1,691 research outputs found
Optical Polarimetry for Fundamental Physics
No full textSensitive magneto-optical polarimetry was proposed by E. Iacopini and E. Zavattini in 1979 to detect vacuum electrodynamic non-linearity, in particular Vacuum Magnetic Birefringence (VMB). This process is predicted in QED via the fluctuation of electron–positron virtual pairs but can also be due to hypothetical Axion-Like Particles (ALPs) and/or MilliCharged Particles (MCP). Today ALPs are considered a strong candidate for Dark Matter. Starting in 1992 the PVLAS collaboration, financed by INFN, Italy, attempted to measure VMB conceptually following the original 1979 scheme based on an optical cavity permeated by a time-dependent magnetic field and heterodyne detection. Two setups followed differing basically in the magnet: the first using a rotating superconducting 5.5 T dipole magnet at the Laboratori Nazionali di Legnaro, Legnaro, Italy and the second using two rotating permanent 2.5 T dipole magnets at the INFN section of Ferrara. At present PVLAS is the experiment which has set the best limit in VMB reaching a noise floor within a factor 7 of the predicted QED signal: Δn(QED)=2.5×10−23 @ 2.5 T. It was also shown that the noise floor was due to the optical cavity and a larger magnet is the only solution to increase the signal to noise ratio. The PVLAS experiment ended at the end of 2018. A new effort, VMB@CERN, which plans to use a spare LHC dipole magnet at CERN with a new modified optical scheme, is now being proposed. In this review, a detailed description of the PVLAS effort and the comprehension of its limits leading to a new proposal will be given
PRIN 2009 - Ellissometria ottica per esperimenti di fisica fondamentale
No full textIl progetto si inquadra nel problema delle verifiche sperimentali dell'Elettrodinamica
Quantistica (QED) e più in generale delle proprietà del vuoto quantistico strutturato; in
particolare si intendono studiare gli effetti non lineari che si manifestano nella propagazione
della luce in vuoto in presenza di campi elettrici e/o magnetici
Probing for new physics and detecting non-linear vacuum QED effects using gravitational wave interferometer antennas
No full textNew Physics with GW antenna used for QED vacuum probin
Advances in SPECT Instrumentation (including Small Animal Scanners)
No full textFundamental major efforts have been devoted to the development of
positron emission tomography (PET) imaging modality over the last few decades. Recently, a novel surge of interest in single photon emission computed tomography (SPECT) technology has occurred,
particularly after the introduction of the hybrid SPECT-CT imaging
system. This has led to a flourishing of investigations in new types of detectors and collimators, and to more accurate refinement of reconstruction algorithms. Along with SPECT-CT, new, fast gamma cameras have been developed for dedicated cardiac imaging. The existing gap between PET and SPECT in sensitivity and spatial resolution is progressively decreasing, and this trend is particularly
apparent in the field of small animal imaging where the most important advances have been reported in SPECT tomographs. An outline of the basic features of SPECT technology, and of
recent developments in SPECT instrumentation for both clinical applications and basic biological research on animal models is described
Chapter 10: Small Animal Scanners
No full text"Ionizing Radiation Detectors for Medical Imaging" contains ten technical chapters, half of which are devoted to radiology and the other half to nuclear medicine. The last chapter describes the detectors for radiotherapy and portal imaging. Each chapter addresses completely a specific application. The emphasis is always on detector fundamentals and detector properties. Where necessary, software and specific applications are described in depth. The book is intended for graduate and undergraduate students in physics and engineering who want to study medical imaging. In addition, scientists who are working in a specific sub-field of medical imaging can acquire from the book an up-to-date description of the state of the art in related sub-fields, within the scope of ionizing radiation detectors. Other scientists, as well as physicians, can use the book as a reference for medical imaging
Erratum to: A polarisation modulation scheme for measuring vacuum magnetic birefringence with static fields (The European Physical Journal C, (2016), 76, 5, (294), 10.1140/epjc/s10052-016-4139-0)
No full textIn the original article unfortunately we missed two typos in the equation for I(δ) at the top of the fourth page of the article. © 2017, The Author(s)
Quality of life in chronic diseases of the aged: The importance of cognitive deterioration
No full textThe interference of a chronic disease on the aging process reduces patients efficiency in confronting everyday life events and their Quality of Life (QOL). The purpose of this study was to examine the interaction between cognitive problems and emotional difficulties as related to several chronic diseases commonly present among aged patients in contributing to their QOL reduction. Diseases considered were: chronic cerebro-vascular disorders non-insulin dependent diabetes mellitus and hypertension. Memory characteristics and subjective evaluation of several areas of daily living where problems could be present were assessed. Severity of cognitive and behavioral deterioration emerged as a major component independent from type of disease, contributing to reduction of QOL. Disease type determined the different risk of presence of an objective reduction of memory efficiency. The QOL of aged patients was identified as a multidimensional array of different components among which cognitive deterioration assumes a primary role. These results, together with analogous findings from previous studies, underline the importance of considering cognitive efficiency in aged patients even with chronic diseases not directly affecting CNS in order to evaluate their needs
"La materia quando inizia a soffrire": Denial Figures in Guido Morselli's Work
No full textopenIl presente lavoro si propone di indagare la questione della crisi del soggetto così come discussa dall'autore italiano Guido Morselli, nelle diverse sedi dei romanzi, della produzione saggistica e del diario personale. Da qui si analizzeranno temi quali il solipsismo e gli interrogativi esistenziali, fin dai loro primi riverberi nella filosofia centro-europea di fine Ottocento, inizio Novecento.The present work aims yo investigate the issue of the crisis of the subject, as it is discussed by the Italian author Guido Morselli, on his novels, essays and personal diary. We will also analyze topics such as solipsism and existential questions from their first reverberations on the late eighteen century and early nineteen century middle European philosophy
Discovery of an X-ray afterglow associated with the gamma-ray burst of 28 February 1997
No full textEstablishing the nature of γ-ray bursts is one of the greatest challenges in high-energy astrophysics. The distribution of these bursts is isotropic across the sky, but inhomogeneous in space, with a deficit of faint bursts. It is currently unknown whether γ-ray bursts are produced in our Galaxy or at cosmological distances. The detection and identification of counterparts at other wavelengths are seen as crucial for resolving the origin of the events. Here we report the detection by the Beppo-SAX satellite of an X-ray 'afterglow', associated with the γ-ray burst of 28 February 1997 (GRB970228; ref. 3) - the first such detection for any γ-ray burst. The X- ray transient was found to contain a significant fraction of the total energy of the γ-ray burst and, following the initial detection eight hours after the main burst, faded within a few days with a power-law decay function. The rapid locating of this γ-ray burst instigated a multi-wavelength observational campaign that culminated in the identification of a fading optical transient in a position consistent with the X-ray transient reported here
YAP-PET: first results of a small animal Positron Emission Tomograph based on YAP:Ce finger crystals
No full textWe have built a small animal Positron Emission Tomograph (YAP-PET) based on four matrices of 400 YAP:Ce finger crystals (2x2~30 mm3 each) coupled to Position Sensitive PhotoMultiplier Hamamatsu R2486-06. The system consists of four detectors on a rotating gantry with a variable diameter from 10 and 25 cm. The read-out and data acquisition system are handled by NIM-CAMAC standard electronics. The tomograph has a total Field Of View (FOV) of 4 x 4 ~ 4cm 3 that is appropriate for mice and rat studies. A spatial resolution I 2 mm over 3 x 3 ~ 3c m3 FOV has been measured, with a peak sensitivity for a point source of about 614 cpslyci for a gantry diameter of 15 cm and an energy threshold of 50 keV
- …
