Physics , 2004, DOI: 10.1016/j.nima.2004.11.017
Abstract: An experiment measuring the 2S Lamb shift in muonic hydrogen mup is being performed at the Paul Scherrer Institute, Switzerland. It requires small and compact detectors for 1.9 keV x rays (2P-1S transition) with an energy resolution around 25% at 2 keV, a time resolution better than 100 ns, a large solid angle coverage, and insensitivity to a 5 T magnetic field. We have chosen Large Area Avalanche Photodiodes (LAAPDs) from Radiation Monitoring Devices as x-ray detectors, and they were used during the last data taking period in 2003. For x-ray spectroscopy applications, these LAAPDs have to be cooled in order to suppress the dark current noise, hence, a series of tests were performed to choose the optimal operation temperature. Specifically, the temperature dependence of gain, energy resolution, dark current, excess noise factor, and detector response linearity was studied. Finally, details of the LAAPDs application in the muonic hydrogen experiment as well as their response to alpha particles are presented.
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