371 research outputs found

    EURADOS Working Group 6, Computational Dosimetry, a history of promoting good practice via intercomparisons and training

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    This paper is the editorial of a special issue of Radiation Measurements on EURADOS intercomparisons in computational dosimetry. The articles in this special issue cover complex problems in terms of geometry, particle types, energy ranges, coupled calculations and also scale, with the possibility of performing Monte Carlo calculations on micro and nano dosimetric scales now feasible. A summary of the exercises is provided in the first article of the Special Issue, which presents the findings and common conclusions from the ten articles reporting the results of the different exercises. One of these issues was the correct assessment of bone marrow dose, which prompted the inclusion of an article in this special issue explaining the ICRP-recommended method for bone marrow dosimetry.Comment: 5 page

    A telescope detection system for direct and high resolution spectrometry of intense neutron fields

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    A high energy- and spatial-resolution telescope detector was designed and constructed for neutron spectrometry of intense neutron fields. The detector is constituted by a plastic scintillator coupled to a monolithic silicon telescope (MST), in turn consisting of a DE and an E stage. The scintillator behaves as an “active” recoil-proton converter, since it measures the deposited energy of the recoil-protons generated across. The MST measures the residual energy of recoil-protons downstream of the converter and also discriminates recoil-protons from photons associated to the neutron field. The lay-out of the scintillator/MST system was optimized through an analytical model for selecting the angular range of the scattered protons. The use of unfolding techniques for reconstructing the neutron energy distribution was thus avoided with reasonable uncertainty (about 1.6% in neutron energy) and efficiency (of the order of 106 counts per unit neutron fluence). A semi-empirical procedure was also developed for correcting the non-linearity in light emission from the organic scintillator. The spectrometer was characterized with quasi-monoenergetic and continuous fields of neutrons generated at the CN Van De Graaff accelerator of the INFN-Legnaro National Laboratory, Italy, showing satisfactory agreement with literature data

    First results from an aging test of a prototype RPC for the LHCb Muon System

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    Recent results of an aging test performed at the CERN Gamma Irradiation Facility on a single--gap RPC prototype developed for the LHCb Muon System are presented. The results are based on an accumulated charge of about 0.45 C/cm2^2, corresponding to about 4 years of LHCb running at the highest background rate. The performance of the chamber has been studied under several photon flux values exploiting a muon beam. A degradation of the rate capability above 1 kHz/cm2^2 is observed, which can be correlated to a sizeable increase of resistivity of the chamber plates. An increase of the chamber dark current is also observed. The chamber performance is found to fulfill the LHCb operation requirements.Comment: 6 pages, 9 figures, presented at the International Workshop on Aging Phenomena in Gaseous Detectors'', DESY-Hamburg (Germany), October 200

    Secondary Neutron and Photon Dose in Proton Therapy

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    Abstract Background and purpose : The dose due to secondary neutrons and photons in proton therapy was estimated with Monte Carlo simulations. Three existing facilities treating eye and deep-seated tumours were taken into account. The results of the calculations related to eye proton therapy were verified with measurements. Materials and methods : The simulations were performed with the FLUKA code. Neutron fluence was measured inside an Alderson phantom (type ART) with activation techniques. Results : The maximum dose due to secondaries produced in a passive beam delivery system was estimated to be of the order of 10 −4 and 10 −2 Gy per therapy Gy for eye and deep tumour treatments, respectively. In the case of irradiations of deep-seated tumours carried out with an active system, the dose was of the order of 10 −3 Gy per therapy Gy. Conclusions : The dose due to secondaries depends on the geometry of the beam delivery system and on the energy of the primary beam and is lower in the healthy tissues distant from the target volume

    New results from an extensive aging test on bakelite Resistive Plate Chambers

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    We present recent results of an extensive aging test, performed at the CERN Gamma Irradiation Facility on two single--gap RPC prototypes, developed for the LHCb Muon System. With a method based on a model describing the behaviour of an RPC under high particle flux conditions, we have periodically measured the electrode resistance R of the two RPC prototypes over three years: we observe a large spontaneous increase of R with time, from the initial value of about 2 MOhm to more than 250 MOhm. A corresponding degradation of the RPC rate capabilities, from more than 3 kHz/cm2 to less than 0.15 kHz/cm2 is also found.Comment: 6 pages, 7 figures, presented at Siena 2002, 8th Topical Seminar on Innovative Particle and Radiation Detectors 21-24 October 2002, Siena, Ital

    First evaluation of neutron induced single event effects on the CMS barrel muon electronics

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    Neutron irradiation tests of the currently available electronics for the CMS barrel muon detector were performed using Thermal and fast neutrons at E< 11MeV. The Single Event Upset rate on the Static RAM was measured, while upper limits are derived for events having experienced no failure. The results are used to guess the upper limits on the mean time between failures in the whole barrel muon detector
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