Literatura académica sobre el tema "Gamma beam diagnostics"

The ELI-NP (Extreme Light Infrastructure-Nuclear Physics) facility, currently under construction near Bucharest (Romania), is the pillar of the project ELI dedicated to the generation of high-brilliance gamma beams and high-power laser pulses that will be used for frontier research in nuclear physics. To develop an experimental program at the frontiers of the present-day knowledge, two pieces of equipment will be deployed at ELI-NP: a high power laser system consisting of two 10 PW lasers and a high brilliance gamma beam system. The ELI-NP Gamma beam system will deliver an intense gamma beam with unprecedented specifications in terms of photon flux, brilliance and energy bandwidth in an energy range from 0.2 to 20 MeV. Such a gamma beam requires special devices and techniques to measure and monitor the beam parameters during the commissioning and the operational phase. To accomplish this task, the Gamma Beam Characterization System, equipped with four elements, was developed: a Compton spectrometer (CSPEC), to measure and monitor the photon energy spectrum; a nuclear resonant scattering system (NRSS), for absolute beam energy calibration and inter-calibration of the other detectors; a beam profile imager (GPI) to be used for alignment and diagnostics purposes; and finally a sampling calorimeter (GCAL), for a fast combined measurement of the beam average energy and intensity. The combination of the measurements performed by GCAL and CSPEC allows fully characterizing the gamma beam energy distribution and intensity with a precision at the level of few per mill, enough to demonstrate the fulfillment of the required parameters. This article presents an overview of the gamma beam characterization system with focus on these two detectors, which were designed, assembled and are currently under test at INFN-Firenze. The layout and the working principle of the four devices is described, as well as some of the main results of detector tests.

The ELI-NP facility, currently being built in Bucharest, Romania, will deliver an intense and almost monochromatic gamma beam with tunable energy between 0.2 and 20 MeV. The challenging energy bandwidth of [Formula: see text]0.5% will be adjusted through the collimation system, while the main beam parameters will be measured through a devoted gamma-beam characterization system.[Formula: see text] The gamma-beam characterization system, designed by the EuroGammaS collaboration, consists of four elements: a Compton spectrometer that measures the gamma energy spectrum; a sampling calorimeter for a fast combined measurement of the beam average energy and its intensity, which will be used also as a monitor during machine commissioning and development; a nuclear resonant scattering system for absolute energy inter-calibration of the other detectors; and a gamma beam profile imager to be used for alignment and diagnostics purposes. The collimation and characterization system will be presented in this article. These systems have already been built and tested, while the delivery at ELI-NP facility and the final commissioning is scheduled by Fall 2018.

The paper presents the first experimental results obtained by using new gamma-quantum diagnostics for ion beam induced high energy density matter. Registration of γ-quantum output from the region of beam-target interaction with time resolution enables to pick-up information on density evolution of the target even if the ionization state of matter involved is unknown.

Analytical methods based on particle accelerators are widely used in cultural heritage diagnostics and archaeological sciences from the absolute dating of organic materials by means of radiocarbon accelerator mass spectrometry (AMS) to the analysis of the elemental composition of a wide range of materials (metals, obsidians, pottery) via ion beam analysis (IBA) techniques. At CEDAD (Centre for Dating and Diagnostics), the accelerator facility of the University of Salento, AMS 14C dating and PIXE (particle-induced X-ray emission)-PIGE (particle-induced gamma-ray emission) compositional analysis in external beam mode are combined to study certain archaeological materials. We present a review of the combined application of these analytical methods in the study of casting cores of the Riace bronzes, 2 classical Greek statues of extraordinary importance for the history of art.

We report on the technological commissioning of the Laser–Plasma Ion Accelerator section of the ELIMAIA user beamline at the ELI Beamlines facility in the Czech Republic. The high-peak, high-average power L3-HAPLS laser system was used with an energy of ~10 J and pulse duration of ~30 fs on target, both in single-pulse and high repetition-rate (~0.5 Hz) mode. The laser pulse was tightly focused to reach ultrahigh intensity on target (~1021 W/cm2) and sustain such laser–plasma interaction regime during high repetition-rate operations. The laser beam, ion beam, and laser–plasma emission were monitored on a shot-to-shot basis, and online data analysis at 0.5 Hz was demonstrated through the full set of used diagnostics (e.g., far and near field, laser temporal diagnostics, X- and gamma-ray detectors, Thomson Parabola ion spectrometer, time-of-flight ion detectors, plasma imaging, etc.). The capability and reliability of the ELIMAIA Ion Accelerator was successfully demonstrated at a repetition rate of 0.5 Hz for several hundreds of consecutive laser shots.

A TrueBeam STx is one of the most technologically advanced linear accelerators forradiotherapy and radiosurgery. The Monte Carlo simulation widely used in many applications in various fields such as nuclear physics, astrophysics, particle physics, and medicine. The Geant4/GATE Monte Carlo toolkit is developed for the simulation in imaging diagnostics, nuclear medicine, radiotherapy, and radiation biology to more accurately predict beam radiation dosimetry. In this work, we present the simulation results of the dosimetric characteristics of a 6 MV photon beam of TrueBeam STx medical LINAC using Monte Carlo Geant4/GATE. The percentage depth dose (PDD), central axis depth dose (Profile) have been simulated and compared with those measured in a water phantom for field sizes 10×10 cm2 via the gamma-index method. These results will permit to check calculation data given by the treatment planning system.

The possibility of organizing neutron therapy with a photoneutron beam produced by the electron accelerator target, and ensuring the required dose at the tumor at a reasonable exposure time and with minimal impact on patients investigated. Generation of neutrons from the target of electron accelerator takes place in two stages: e- ® γ ® n, and in the selected electron energy range of 20-100 MeV, the bremsstrahlung gamma radiation in many times (~ 3 orders of magnitude) offers more than “useful” neutron yield. This raises the problem of the selective control of the “harmful” for radiotherapy secondary gamma radiation while providing the minimum attenuation of the neutron flux in the output beam. In order to solve the general problem of the formation of a neutron beam with necessary spectral characteristics having sufficient intensity, there has been resolved a number of computational tasks of the selection of the optimal configuration of the output beam unit and its composition. The matter of high importance is to minimize additional irradiation of the patient from the bremsstrahlung (generated by electrons) and secondary gamma radiation (generated by neutrons) from the accelerator target as well as from output unit’s materials. On the other hand, at a generation stage e- ® γ the bremsstrahlung beam could be applied for effective radionuclide production by reactions (γ,n) and (γ,p) due to high leak intensity ~ 1.3·1017 photon/s. By the Mo100(γ,n)99Mo reaction the main diagnostic nuclide 99Tc could be produced sufficiently for the clinical needs. The resulting configuration of the output unit provides the required beam quality for the neutron capture therapy (NCT), which commonly assumed to be the only competitive technology of neutron therapy on the background of the massive invasion of proton therapy and other highly selective techniques that ultimately damage the target sparing the surrounding tissues and organs. For the accessible accelerator (average current 4 mA and electron energy 35 MeV) the flux density of epithermal photoneutrons (they required for NCT) in the beam at the output is of the order of magnitude or more higher than the typical yield from existing and planned reactors' beams. The proposed scheme of generation and extraction of photoneutrons for NCT has a number of strong advantages over traditional techniques: a) the applying of electron accelerators for neutron production is much safer and cheaper than conventional reactor beams in use; b) accelerator with the target, the beam output unit with the necessary equipment can be placed on the territory of the clinic without any problems of radiation safety; c) the proposed target – liquid gallium, which also serves as a cooler, is an “environmentally friendly” material due to low activation which rapidly (in ~ 4 days) falls to the background level.

Technologically-enhanced electronic image sensors are used in various fields as diagnostic techniques in medicine or space applications. In the latter case the devices can be exposed to intense radiation fluxes over time which may impair the functioning of the same equipment. In this paper we report the results of gamma-ray irradiation tests on CMOS image sensors simulating the space radiation over a long time period. Gamma-ray irradiation tests were carried out by means of IGS-3 gamma irradiation facility of Palermo University, based on 60Co sources with different activities. To reduce the dose rate and realize a narrow gamma-ray beam, a lead-collimation system was purposely built. It permits to have dose rate values less than 10 mGy/s and to irradiate CMOS Image Sensors during operation. The total ionizing dose to CMOS image sensors was monitored in-situ, during irradiation, up to 1000 Gy and images were acquired every 25 Gy. At the end of the tests, the sensors continued to operate despite a background noise and some pixels were completely saturated. These effects, however, involve isolated pixels and therefore, should not affect the image quality.

Particle beam radiography, which uses a variety of particle probes (neutrons, protons, electrons, gammas and potentially other particles) to study the structure of materials and objects noninvasively, is reviewed, largely from an accelerator perspective, although the use of cosmic rays (mainly muons but potentially also high-energy neutrinos) is briefly reviewed. Tomography is a form of radiography which uses multiple views to reconstruct a three-dimensional density map of an object. There is a very wide range of applications of radiography and tomography, from medicine to engineering and security, and advances in instrumentation, specifically the development of electronic detectors, allow rapid analysis of the resultant radiographs. Flash radiography is a diagnostic technique for large high-explosive-driven hydrodynamic experiments that is used at many laboratories. The bremsstrahlung radiation pulse from an intense relativistic electron beam incident onto a high-Z target is the source of these radiographs. The challenge is to provide radiation sources intense enough to penetrate hundreds of g/cm2 of material, in pulses short enough to stop the motion of high-speed hydrodynamic shocks, and with source spots small enough to resolve fine details. The challenge has been met with a wide variety of accelerator technologies, including pulsed-power-driven diodes, air-core pulsed betatrons and high-current linear induction accelerators. Accelerator technology has also evolved to accommodate the experimenters' continuing quest for multiple images in time and space. Linear induction accelerators have had a major role in these advances, especially in providing multiple-time radiographs of the largest hydrodynamic experiments.

Abstract The use of lead apron for radiation protection is regulated under the Indonesia Nuclear Regulatory Agency (BAPETEN) Decree no. 8 year 2011 about Radiation Safety and the Use of Diagnostic and Interventional Radiological X-Ray Machine. It listed the apron specifications are as follows: having thickness equivalent to 0.2 mm Pb or 0.25 mm Pb for diagnostic use and equivalent to 0.35 mm Pb or 0.5 mm Pb for interventional use. Further, National Standardization Agency (BSN) had issued SNI IEC 61331-1:2016, providing guidance for testing the plate materials on the apron using 400 kV x-ray machine and 1.3 MeV gamma exposure with narrow beam, to measure the attenuation ratio and air kerma rate. The method used is to determine the attenuation ratio, build-up factors, and equivalent attenuation coefficient. There were 4 different aprons (A, B, C, and D) with 9 measurement points. The results showed the air kerma rate without apron was 0.664 mGy/second, the air kerma rate with lead-equivalent layer was 0.0006 mGy/second, and the best result was produced using the apron C, with the attenuation ratio ranging from 17.2 to 29.1, showing the most homogeneity.

The ELI-NP (Extreme Light Infrastructure-Nuclear Physics) facility, currently under construction near Bucharest (Romania), is the pillar of the project ELI dedicated to the generation of high intensity gamma beams for frontier research in nuclear physics. To develop an experimental program at the frontiers of the present-day knowledge, two equipments will be deployed at ELI-NP: a high power laser system consisting of two 10 PW lasers and a high brilliance gamma beam system. The ELI-NP gamma beam will be obtained by collimating the radiation emerging from incoherent inverse Compton scattering of short laser pulses on relativistic electron beam bunches. Using this method it will be possible to obtain a gamma beam with unique characteristics in terms of brilliance, photon flux and energy bandwidth that are necessary to cover the proposed experiments in fundamental physics, nuclear physics and astrophysics, as well as applications in material and life sciences, industrial tomography and nuclear waste management. The system will consist of two energy lines: a low-energy line (LE) delivering gamma rays with energies up to 3.5 MeV and a high-energy line (HE) where the energy of the gamma rays will reach up to 19.5 MeV. Such a gamma beam requires peculiar devices and techniques to measure and monitor the beam parameters during the commissioning and the operational phase. To accomplish this task, a Gamma Beam Characterisation system equipped with four elements has been developed: a Compton spectrometer (CSPEC), to measure and monitor the photon energy spectrum; a nuclear resonant scattering spectrometer, for absolute beam energy calibration and intercalibration of the other detectors; a beam profile imager to be used for alignment and diagnostics purposes and finally a sampling calorimeter (GCAL), for a fast combined measurement of the beam average energy and intensity. The system must be able to cope with the time structure of the beam made by 32 pulses of 10^5 photons each, with a duration of 1-2 ps, separated by 16 ns and delivered at 100 Hz. The combination of the measurements performed by GCAL and CSPEC allows to fully characterize the gamma beam energy distribution and intensity with a precision of about 0.5%, enough to demonstrate the fulfillment of the required parameters. The work described in this thesis concerns the realization and the characterization of these two detectors, which are under construction at the INFN Firenze. The first detector described is the CSPEC, used to reconstruct the energy spectrum of the γ beam with a non-destructive method. The basic idea is to measure energy and position of electrons recoiling at small angles from Compton interactions of the beam, on a thin micro-metric mylar target. A high purity germanium detector (HPGe) will be used to precisely measure the energy of the Compton scattered electron, while a double sided silicon strip detector will determine the impact point of the e^- on the detector. The recoil photon is detected by Barium Fluoride (BaF2) crystals, whose fast response in coincidence with the HPGe signal will provide the trigger. The CSPEC is expected to reconstruct the γ beam energy spectrum with a precision of about the 0.1% on the reconstruction of the beam peak energy and width. The characterization procedure of the HPGe and the BaF2 detectors are presented in this thesis. The resolution on the beam energy measurement critically depends on the accuracy of the electron energy determination, which in turn is correlated to the HPGe energy resolution and to the energy loss in the materials preceding the HPGe active volume. We verified the excellent energy resolution and linearity of the HPGe by exposing the detector to different radioactive γ sources and obtaining a resolution of 0.156% at 1332 keV. In addition, the accuracy of the HPGe MC simulations, in particular of the parameters related to the dead layers preceding the HPGe crystal, has been verified using electrons of definite energy emitted by a 207^Bi source. The measured peak positions are in agreement with the simulated ones with a precision better than 1 keV confirming the correctness of the simulation geometry. The MC simulation describe well also the width of the peaks, for which we measured values that differ less than 0.4 keV from the expected ones. Concerning the CSPEC photon detector we implemented a signal shape identification method that use the ratio between the two light components of the BaF2 detector to discriminate between signals produced by γ and those due to α particles (the intrinsic radioactivity of the crystal) or to those due to thermal noise. We also characterized the crystals response in terms of linearity and energy resolution using different γ sources. In addition we verified that the BaF2 crystals intrinsic radioactivity can be used to infer changes in the energy calibration of the detector. The second detector subject of this thesis is the GCAL, a calorimeter providing a fast combined measurement of the beam average energy and intensity by absorbing the gamma pulses in a longitudinally segmented calorimeter. The intensity of the gamma beam is not exactly known, so the photon energy cannot be simply determined from the total energy released, as usually happens in calorimeters. The basic idea is to use properties of the gamma energy released inside the detector, that depends only on the photon energy and not on the beam intensity. This is obtained by exploiting the monotonic energy dependence of the total photon interaction cross section for low-Z materials in the energy range of interest at the ELI-NP facility. Thus, realizing a sampling calorimeter with low Z absorber, the average energy of the beam can be measured by fitting the longitudinal profile against parametrized distributions, obtained with detailed MC simulations. Once the photon energy is known, assuming a monochromatic beam, the number of impinging photons is obtained from the total energy released. The calorimeter for the LE beamline has been realized as a sampling calorimeter composed by 22 identical layers. Each element consists of a block of Polyethylene absorber (an inexpensive and easily workable low-Z material) followed by a readout board hosting 7 adjacent silicon detectors. The silicon detectors time response has been tested using an infrared laser. Indeed the time response is a critical issue, since the calorimeter has to be able to resolve the 16 ns separated pulses of the ELI-NP beam. This test has shown that the silicon sensors equipped with a fast custom electronics are able to disentangle pulses with the same time structure of the beam, with an accuracy at the level of per mill. The functionality of each sensor composing the calorimeter has been checked with an infrared laser. We verify the signal dependence from the γ impact point and that there are no anomalies on detector response, scanning the sensors horizontally and vertically. The last part of the activity has regarded the optimization of the calorimeter MC simulation. Starting from a simplified simulation used in the early stage of the project were there was no geometry details, new simulations were made considering a thorough description of the microstrip detectors (dead area, aluminum strip and backplane metallization) and including the presence of the aluminum supporting structures and of the acquisition board. The performances of the GCAL has been evaluated executing the energy reconstruction procedure on these new MC samples and indicate a statistical accuracy on the average beam energy and on the number of photons, better than few per mill after collecting data for a few seconds of beam operation. We have checked that the effect of the background particles is negligible given that the energy released from these particles is four order of magnitude smaller than the one released by the γ beam. The effects of some of the main sources of systematic uncertainties in the determination of the beam energy and intensity of the low-energy calorimeter have been investigated. We have studied the variations produced by having a γ beam with a characteristic energy spectrum and spatial distribution or with a random jitter on the beam energy (or intensity) rather than a monochromatic point-like beam and finally the effects related to incorrect inter-calibration of the different detector layers. The energy and intensity beam jitters do not deteriorate the GCAL performance and with a realistic beam, we obtained a reconstructed energy that is the average energy of the beam rather than the peak value in agreement with the calorimeter working principle. Due to the asymmetry on the low-energy side of the energy spectrum, the offset in the total energy deposited translates into an underestimation of the beam intensity. This effects can be accounted for by correctly simulating the beam energy distribution when producing the energy profiles. The main systematic effect turns out to be the miscalibration of the silicon pads that introduces a systematic shift on the values of the beam energy and intensity that amounts to about 0.5% for the energy and 0.7% for the intensity.

The Gamma Beam Source (ELI-NP-GBS) machine 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. The Linac will provide trains of 32 electron bunches in each RF pulse, separated by 16.1 ns; each bunch has a charge of 250 pC . The goal of my work is to propose a layout for a distributed energy measurement along the ELI-NP-GBS machine: this will be useful during the commissioning stage of the machine in order to verify the correct functionality of the newly design C-Band accelerating structures, due to the fact that there are OTR screens after each accelerating module. Furthermore, I have studied the feasibility of bunch by bunch energy measurement using a gated camera system.