A radiation probe was designed for indirectly determining the high voltage of a Mo anode mammography unit. The real time processing of the probe outputs yields exposure time, voltage waveform, kVp, ...and ripple in the range 24-40 kVp useful for screen-film mammography. The probe, connected to a portable computer, will be employed in a survey of radiation dose and image quality in mammography as part of an ongoing program in Italy.
The evolution of telecommunication systems is shifting towards the higher portion of the microwave spectrum to achieve higher data rate as well as to non-geosynchronous orbit (non-GSO) satellites. ...The use of frequency at Ka band and above can be very challenging due to the non-negligible effects of the atmosphere, but also the exploitation of medium-Earth orbit (MEO) and low-Earth-orbit (LEO) satellite needs to tackle the dynamical angular behavior of the channel itself. This paper describes the architecture and preliminary measurements of the Italian receivers for the ESA-funded MEKaP (MEO Ka-band Propagation) experimentation. The activity involves several partners, such as Politecnico di Milano, Sapienza Università di Roma, Instituto de Telecomunicações-Aveiro Pole, and Thales Alenia Space - Italia. A total of four receivers (three in Italy and one in Portugal) will create a network of Ka-band shared data with the main objectives of characterizing the MEO-satellite tropospheric propagation impairments for co-polarized as well as cross-polarized channels. We describe the detailed architecture of the MeKaP twin receiving stations in Rome and Milan, sharing the same design, and on the preliminary measurements acquired and post-processed thanks to the overall effort of the MaKaP international research group.
The modeling of the earth-satellite propagation channel requires experimental data that is usually obtained by monitoring continuous wave (CW) signal sources installed in satellites (beacons). ...Although there is considerable experience in the development of beacon receivers for geostationary satellites, this is not the case for Medium Earth Orbit (MEO) or Low Earth Orbit (LEO) constellations. The main considerations for the development of propagation receivers for monitoring MEO satellites are addressed in this article. The target constellation is presented with a description of the satellite orbits, characteristics of the beacon payload and the project requirements. The receiver's requirements are then analyzed, starting with the antenna, satellite tracking, beacon detection and propagation data handling.
The AlphaSat TDP5 experiment, also now as Aldo Paraboni, is a scientific experiment held by the European Space Agency (ESA) to investigate radio propagation channel in the Ka and Q bands. The ...AlphaSat satellite was launched in orbit in 2013 and since then several European research group have been monitoring the received beacon signals to model physical effects of the atmosphere on the transmitted electromagnetic field. This article is aimed to describe the AlphaSat receiving station in Rome, focusing on the latest upgrade of the Ka-band receiver. Focused attention will be payed to the new tracking system for the Ka-band receiver and related enhancements of the overall performance. At the end, a case study from the acquired data-set will be analyzed aiming at the effects on the signal due to the atmospheric turbulence and rain.
The Alphasat Aldo Paraboni Experiment is a radio propagation experiment in the Ka and Q bands started in 2013 with the launch of the Alphasat satellite. It consists of two CW beacons transmitted from ...the satellite to a large area centered on Europe. Sapienza University, in cooperation with Istituto Superiore delle Comunicazioni (ISCOM) and Fondazione Ugo Bordoni (FUB), joined this experimentation from the very beginning with the installation of two receivers, one for each band. In this article we will show the last technology upgrades made on the Q-band receiver of the Rome AlphaSat receiving station. Particular attention will be put on the custom tracking system based on ephemeris, its realization, specification and performance. A comparison between measured data before and after the installation will be given. At the end we will analyse clear air scintillation data acquired by the upgraded station to prove the quality of the whole system.
Scintillations affect the propagated signal with an unwanted aleatory oscillation at the receiver. A first analysis of data acquired from Alphasat Q-band receiver station, located in Spino d'Adda ...(Italy), is performed. Correlation between meteorological measurements at the ground and measured scintillation from the Q-band beacon receiver (i.e., fluctuation of the received electromagnetic field) is investigated. Radiosounding data from north Italy station of "Milano Linate" have been collected for the entire year 2015 and used to calculate the refractive index structure constant. Subsequently the amplitude scintillation variance is derived through the use of the Rytov model on the slant path. Results obtained using the scintillation model are compared with measured data from Alphasat beacon receiver, investigating the statistical correlation in clear air condition between simulated and measured data.
The machine described in this document is an advanced Source of up to 20 MeV Gamma Rays based on Compton back-scattering, i.e. collision of an intense high power laser beam and a high brightness ...electron beam with maximum kinetic energy of about 720 MeV. Fully equipped with collimation and characterization systems, in order to generate, form and fully measure the physical characteristics of the produced Gamma Ray beam. The quality, i.e. phase space density, of the two colliding beams will be such that the emitted Gamma ray beam is characterized by energy tunability, spectral density, bandwidth, polarization, divergence and brilliance compatible with the requested performances of the ELI-NP user facility, to be built in Romania as the Nuclear Physics oriented Pillar of the European Extreme Light Infrastructure. This document illustrates the Technical Design finally produced by the EuroGammaS Collaboration, after a thorough investigation of the machine expected performances within the constraints imposed by the ELI-NP tender for the Gamma Beam System (ELI-NP-GBS), in terms of available budget, deadlines for machine completion and performance achievement, compatibility with lay-out and characteristics of the planned civil engineering.
The authors have developed a TDC+Transputer-based acquisition system to study the X-ray imaging capabilities of a silicon /spl mu/-strip detector with 100 and 200 /spl mu/m read-out pitch. This ...system allows real-time image acquisition and display. The authors present images obtained with an X-ray mammography tube using sub-millimeter high contrast test objects on a 16*16 channels prototype.< >
The aim of the optimization program for mammography (DQM) in Italy is to achieve the best compromise between image quality and dose to patient. 272 centers agreed to the second phase of the program, ...from February 1987 to January 1990. Exposure, half-value layer (HVL) and focal spot size were measured according to the same methods employed in the first phase of the DQM program (1985), while image quality was evaluated by means of a new performance phantom. The average exposure was 0.96 R (2.48 x 10(-4) C/kg); in 173 (64.3%) centers exposure was less than 1 R (2.58 x 10(-4) C/kg), and only in 3 centers, where a direct X-ray film was employed, was exposure greater than 5 R (12.9 x 10(-4) C/kg). In every center the average whole-breast dose to a reference organ (5 cm thick, composed of 50% fat + 50% water) was calculated on the basis of entrance exposure, HVL, and focus-skin distance; in 63.2% of the centers doses less than 0.15 cGy were employed. The results allowed dose and image quality to be correlated in order to divide the centers (using a film-screen system) into groups with a different efficiency level: in 101 centers dose and image quality were good, in 64 centers too high a dose was employed, in 66 centers image quality was poor, and in 38 centers dose was too high and image quality was poor. It must be stressed that the DQM program can play its role only if each center carries out its Quality Assurance activity after the methods recommended by the World Health Organization.
