1,721,578 research outputs found
Calorimetric beta spectroscopy
No full textIn the last decade the energy dispersive spectroscopy of nuclear radiation has made impressive progresses by means of small thermal microcalorimeters operating at about 0.1 K. The present status of this technology, which has achieved 2 eV energy resolution, allows to design a true calorimetric experiment for neutrino mass direct determination with sub-eV sensitivity from the β spectrum of187Re and the E.C. spectrum of163Ho. The calorimetric method, often indicated as solution for a model-independent measurement, allows to overcome the final states problem of impulse spectroscopy. A further reduction of the systematic uncertatinties might be achived by comparing the finite neutrino mass effect of the two isotopes. Here, the motivations, the principles of operations, the results from the first pilot measurements and the future perspectives are described. © Società Italiana di Fisica
Flow non-normality-induced transient growth in superposed Newtonian and non-Newtonian fluid layers
Full text linkIn recent years non-normality and transient growths have attracted much interest in fluid mechanics. Here, we investigate these topics with reference to the problem of interfacial instability in superposed Newtonian and non-Newtonian fluid layers. Under the hypothesis of the lubrication theory, we demonstrate the existence of significant transient growths in the parameter space region where the dynamical system is asymptotically stable, and show how they depend on the main physical parameters. In particular, the key role of the density ratio is highlighte
Contributions of low temperature detectors to neutrino physics
No full textWhile the Standard Model of particle physics has been extremely successful in explaining the precision data obtained in particle physics experiments, evidence of physics beyond the Standard Model has been obtained in recent years. In particular, the observed neutrino flavor oscillations imply that neutrinos have mass, and that they mix. New questions are now open for the future: What is the nature of neutrinos and are they Dirac or Majorana particles? What are the values of the absolute neutrino masses and why are they so small? What is the number of neutrinos and are there sterile neutrinos? Do neutrinos have nonstandard interactions? Do cosmological neutrinos exist and are they detectable? Low temperature detectors are being used to make progress in addressing these questions. The technologies employed complement other experimental techniques. The ultimate aim is to unveil the origin of neutrino properties. © 2009 American Institute of Physics
Positron timing and detection in the MEG experiment
No full textHere the high timing resolution positron detector designed to be used in the MEG experiment is described. Several technical challenges have been faced to obtain the unprecedented goal resolution of 100 ps FWHM for positrons to be detected in the MEG experiment. Also an overview on past experiments is proposed. The key role of the MEG experiment in unveiling New Physics phenomena is briefly stressed. © owned by the author
La corrispondenza epistolare di Arcangelo Corelli tra recuperi e nuovi ritrovamenti: una prima indagine paleografica
No full textL'obiettivo del contributo è stato quello di analizzare la corrispondenza epistolare di Arcangelo Corelli mediante un'ottica paleografica e strutturale, che ha consentito di avvalorare o smentire precedenti ipotesi di autografia di alcune lettere, e di individuare anche l'intervento di altre mani nella stesura delle stess
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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