296 research outputs found
Full Geant4 and FLUKA simulations of an e-LINAC for its use in particle detectors performance tests
No full textIn this work we present the results of full Geant4 and FLUKA simulations and comparison with dosimetry data of an electron LINAC of St. Maria Hospital located in Terni, Italy. The facility is being used primarily for radiotherapy and the goal of the present study is the detailed investigation of electron beam parameters to evaluate the possibility to use the e-LINAC (during time slots when it is not used for radiotherapy) to test the performance of detector systems, in particular those designed to operate in space. The critical beam parameters are electron energy, profile and flux available at the surface of device to be tested. The present work aims to extract these parameters from dosimetry calibration data available at the e-LINAC. The electron energy ranges from 4 MeV to 20 MeV. The dose measurements have been performed by using an Advanced Markus Chamber which has a small sensitive volume
A combined approach to the simulation of ionizing radiation effects in silicon devices
No full textSilicon devices (both pixels and microstrips) have been widely used in the past years in High Energy Physics experiments and also in other applications involving the detection of ionizing radiation such as medical imaging and dosimetry. The simulation of the silicon devices response to ionizing radiation is an important step needed to understand the performances in terms of signal, noise, spatial and energy resolution as a function of several technology parameters like doping profile, geometrical dimensions, bias voltage. These simulations are routinely carried out using two separate approaches (and tools): radiation interaction with a geometrically segmented silicon material (GEANT4, FLUKA, PENELOPE) taking into account the physical processes and giving as output the deposited energy; transport of generated electron/hole pairs through the device with electronic signal formation (SENTAURUS-TCAD). In this work we propose a new combined approach using both methods, applied to the case of CMOS pixel sensor, to obtain a better understanding of the behavior of the devices
A STUDY OF COSMIC RAY SECONDARIES INDUCED BY THE MIR SPACE STATION USING AMS-01
No full text(AMS-01 COLLABORATION
Development of biosorption-based algal biosensor for Cu(II) using Tetraselmis chuii
No full textA new biosorption-based biosensor using Tetraselmis chuii microalgae was developed for the voltammetric measurement of copper(II). Biosensor was prepared by incorporating non-living biomass in carbon paste. T. chuii incorporated in carbon paste electrodes (CPE) in weight percentages ranging from 2.5 to 20 accumulate copper(II) from solution through passive adsorption. Copper(II) was accumulated, at open circuit, on the algal biosensor and the voltammetric measurements were carried out by differential pulse cathodic stripping voltammetry. The biosensor performance was optimized with respect to the operating conditions. Under the optimal conditions, a detection limit of 4.6 × 10-10 M was obtained with a good precision (R.S.D. = 3.4%, n = 6). The cathodic peak current was linear with concentration in the range of 5.0 × 10-8-1.0 × 10-6 M (r = 0.9981). The developed biosensor was also applied for the determination of copper(II) in real sample. Such an excellent performance of the algal biosensor toward copper(II), represents a very good alternative for developing other sensors. © 2007 Elsevier B.V. All rights reserved
Testing of substrates for flexible optical solar reflectors: Irradiations of nano-hybrid coatings of polyimide films with 20 keV electrons and with 200-400 nm ultraviolet radiation
No full textIn the frame of a project aimed at developing a new type of optical solar reflectors we present the scientific and technological issues addressed during irradiations of nano-hybrid coatings on polyimide films by using 20 keV electron beam from a modified use of Scanning Electron Microscope (SEM) and with ultraviolet (UV) dose equal to 300 space-equivalent Sun hours. Details of a new approach to use SEM for low energy electron irradiations and of a new UV irradiation setup are given
AMS (Alpha Magnetic Spectrometer) experiment for antimatter, dark matter search on international space station alpha
No full textLeptons with E>200 MeV trapped in the Earth's radiation belts
No full textFor the first time, accurate measurements of electron and positron fluxes in the energy range 0.2–10 GeV have been performed with the Alpha Magnetic Spectrometer (AMS) at altitudes of 370–390 km in the geographic latitude interval ±51.7°. We describe the observed under-cutoff lepton fluxes outside the region of the South Atlantic Anomaly. The separation in quasi-trapped, long-lifetime (O(10 s)), and albedo, short-lifetime (O(100 ms)), components is explained in terms of the drift shell populations observed by AMS. A significantly higher relative abundance of positrons with respect to electrons is seen in the quasi-trapped population. The flux maps as a function of the canonical adiabatic variables L, α0 are presented for the interval 0.95 < L < 3, 0° < α0 < 90° for electrons (E < 10 GeV) and positrons (E < 3 GeV). The results are compared to existing data at lower energies. The properties of the observed under-cutoff particles are also investigated in terms of their residence times and geographical origin
AMS (Alpha Magnetic Spectrometer) experiment for antimatter, dark matter search on International Space Station Alpha
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