Dissertations / Theses on the topic 'Charged particle radiation'
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1
Testa, Mauro. "Charged particle therapy, ion range verification, prompt radiation." Phd thesis, Université Claude Bernard - Lyon I, 2010. http://tel.archives-ouvertes.fr/tel-00566188.
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This PhD thesis reports on the experimental investigation of the prompt photons created during the fragmentation of the carbon beam used in particle therapy. Two series of experiments have been performed at the GANIL and GSI facilities with 95 MeV/u and 305 MeV/u 12C6+ ion beams stopped in PMMA and water phantoms. In both experiments a clear correlation was obtained between the C-ion range and the prompt photon profile. A major issue of these measurements is the discrimination between the prompt photon signal (which is correlated with the ion path) and a vast neutron background uncorrelated with the Bragg-Peak position. Two techniques are employed to allow for this photon-neutron discrimination: the time-of-flight (TOF) and the pulse-shape-discrimination (PSD). The TOF technique allowed demonstrating the correlation of the prompt photon production and the primary ion path while the PSD technique brought great insights to better understand the photon and neutron contribution in TOF spectra. In this work we demonstrated that a collimated set-up detecting prompt photons by means of TOF measurements, could allow real-time control of the longitudinal position of the Bragg-peak under clinical conditions. In the second part of the PhD thesis a simulation study was performed with Geant4 Monte Carlo code to assess the influence of the main design parameters on the efficiency and spatial resolution achievable with a multidetector and multi-collimated Prompt Gamma Camera. Several geometrical configurations for both collimators and stack of detectors have been systematically studied and the considerations on the main design constraints are reported.
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Koziel, Michal. "Development of radiation hardened pixel sensors for charged particle detection." Strasbourg, 2011. http://www.theses.fr/2011STRA6237.
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Les capteurs CMOS sont développés depuis une décennie en vue d’équiper les détecteurs de vertex des expériences de physique des particules à venir, avec les avantages d’un faible budget de matière et de bas coûts de production. Les caractéristiques recherchées sont un temps de lecture court, une granularité élevée et une bonne radiorésistance. Cette thèse est principalement consacrée à l’optimisation de ce dernier point. Pour diminuer le temps de cycle vers les 10 microsecondes, la lecture des pixels en parallèle dans chaque colonne a été implémentée, associée à une logique de suppression d’information des pixels sans signal. Les pixels sont devenus plus complexes et plus sensibles aux rayonnements ionisants. L’optimisation de l’architecture des pixels, par des techniques standard de durcissement aux rayonnements, a porté la limite à 300 krad (quelques Mrad attendus) pour le procédé de fabrication à 0,35-um utilisé jusque-là. L’amélioration de la tenue aux rayonnements ionisants passe par l’utilisation de technologies de taille inférieure à 0,35-um, naturellement plus radio-résistantes. Ceci facilitant de plus l’intégration de tous les composants dans un pixel. Un autre aspect abordé dans cette thèse concerne la tolérance aux rayonnements non ionisants. Différentes technologies CMOS améliorant la collecte de charges ont été testées. L’utilisation d’une couche de détection de haute résistivité a porté la tenue à ces rayonnements à 3•1013 neq/cm2, conforme à l’objectif fixé. Ce résultat marque une étape importante pour les capteurs CMOS qui devraient rapidement satisfaire le cahier des charges d’expériences particulièrement contraignantes telles que CBM par exempleCMOS Pixel Sensors are being developed since a few years to equip vertex detectors for future high-energy physics experiments with the crucial advantages of a low material budget and low production costs. The features simultaneously required are a short readout time, high granularity and high tolerance to radiation. This thesis mainly focuses on the radiation tolerance studies. To achieve the targeted readout time (tens of microseconds), the sensor pixel readout was organized in parallel columns restricting in addition the readout to pixels that had collected the signal charge. The pixels became then more complex, and consequently more sensitive to radiation. Different in-pixel architectures were studied and it was concluded that the tolerance to ionizing radiation was limited to 300 krad with the 0. 35-um fabrication process currently used, while the targeted value was several Mrad. Improving this situation calls for implementation of the sensors in processes with a smaller feature size which naturally improve the radiation tolerance while simultaneously accommodate all the in-pixel microcircuitry in small pixels. Another aspect addressed in this thesis was the tolerance to non ionizing radiation, with a targeted value of >1013 neq/cm2. Different CMOS technologies featuring an enhanced signal collection were therefore investigated. It was demonstrated that this tolerance could be improved to 3•1013 neq/cm2 by the means of a high-resistivity epitaxial layer. This achievement triggered a new age of the CMOS pixel sensors and showed that their development is on a good track to meet the requirements of the particularly demanding CBM experiment
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Wei, Xiaomin. "Study and improvement of radiation hard monolithic active pixel sensors of charged particle tracking." Phd thesis, Université de Strasbourg, 2012. http://tel.archives-ouvertes.fr/tel-00953382.
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Monolithic Active Pixel Sensors (MAPS) are good candidates to be used in High Energy Physics (HEP) experiments for charged particle detection. In the HEP applications, MAPS chips are placed very close to the interaction point and are directly exposed to harsh environmental radiation. This thesis focuses on the study and improvement of the MAPS radiation hardness. The main radiation effects and the research progress of MAPS are studied firstly. During the study, the SRAM IP cores built in MAPS are found limiting the radiation hardness of the whole MAPS chips. Consequently, in order to improve the radiation hardness of MAPS, three radiation hard memories are designed and evaluated for the HEP experiments. In order to replace the SRAM IP cores, a radiation hard SRAM is developed on a very limited area. For smaller feature size processes, in which the single event upset (SEU) effects get significant, a radiation hard SRAM with enhanced SEU tolerance is implemented by an error detection and correction algorithm and a bit-interleaving storage. In order to obtain higher radiation tolerance and higher circuitry density, a dual-port memory with an original 2-transistor cell is developed and evaluated for future MAPS chips. Finally, the radiation hardness of the MAPS chips using new available processes is studied, and the future works are prospected.
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Adkins, Raymond. "A LIQUID CRYSTAL BASEDELECTRON SHOWER DETECTOR." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1522427297703445.
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Kundu, Ashoke. "Monte Carlo simulation of gas-filled radiation detectors." Thesis, University of Surrey, 2000. http://epubs.surrey.ac.uk/987/.
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Harvey, Shaun. "Charged particle induced soft errors in 1 Mbit and 4 Mbit DRAMs as the basis for a portable radiation detector system." Thesis, University of Surrey, 1998. http://epubs.surrey.ac.uk/843953/.
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A portable high speed digital electronic DRAM radiation detection system was designed and constructed at the University of Surrey. The electronics system was designed around a Fully Programmable Gate Array (FPGA) acting as the DRAM controller. The system was controlled by a Personal Computer (PC) which also acquired and stored the data. The system control software was developed using the C language and written at the University of Surrey, the system was designed for use with 4 different types of Dynamic Random Access Memory (DRAM) chips acting as detectors mounted on separate boards from the controller. This was so that the main electronics could be placed in a shielded area whilst the detector is exposed to a radiation field. This is especially important in neutron fields where activation of components can be a significant problem. The radiation response of decapsulated 1 Mbit and 4 Mbit DRAMs to alpha particles was examined. There were six different devices in all, three 1 Mbit standard power devices, two 4 Mbit standard power devices and one 4 Mbit low power DRAM. These DRAMs were tested under different operating conditions of operating voltage, memory data pattern, cycle time and incident a-particle energy. Each DRAM was examined and their peak responses in terms of these factors was determined and compared to previous experiments with earlier DRAMs, all six devices were found to show an increase in soft error rate (SER) when the operating voltage of the DRAM was decreased. This was in agreement with previous experiments. This continued until an optimum was reached, if the operating was decreased below the optimum then the SER of the devices would quickly fall to zero, which was an unexpected effect. Two devices, the Hyundai 1 Mbit device and the Hitachi 4 Mbit ZIG-ZAG device exhibited a strong dependence on memory pattern with the Hyundai having no response with a 0000 pattern and a peak SER with a 1111 pattern. The Hitachi device had it's highest SER at 0000 and it's lowest at 1111. The other devices all exhibited some pattern dependence but it was not as marked as in these two devices. The devices all showed a lower SER for higher energy alpha particles (~5 MeV) with the SER increasing as the incident alpha particle energy decreased until a maximum SER was reached. As the incident energy was decreased further the SER would begin to fall again. This was also in agreement with previous DRAM experiments. The highest SER of the DRAMs tested was that of the 4 Mbit low power DRAM (manufactured by Toshiba), which had an SER of 224.25 s-1, more than 25 times that of the next most sensitive device, the 1 Mbit Hyundai standard power DRAM with a peak SER of 8.27 s-1. Unfortunately, due to an undetected fault in the low power header board the Toshiba device was not available to be used in the positron and neutron experiments. The 1 Mbit standard power devices (as they were more sensitive than the 4 Mbit standard power devices) were taken to the MRC Cyclotron Unit in London to try and detect a variety of positron emitters (11C, 15O, 18F 68Ge). Unfortunately, these experiments were not successful and the 1 Mbit devices did not appear to have enough sensitivity to be able to detect any of these particles. The 1 Mbit devices were also taken and irradiated in a neutron beam from the CONSORT-II research reactor at Imperial College, the devices were irradiated both bare and coated with a thermal neutron to charged particle converter material, the converter used was 6LiF and was deposited directly onto the bare silicon die of the DRAM, in both cases thermal neutrons were detected by the DRAMs. Further possible experiments with a larger range of low power DRAMs to investigate their apparently high SER rates are discussed, including further experiments with positrons and neutrons. The implications of further miniaturisation of the controller and header boards for remote inspection purposes are also discussed.
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Söderberg, Jonas. "Dosimetry and radiation quality in fast-neutron radiation therapy : a study of radiation quality and dosimetric properties of fast-neutrons for external beam radiotherapy and problems associated with corrections of measured charged particle cross-sections /." Linköping : Division of Radiation Physics, Department of Medicine and Care, Faculty of Health Science, Linköping University, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-8589.
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Söderberg, Jonas. "Dosimetry and radiation quality in fast-neutron radiation therapy : A study of radiation quality and basic dosimetric properties of fast-neutrons for external beam radiotherapy and problems associated with corrections of measured charged particle cross-sections." Doctoral thesis, Linköpings universitet, Medicinsk radiofysik, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-8589.
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The dosimetric properties of fast-neutron beams with energies ≤80 MeV were explored using Monte Carlo techniques. Taking into account transport of all relevant types of released charged particles (electrons, protons, deuterons, tritons, 3He and α particles) pencil-beam dose distributions were derived and used to calculate absorbed dose distributions. Broad-beam depth doses in phantoms of different materials were calculated and compared and the scaling factors required for converting absorbed dose in one material to absorbed dose in another derived. The scaling factors were in good agreement with available published data and show that water is a good substitute for soft tissue even at neutron energies as high as 80 MeV. The inherent penumbra and the fraction of absorbed dose due to photon interactions were also studied, and found to be consistent with measured values reported in the literature. Treatment planning in fast-neutron therapy is commonly performed using dose calculation algorithms designed for photon beam therapy. When applied to neutron beams, these algorithms have limitations arising from the physical models used. Monte Carlo derived neutron pencil-beam kernels were parameterized and implemented in the photon dose calculation algorithms of the TMS (MDS Nordion) treatment planning system. It was shown that these algorithms yield good results in homogeneous water media. However, the method used to calculate heterogeneity corrections in the photon dose calculation algorithm did not yield correct results for neutron beams in heterogeneous media. To achieve results with adequate accuracy using Monte Carlo simulations, fundamental cross-section data are needed. Neutron cross-sections are still not sufficiently well known. At the The Svedberg Laboratory in Uppsala, Sweden, an experimental facility has been designed to measure neutron-induced charged-particle production cross-sections for (n,xp), (n,xd), (n,xt), (n,x3He) and (n,xα) reactions at neutron energies up to 100 MeV. Depending on neutron energy, these generated particles account for up to 90% of the absorbed dose. In experimental determination of the cross-sections, measured data have to be corrected for the energies lost by the charged particles before leaving the target in which they were generated. To correct for the energy-losses, a computational code (CRAWL) was developed. It uses a stripping method. With the limitation of reduced energy resolution, spectra derived using CRAWL compares well with those derived using other methods. In fast-neutron therapy, the relative biological effectiveness (RBE) varies from 1.5 to 5, depending on neutron energy, dose level and biological end-point. LET and other physical quantities, developed within the field of microdosimetry over the past couple of decades, have been used to describe RBE variations between different fast-neutron beams as well as within a neutron irradiated body. In this work, a Monte Carlo code (SHIELD-HIT) capable of transporting all charged particles contributing to absorbed dose, was used to calculate energy-differential charged particle spectra. Using these spectra, values of the RBE related quantities LD, γD, γ* and R were derived and studied as function of neutron energy, phantom material and position in a phantom. Reasonable agreement with measured data in the literature was found and indicates that the quantities may be used to predict RBE variations in an arbitrary fast-neutron beam.
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Muggiolu, Giovanna. "Deciphering the biological effects of ionizing radiations using charged particle microbeam : from molecular mechanisms to perspectives in emerging cancer therapies." Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0599/document.
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Ces dernières années, le paradigme de la radiobiologie selon lequel les effets biologiques des rayonnements ionisants ne concernent strictement que les dommages à l'ADN et les conséquences liées à leur non réparation ou à leur réparation défectueuse, a été remis en question. Ainsi, plusieurs études suggèrent que des mécanismes «non centrés » sur l'ADN ont une importance significative dans les réponses radio-induites. Ces effets doivent donc être identifiés et caractérisés afin d’évaluer leurs contributions respectives dans des phénomènes tels que la radiorésistance, les risques associés au développement de cancers radio-induits, les conséquences des expositions aux faibles doses. Pour ce faire, il est nécessaire : (i) d'analyser la contribution de ces différentes voies de signalisation et réparation induites en fonction de la dose et de la zone d’irradiation; (ii) d’’étudier les réponses radio-induites suite à l’irradiation exclusive de compartiments subcellulaires spécifiques (exclure les dommages spécifiques à l'ADN nucléaire); (iii) d’améliorer la connaissance des mécanismes moléculaires impliqués dans les phénomènes de radiosensibilité/radiorésistance dans la perspective d’optimiser les protocoles de radiothérapie et d’évaluer in vitro de nouvelles thérapies associant par exemple les effets des rayonnements ionisants et de nanoparticules d’oxydes métalliques. Les microfaisceaux de particules chargées offrent des caractéristiques uniques pour répondre à ces questions en permettant (i) des irradiations sélectives et en dose contrôlée de populations cellulaires et donc l’étude in vitro des effets « ciblés » et « non ciblés » à l'échelle cellulaire et subcellulaire, (ii) de caractériser l’homéostasie de cultures cellulaires en réponses à des expositions aux rayonnements ionisants et/ou aux nanoparticules d’oxydes métalliques (micro-analyse chimique multi-élémentaire). Ainsi, au cours de ma thèse, j'ai validé et exploité des méthodes d’évaluation qualitatives et quantitatives (i) in cellulo et en temps réel de la réponse radio-induite de compartiments biologiques spécifiques (ADN, mitochondrie, …) ; (ii) in vitro de la radiosensibilité de lignées sarcomateuses issues de patients; et (iii) in vitro des effets induits par des expositions à des nanoparticules d'oxydes métalliques afin d’évaluer leur potentiel thérapeutique et anti-cancéreuxFew years ago, the paradigm of radiation biology was that the biological effects of ionizing radiations occurred only if cell nuclei were hit, and that cell death/dysfunction was strictly due to unrepaired/misrepaired DNA. Now, next this “DNA-centric” view several results have shown the importance of “non-DNA centered” effects. Both non-targeted effects and DNA-targeted effects induced by ionizing radiations need to be clarified for the evaluation of the associated radiation resistance phenomena and cancer risks. A complete overview on radiation induced effects requires the study of several points: (i) analyzing the contribution of different signaling and repair pathways activated in response to radiation-induced injuries; (ii) elucidating non-targeted effects to explain cellular mechanisms induced in cellular compartments different from DNA; and (iii) improving the knowledge of sensitivity/resistance molecular mechanisms to adapt, improve and optimize the radiation treatment protocols combining ionizing radiations and nanoparticles. Charged particle microbeams provide unique features to answer these challenge questions by (i) studying in vitro both targeted and non-targeted radiation responses at the cellular scale, (ii) performing dose-controlled irradiations on a cellular populations and (iii) quantifying the chemical element distribution in single cells after exposure to ionizing radiations or nanoparticles. By using this tool, I had the opportunity to (i) use an original micro-irradiation setup based on charged particles microbeam (AIFIRA) with which the delivered particles are controlled in time, amount and space to validate in vitro methodological approaches for assessing the radiation sensitivity of different biological compartments (DNA and cytoplasm); (ii) assess the radiation sensitivity of a collection of cancerous cell lines derived from patients in the context of radiation therapy; (iii) study metal oxide nanoparticles effects in cells in order to understand the potential of nanoparticles in emerging cancer therapeutic approaches
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Appelt, Eric. "Measurements of Charged-Particle Transverse Momentum Spectra in PbPb Collisions at Square Root of SNN = 2|76 TeV and in pPb Collisions at Square Root of SNN = 5|02 TeV with the CMS Detector." Thesis, Vanderbilt University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3584408.
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Warren, Daniel Rosevear. "Proton radiotherapy uncertainties arising from computed tomography." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:ab59f596-e277-490a-a7c1-1cb81b47b9a9.
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Proton radiotherapy is a cancer treatment which has the potential to offer greater cure rates and/or fewer serious side effects than conventional radiotherapy. Its availability in the UK is currently limited to a single low-energy fixed beamline for the treatment of ocular tumours, but a number of facilities designed to treat deep-seated tumours are in development. This thesis focusses on the quantitative use of x-ray computed tomography (CT) images in planning proton radiotherapy treatments. It arrives at several recommendations that can be used to inform clinical protocols for the acquisition of planning scans, and their subsequent use in treatment planning systems. The primary tool developed is a software CT scanner, which simulates images of an anthropomorphic virtual phantom, informed by measurements taken on a clinical scanner. The software is used to investigate the accuracy of the stoichiometric method for calibrating CT image pixel values to proton stopping power, with particular attention paid to the impact of beam hardening and photon starvation artefacts. The strength of the method adopted is in allowing comparison between CT-estimated and exactly-calculated proton stopping powers derived from the same physical data (specified in the phantom), leading to results that are difficult to obtain otherwise. A number of variations of the stoichiometric method are examined, identifying the best-performing calibration phantom and CT tube voltage (kVp). Improvements in accuracy are observed when using a second-pass beam hardening correction algorithm. Also presented is a method for identifying the proton paths where stopping power uncertainties are likely to be greatest. Estimates of the proton range uncertainties caused by CT artefacts and calibration errors are obtained for a range of realistic clinical scenarios. The current practice of including planning margins equivalent to 3.5% of the range is found to ensure coverage in all but the very worst of cases. Results herein suggest margins could be reduced to <2% if the best-performing protocol is followed; however, an analysis specific to the CT scanner and treatment site in question should be carried out before such a change is made in the clinic.
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Mossuz, Laurence. "Etude de la production et de la désintégration semi-électronique de particules charmées dans les diffusions inélastiques de neutrinos." Université Joseph Fourier (Grenoble), 1997. http://www.theses.fr/1997GRE10087.
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Cette these presente une etude de la production et de la desintegration semi-electronique des particules charmees dans la diffusion profondement inelastique de neutrinos mu. L'analyse est basee sur l'ensemble des evenements mu- e+, selectionnes a partir des donnees enregistrees par l'experience nomad dans le faisceau de neutrinos du cern au cours de l'annee 1995. Afin de reduire drastiquement le bruit de fond des evenements mu- e+, nous avons elabore une premiere selection sur les donnees. Puis, une etude d'evenements neutrinos simules dans nomad nous a permis de controler la qualite de la simulation, et d'affiner la selection sur les donnees. Nous avons mesure un signal charme mu- e+. Le nombre total de candidats mu- e+, ainsi que ses distributions cinematiques sont sensibles a la structure interne du nucleon. Par comparaison des distributions cinematiques du signal extrait sur les donnees et des evenements charmes simules, nous avons mesure le contenu en quarks etranges du nucleon. La these comporte une partie instrumentale principalement sur le detecteur a rayonnement de transition (drt), qui contribue a l'identification des electrons dans l'experience. Cependant, pour utiliser au mieux ses capacites de discrimination l'uniformite de la reponse de l'ensemble de ses elements est necessaire. Ce travail a permis d'une part de mesurer et d'ajuster l'uniformite du drt sur l'ensemble de la surface de ses 9 plans, et d'autre part d'etre a meme de controler en permanence cette uniformite au cours de la prise de donnees.
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Jung, Yun Su. "Effects of charge distribution within a particle beam on the sub-Cerenkov radiation." Thesis, Monterey, California: U.S. Naval Postgraduate School, 1987. http://hdl.handle.net/10945/22767.
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The charge distribution of periodic electron beam pulses generates patterns of sub-Cerenkov radiation distinctive of the distribution of charge with in a bunch. Mapping the radiation pattern from different charge shapes may provide insight into whether charge pulse shapes can be determined from observed radiation patterns. The radiation patterns of Gaussian, Level, and Trapezoidal function were mapped by computer simulation. Near 90 degree to the beam, the radiation patterns of all three charge distributions developed an envelope proportional to the fourier transform of the charge bunch distribution when the wavelength of the emitted radiation was comparable to the size of the bunch. For the Gaussian function, the envelope is Gaussian, for the level function it is a sinc function. Since the envelope for the trapezoidal function in the product of two sinc functions it is more difficult to analyze. This work may provide a basis for determining the charge shape of electron beam pulses from the sub-Cerenkov radiation based on the radiation intensity pattern
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Strube, Jan 1978. "Analysis of radiative decays of charged B mesons to baryonic final states." Thesis, University of Oregon, 2008. http://hdl.handle.net/1794/9022.
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xxvi, 199 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.The abundance of B mesons at B factories opens the door to the search in rare decays for physics outside of the Standard Model. Flavor-changing neutral current transitions proceed only via higher order in the Standard Model, resulting in a b [arrow right] s³y branching fraction of about 3 x 10 -4 , but hypothesized particles could alter the rate significantly. Decays of B mesons that proceed via this electroweak penguin diagram are an interesting example of flavor-changing neutral currents, due to the large number of accessible final states with observables that are sensitive to new processes. This dissertation describes the analyses of such decays B - [arrow right] p ³, B - [arrow right] £ 0 p ³, B - [arrow right] p and B - [arrow right] p using about 350 million B meson pairs recorded by the BABAR detector in the years 2001 through 2006. In addition to the decay rate, the distribution of the invariant mass of the baryon pair is presented, using a method for statistical unfolding. The analysis is the first of these decays at the BABAR experiment and lays the groundwork for future analyses of the branching fractions and angular correlations of b [arrow right] s decays containing A hyperons and other baryons at BABAR or higher luminosity B factories.
Adviser: James E. Brau
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Ozturk, Fahri. "Scalar Mesons In Radiative Phi-meson Decays Into Charged K-meson States." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609614/index.pdf.
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The role of $f_{0}(980)$ and
$a_{0}(980)$ scalar meson intermediate states in the mechanism of
radiative $phi (1020)$ meson decay into two charged $K (494)$
mesons and a photon $phirightarrow K^{+} + K^{-} + gamma$ is
investigated. For the contribution of scalar meson intermediate
state two models are considered. In the kaon-loop model, the scalar
meson intermediate state couples the final state to the initial
$phi$ meson through a charged kaon-loop. The second model, called
no-structure model, consist of point-like coupling of intermediate
scalar meson state to the initial state. It is found that in the
kaon-loop model, scalar meson intermediate state results in a
considerable modification of the pure Bremsstrahlung photon
spectrum.
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McGarry, Stephen. "Irradiated silicon particle detectors." Thesis, Lancaster University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369468.
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Ogul, Hasan. "Studies of muon efficiencies for measurement of W charge asymmetry in inclusive pp → W (muupsilon) production at s = 7 TeV." Thesis, The University of Iowa, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1545468.
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The main motivation of the Compact Muon Solenoid (CMS) experiment is to explore and to discover physics underlying electro-weak asymmetry breaking. Beside this, CMS detector provides an opportunity to do various experiments for detecting new physics signatures beyond the Standard Model (SM). Investigation of these signatures requires the identification and precise energy and moment measurement of electrons, muons, photons, and jets. The objective of this thesis is the calculation of the efficiencies for the measurement of W charge asymmetry in inclusive pp → W (&mgr;υ) production. The charge asymmetry is defined to be the difference between W + and W− bosons, normalized to the sum. This asymmetry is sensitive to the u-quark and d-quark ratios in the proton and precise measurement of the W charge asymmetry can provides new insights to the proton structure functions. Therefore, to improve understanding of SM backgrounds in search for new physics, the moun trigger, isolation, reconstruction, identification efficiencies has been studied using partial data collected by the CMS detector during pp collisions at the LHC in 2011. The dataset corresponds to an integrated luminosity of 2.31 fb−1. The efficiencies are measured as functions of the decay muon pseudo rapidity and transverse momentum based on "tag and probe" method. The efficiency measurements are compared to their estimated value from the Monte Carlo simulations so as to provide scaling factors to correct to the residual mis-modeling of the CMS muon performance. The comparison with simulations based on MC simulations opens a gate for validation of the detector simulation and optimization of selection strategies.
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Mahee, Durude. "Numerical Simulation and Graphical Illustration of Ionization by Charged Particles as a Tool toward Understanding Biological Effects of Ionizing Radiation." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1535381068931831.
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Burmistrov, Leonid. "A detector for charged particle identification in the forward region of SuperB." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00673482.
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In this thesis, we present the conception, the performances studies and the first tests in the Cosmic Muon Telescope situated at SLAC of a new detector for the particle identification in the forward region of the SuperB detector.This detector is based on time-of-flight (TOF) technique. To identify the particles with momentum up to 3 GeV/c and flight base around two meters we need a TOF detector able to measure the time with a precision of about 30 ps. To achieve this goal we have conceived a device producing Cherenkov light in a fused silica (quartz) radiator, by a charged particle, which then detected with very fast photodetectors and dedicated ultrafast electronics. We call it, the DIRC-like TOF detector.For what concern the photodetectors, the HAMAMATSU SL-10 MCP-PMT has been characterized at LAL test bunch and the time resolution of about 37 ps has been measured. The new 16-channel USB WaveCatcher electronics developed by LAL (CNRS/IN2P3) and CEA/IRFU has shown to have a jitter of less than 10 ps. The geometry of the quartz detector has been then carefully studied with Geant4 simulation. Which shows that the best detector geometry allow to reach the time resolution of about 90 ps per photoelectron with at least 10 photoelectrons detected, giving in average the desired 30 ps total time resolution.We have constructed a prototype of such device, using the quartz bars available from the Babar experiment, and we have installed it, in the SLAC Cosmic Ray Telescope. A time resolution of about 70 ps per photoelectron was obtained, in agreement with simulation.This proof-of-principle has convinced the SuperB Collaboration to adopt such a device as the baseline for the SuperB particle identification detector in the forward region. The delicate point which is still opened is the resistance of this detector to the machine background.In this thesis we also present preliminary studies of different types of background and their effect on the performances of the DIRC-like TOF detector. Radiative Bhabha process is by far the dominant source of background. The rate of the background photoelectrons caused mainly by the gammas with energy around 1.4 MeV is estimated to be ~480 kHz/cm^2 which corresponds to 2 C/cm^2 of integrated anode charge in 5 years. The neutron flux thought the DIRC-like TOF front end electronics is ~10^11/cm^2/year. These preliminary results are reassuring.
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Fomin, Alex. "Multiple Scattering Effects on the Dynamics and Radiation of Fast Charged Particles in Crystals. Transients in the Nuclear Burning Wave Reactor." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS272/document.
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Les effets cohérents dans l’interaction des particules à haute énergie avec les cristauxouvrent de nouvelles opportunités d’accélération et détection de particules. Les champs électromagnétiquesefficaces présents dans les cristaux qui se présentent dans ce cas peuvent dépassermille fois les champs qui sont maintenant réalisables dans les installations expérimentales.La première partie de la thèse est consacrée à l’étude théorique des effets de diffusion multiples surla dynamique et le rayonnement des particules chargées de haute énergie dans les cristaux. L’undes objectifs de cette étude est de trouver des conditions optimales pour effectuer la mesure dumoment magnétique anormal du baryon Lamda au LHC. En raison de la courte durée de vie de cetteparticule, le seul moyen de fournir une telle mesure est d’utiliser un cristal courbé, qui peut imiter lechamp magnétique de l’ordre de milliers de Tesla.L’optimisation des paramètres du set up expérimental a été réalisée sur la base de la simulation parordinateur du passage du Baryon Lamda à travers un cristal courbé à l’aide du modèle de collisions binaires, entenant compte de la diffusion incohérente sur les vibrations thermiques des atomes des noeuds enréseau et de la diffusion sur un sous-système électronique d’un cristal. Les résultats de la recherchemenée dans la thèse démontre la possibilité d’effectuer une telle expérience au LHC et sont devenusla base de la proposition correspondante.Les effets de diffusion multiple des électrons ultra relativistes et le rayonnement des positons dansles cristaux alignés sont également considérés dans la première partie de la thèse.Il est également démontré que la distribution angulaire spectrale et les caractéristiques de polarisationdu rayonnement diffèrent essentiellement des résultats de la théorie de Bethe–Heitler. Lesconditions d’observation expérimentale de ces effets sont présentées.La deuxième partie de la thèse est consacrée à l’étude des processus transitoires des réacteursrapides fonctionnant dans un régime d’onde de combustion nucléaire auto-entretenue (OCN). C’estun nouveau concept de réacteurs de fission nucléaire avec la soi-disant “sécurité intrinsèque”, danslaquelle le développement d’une réaction nucléaire à chaîne incontrôlable est impossible en raisondes principes physiques du fonctionnement du réacteur. Les concepts prometteurs du réacteur OCNdans le cas de sa mise en œuvre permettent d’utiliser l’uranium appauvri et fournit le traitement desdéchets radioactifs à longue durée de vie.Cette étude est basée sur la résolution numérique de l’équation de diffusion non linéaire non stationnairedu transport de neutrons avec un ensemble d’équations de combustion pour les composantsdu carburant et les équations de la cinétique nucléaire pour les noyaux précurseurs des neutronsretardés, en utilisant une approche “effective multigroup”. Le modèle du réacteur cylindrique homogèneavec le combustible métallique des cycles de carburant U–Pu, Th–U et mixte Th–U–Pu estconsidéré dans le cadre du concept de flambage.À la suite de ces études, l’existence du mode OCN dans le cas du combustible mixte Th–U–Puet de ses avantages essentiels est démontrée; l’analyse détaillée d’un type spécial de rétroactionnégative inhérente au régime OCN et sous-jacente à la “sécurité intrinsèque” d’un tel réacteur esteffectuée; les scénarios d’un démarrage en douceur, d’un arrêt forcé et d’un redémarrage ultérieurdu réacteur OCN sont développésThe coherent effects in the high energy particle interaction with crystals open up new opportunities for accelerating and detecting techniques. The effective electromagnetic fields that arise in this case can exceed a thousand times the fields that are now attainable at experimental installations. The first part of the thesis is devoted to the theoretical study of the multiple scattering effects on the dynamics and radiation of high energy charged particles in crystals. One of the goals of this study is to find optimal conditions to carry out the measurement of the anomalous magnetic moment of the charmed Lambda Baryon at the LHC. Due to the short lifetime of this particle the only way to provide such a measurement is to use a bent crystal, which can imitate the magnetic field of order of thousand Tesla. The optimization of the parameters for an experimental setup was carried out on the basis of computer simulation of the Lamda Baryon passage through a bent crystal using the binary collisions model, taking in to account incoherent scattering on thermal vibrations of atoms at lattice nodes, and scattering on an electronic subsystem of a crystal. The results of the research conducted in the thesis give an optimistic forecast for the possibility of carrying out such an experiment at the LHC and became the basis of the corresponding proposal. The multiple scattering effects of the thesis. This study is performed in the framework of classical electrodynamics approach for describing the relativistic particle radiation and the computer simulation of fast charged particles passing through a crystal using the above-mentioned model. It is shown, that the spectral-angular distribution and the polarization characteristics of radiation essentially differ from the results of the Bethe–Heitler theory. The conditions for the experimental observation of these effects are presented. The second part of the thesis is devoted to the study of transient processes in advanced fast reactor breeder working in a self-sustained nuclear burning wave (NBW) regime. It is a new concept of nuclear fission reactors with the so-called “intrinsic safety”, in which the development of uncontrolled chain nuclear reaction is impossible due to the physical principles of reactor operation. The promising concepts of NBW reactor in the case of its implementation allows to utilize the depleted Uranium and provides the treatment of long-lived radioactive waste. This study is based on numerical solving the non-stationary non-linear diffusion equation of neutron transport together with a set of the burn-up equations for fuel components and the equations of nuclear kinetics for precursor nuclei of delayed neutrons using effective multi-group approach. The model of cylindrical homogeneous reactor with metallic fuel of U–Pu, Th–U and mixed Th–U–Pufuel cycles is considered in the framework of the buckling concept. As a result of these studies the existence of the NBW mode in the case of mixed Th–U–Pu fuel and its essential advantages are demonstrated; the detailed analysis of a special kind of the negative reactivity feedback that is inherent to the NBW regime and underlies the “intrinsic safety” of such a reactor is performed; the scenarios of a smooth start-up, forced shutdown and subsequent restart of the NBW reactor are developed
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Lalucaa, Valérian. "Etude des effets singuliers produits par les particules énergétiques chargées de l’environnement radiatif spatial sur les capteurs d’images CMOS." Thesis, Toulouse, ISAE, 2013. http://www.theses.fr/2013ESAE0042/document.
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Ce mémoire de thèse traite des effets singuliers produits par les milieux radiatifs sur les capteurs d’images CMOS. Le travail se concentre sur les effets provoqués par les ions lourds sur les capteurs utilisant des pixels 3T à photodiode standard et des pixels 4T et 5T à photodiodes pincées. Dans un premier temps, l’étude se concentre sur l’environnement spatial et l’architecture des capteurs. La comparaison avec la littérature met en évidence les effets les plus critiques sur les capteurs : le SEL et les SET. Les capteurs testés expérimentalement valident les travaux théoriques. Les SET sont comparés aux simulations de l’outil de modélisation STARDUST, et montrent un bon accord pour toutes les puces et les ions. Il est expliqué pourquoi les SET sur les puces 3T sont insensibles aux variations de conception de la photodiode, et pourquoi l’utilisation d’un substrat épitaxié diminue grandement les SET. Une méthode de réduction des SET est implémentée avec succès sur les puces 4T et 5T, et le composant responsable du latchup est identifié. L’ensemble des mécanismes explorés permet de connaitre les paramètres importants pour durcir les imageursThis thesis studies the single event effects of space environment in CMOS image sensors (CIS). This work focuses on the effects of heavy ions on 3T standard photodiode pixels, and 4T and 5T pinned photodiode pixels. The first part describes the space radioactive environment and the sensor architecture. The most harmful events (SEL and SETs) are identified thanks to the scientific literature. The experimentally tested sensors agree with the theoretical work. SETs are compared to STARDUST simulations with a good agreement for all ions and sensors. The work explains why the SETs on 3T pixels are insensitive to the various photodiode designs, and they are decreased when an epitaxial substrate is used. A method using anti-blooming was successfully used in 4T and 5T pixels to prevent the spread of the SETs. The mechanism of latchup in 4T pixel sensors is described. All the identified mechanisms are very useful to provide hardening methods for the CISs
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Haas, Benjamin. "QCD sur réseau et physique du charme." Paris 11, 2009. http://www.theses.fr/2009PA112359.
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Dans cette thèse, nous présentons les résultats des études sur les propriétés de la physique du charme sur le réseau. Nous utilisons des configurations unquenched et une action de quark de type Wilson (Wilson-clove et Wilson twisted). Nous avons étudié la désintégration du meson D* et calculés la valeur du couplage hadronique g_{D* D\pi}$$ et du couplage $$g_{D^\ast D\gamma}$$. Nous avons également étudiés la désintégration leptonic et semilleptonic du méson Ds. Nous avons pu contraindre les éléments $$\vert V_{cd}\vert$$ et $$\vert V_{cs} \vert$$ de la matrice CKMLn this thesis, we present the results of the study of the charm properties on the lattice. We used unquenched configuration with Wilson-like actions, i. E. Wilson--Clover and twisted-mass quark actions. We studied the decay of the $$D"\ast$$ meson and computed the coupling hadronic coupling $$g_{D"\ast D\pi}$$,the radiative coupling $$g_{D"\ast D\gamma}$$. We then studied the leptonic and semileptonic of the $$D_{(s)}$$-mesons. We constrained the CKM matrix entries $$\vert V_{cd} \vert$$ and $$\vert V_{cs} \vert$$
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Moreau, Thomas. "Etude numérique et développement de spectromètres embarquables de particules chargées." Toulouse 3, 2003. http://www.theses.fr/2003TOU30032.
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Bhat, Siddharth. "Design and characterization in depleted CMOS technology for particle physics pixel detector." Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0267.
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L’expérience ATLAS commencera à fonctionner avec l’accélérateur LHC à hauteluminosité (HL-LHC) en 2026 pour augmenter la probabilité de nouvelles découvertes. La technologie du détecteur de pixels monolithiques en "depleted" CMOS a été une des options envisagées pour la couche externe du détecteur pixel d’ATLAS mis a niveau et est une technologie à fort potentiel pour les futurs détecteurs a pixels. Dans cette thèse, plusieurs prototypes ont été développés utilisant différentes technologies CMOS appauvries, par exemple, LFoundry (LF) 150 nm, TowerJazz (TJ) à 180 nm et Austriamicrosystems AG (AMS) à 180 nm. Dans un environnement à haute énergie, tel que HL-LHC, les événements uniques (SEU), qui deviennent un sujet de préoccupation pour le bon fonctionnement des circuits. Plusieurs puces de test dans les technologies AMS, TowerJazz et LFoundry avec différentes structures tolérantes au SEU ont été prototypées et testées. Un schéma d’alimentation alternatif appelé schéma d’alimentation série est prévu pour le futur détecteur Inner Tracker (ITk) de l’expérience ATLAS. Pour répondre aux exigences de l’expérience ATLAS concernant l’environnement d’une couche pixélisée dans un environnement de collisionneur à rayonnement élevé, de nouveaux développements avec des capteurs "depleted" CMOS ont été développés dans le régulateur Shunt-LDO et la polarisation de capteur conçus dans la technologie d’imagerie CMOS TowerJazz 0,18 um modifiée. Dans le processus TowerJazz modifié, deux niveaux de tension différents sont utilisés pour l'épuisement du capteur. Polarisation les tensions sont générées à l'aide d'un circuit de pompe à charge négativeThe ATLAS experiment will start operating at the High Luminosity LHC accelerator (HL-LHC) in 2026 to increase the probability of new discoveries. Depleted CMOS monolithic pixel detector technology has been one of the options considered for the outer layer of an upgraded ATLAS pixel detector and is a high potential technology for future pixel detectors. In this thesis, several prototypes have been developed using different depleted CMOS technologies, for instance, LFoundry (LF) 150 nm, TowerJazz (TJ) 180 nm and austriamicrosystems AG (AMS) 180 nm. In a high-energy environment like HL-LHC, Single Event Upsets (SEU), which become of concern for reliable circuit operation. Several test-chips in AMS, TowerJazz and LFoundry technologies with different SEU tolerant structures have been prototyped and tested. The SEU tolerant structures were designed with appropriate electronics simulations using Computer Aided Design (CAD) tools in order to study the sensitivity of injected charge to upset a memory state. An alternative powering scheme named Serial Powering scheme is foreseen for the future Inner Tracker (ITk) detector of the ATLAS experiment. To meet the requirements ofthe ATLAS experiment to the environment of a pixelated layer in a high radiation collider environment, new developments with depleted CMOS sensors have been made in Shunt-LDO regulator and sensor biasing which are designed in modified TowerJazz 180 nm CMOS imaging technology. In the TowerJazz modified process, two different voltage levels are used for the purpose of sensor depletion. The bias voltages are generated by using a negative charge pump circuit
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Na, Dong-Yeop NA. "Electromagnetic Particle-in-Cell Algorithms on Unstructured Meshes for Kinetic Plasma Simulations." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1543398838970791.
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Keane, Aidan J. "Liouville's equation and radiative acceleration in general relativity." Thesis, University of Glasgow, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301358.
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Le, Foulher Fabrice. "Simulations Monte Carlo et mesures de l’émission de gamma prompts appliquées au contrôle en ligne en hadronthérapie." Thesis, Lyon 1, 2010. http://www.theses.fr/2010LYO10180/document.
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Au cours du traitement d'une tumeur avec des ions légers, la position du pic de Bragg doit être connue avec précision. Une fraction importante des ions incidents subissent des collisions nucléaires avec les noyaux cibles conduisant à l'émission de particules promptes qui peuvent être porteuses d'informations sur le parcours des ions. Ce travail, qui se concentre sur les gamma prompts, montre que le rendement en profondeur de ces émissions est fortement corrélé au parcours des ions et que les taux de comptage mesurés permettent d'envisager un système d'imagerie réaliste, fonctionnant en temps réel. Dans ce but, nous avons réalisé des expériences au GANIL et au GSI avec un détecteur collimaté placé perpendiculairement à l'axe du faisceau et la technique du temps de vol a été utilisée pour réduire le bruit de fond induit par les neutrons et les particules chargées. Des simulations Geant4 ont été réalisées pour concevoir le dispositif expérimental et interpréter les données. Un accord qualitatif entre les simulations et l'expérience est observé pour la quantité d'énergie déposée dans le détecteur et pour la forme du spectre de temps de vol. Cependant, des divergences apparaissent pour le rendement de gamma prompts et la distribution en profondeur des gamma détectés. Ces divergences sont discutées, principalement en termes de modèles de physique nucléaire qui doivent être améliorés. Après avoir sélectionné les modèles physiques offrant les simulations les plus en accord avec les mesures, des études concernant les lieux d'émissions des gamma prompts et l'influence de la diffusion dans la cible ont été réalisés afin de déterminer l'impact sur la corrélation avec le parcours des ionsDuring the treatment of a tumor with light ions, the Bragg peak location must be accurately known. A significant fraction of the incident ions undergo nuclear collisions with the target nuclei leading to the prompt emission of particles which may carry information on the ion path. This work, which focuses on prompt gamma, shows that the depth profile of these emissions is highly correlated to the ions path and the measured counting rates allow to consider a realistic imaging system, operating in real time. For that purpose, we performed experiments at GANIL and at GSI with a collimated detector placed perpendicular to the beam axis and the time of flight technique was used in order to reduce the noise induced by neutrons and charged particles. Geant4 simulations were performed for the experimental design and data interpretation. A qualitative agreement between simulations and experiment is observed for the amount of energy deposited in the detector and the shape of the time of flight spectrum. However, discrepancies appear for the prompt gamma yield and the depth distribution of gamma detected. These discrepancies are discussed, mainly in terms of nuclear physics models that must be improved. After selecting the physical models which lead to the best agreement between simulations and measurements, studies on the location of prompt gamma emission and on the influence of diffusion in the target were performed to determine the impact on the correlation with the ion path
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Scielzo, Nicholas David. "Measurement of the beta-neutrino correlation in laser trapped {sup 21}Na." Berkeley, Calif. : Oak Ridge, Tenn. : Lawrence Berkeley National Laboratory ; distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2003. http://www.osti.gov/servlets/purl/821455-YDxgQ2/native/.
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Thesis (Ph.D.); Submitted to Univ. of California, Berkeley, CA (US); 1 Jun 2003.Published through the Information Bridge: DOE Scientific and Technical Information. "LBNL--54350" Scielzo, Nicholas David. USDOE Director. Office of Science. Nuclear Physics (US) 06/01/2003. Report is also available in paper and microfiche from NTIS.
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Beaucourt-Jacquet, Céline. "Étude expérimentale du guidage du faisceau d’électrons dans le cadre de l’allumage rapide de cibles de fusion." Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14741/document.
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Les travaux de cette thèse s’inscrivent dans le cadre de l’allumage rapide pour la fusion par confinement inertiel (FCI), pour la production d’énergie. Dans ce schéma les phases de compression et d’allumage sont découplées. Au cours de la seconde phase, le faisceau d’électrons doit parcourir une distance de 300 µm dans le combustible dense avantde déposer son énergie au coeur de la cible et d’initier les réactions de fusion. Le principal défaut de ce schéma réside dans la divergence du faisceau d’électrons au cours de son transport dans la matière dense. Parmi plusieurs schémas proposés pour réduire cette divergence, nous considérons ici, les schémas sans cône basés sur la collimation des électrons dans un champ magnétique. En particulier, A.P.L. Robinson et ses collaborateurs [Phys. Rev. Lett. 100, 025002, 2008] ont proposé une méthode simple à mettre en place pour contrôler la divergence du faisceau d’électrons :utiliser une séquence de deux impulsions laser. La première impulsion permet de créer un environnement magnétique favorable au confinement du faisceau d’électrons engendré par la seconde interaction. La validation de cette proposition est le sujet de cette thèse. Nous présenterons les résultats expérimentaux et les modélisations théoriques motivées par cette proposition. L’expérience du guidage d’un faisceau d’électrons avec deux impulsions laser a été réalisée sur l’installation laser petawatt Vulcan au Rutherford Appleton Laboratory (RAL) à Didcot en Angleterre. Elle est basée sur la proposition d’un groupe international dans le cadre du projet FCI HiPER. Cette expérience nous a permis d’obtenir les conditions de guidage en fonction du rapport des intensités et du délai entre les deux impulsions. Les résultats de l’expérience ont été modélisés par le code hydrodynamique CHIC couplé au module de transport de particules chargées M1. L’interprétation des résultats expérimentaux nous a permis d’expliquer la base de la physique du guidage du faisceau d'électrons et d'en définir les conditions magnétiques favorablesThe work presented in this thesis is realised in the framework of the fast ignition of inertial confinement fusion for energy production. In this scheme the compression and the ignition phases are decoupled. During the second phase, the electron beam must cross over 300 µm in the dense fuel to deposit its energy in the dense core and ignite the fusion reactions.The major problem of the scheme is related to the divergence of the electron beam while it crosses the dense matter. Among the different propositions to inhibit the electron divergence we consider here the schemes without cone that are based on the effect of magnetic collimation. In particular, A.P.L. Robinson and his co-authors [Phys. Rev. Lett. 100, 025002, 2008] suggested a simple way to control the electron beam divergence by using a sequence of two laser pulses. The first one creates a magnetic background favourable for the confinement of the second electron beam resulting from the second interaction. The validation of this scheme is the major goal of this thesis.We present the results of experimental sudies and numerical modeling of the electron beam guiding with help of two consequent laser pulses. The experiment was performed on the Vulcan facility at the Rutherford Appleton Laboratory at Didcot in UK, based on the proposal submitted by an international group of scientists in the framework of the European project for inertial fusion energy HiPER. This experiment allowed us to define a combination of laser and target parameters where the electron beam guiding takes place. The analysis of experimental data and numerical modelling is realised with the hydrodynamic code CHIC coupled to the charged particules transport module M1. The interpretation of the experimental results allowed us to explain the experimental data and the physical basis of guiding and to define the magnetic conditionflavourable to the electron beam guidance
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Torrens, Caldentey Gabriel. "Estudio de eventos transitorios inducidos por radiación en memorias SRAM nanométricas." Doctoral thesis, Universitat de les Illes Balears, 2012. http://hdl.handle.net/10803/97291.
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Los efectos de la radiación en circuitos electrónicos se conocen desde los comienzos de la carrera espacial en los años 60, pues fuera de la atmósfera terrestre se está expuesto a niveles más altos de radiación que en la superficie. Sin embargo, el escalado de la tecnología electrónica ha conllevado un aumento de su susceptibilidad a la radiación, que puede desembocar en errores de funcionamiento incluso a nivel de tierra. Esta tesis estudia un efecto de la radiación, en memorias SRAM (Static Random Access Memory), denominado evento transitorio, que se caracteriza por corromper los datos almacenados en la memoria sin dañarla permanentemente. Se estudian por simulación diversas técnicas para diseñar memorias más robustas frente a eventos transitorios. Además, se ha diseñado y fabricado un prototipo de SRAM que incorpora algunas de estas técnicas. Finalmente, se ha validado experimentalmente su eficacia mediante la irradiación controlada del circuitoRadiation effects in electronic circuits are known since the beginning of the space race in the 1960s, because out of the terrestrial atmosphere, radiation exposure level is higher than on the surface. However, electronic technology scaling has led to an increase in radiation susceptibility that can result in operation errors even at ground level. This thesis deals with a radiation effect, in SRAMs (Static Random Access Memory), named transient event, which is characterized by corrupting data stored in the memory without causing any permanent damage to it. Several techniques to design more robust memories against radiation effects are studied by simulation. In addition, an SRAM prototype, including some of these techniques, has been designed and manufactured. Finally, the effectiveness of these techniques has been experimentally validated through controlled irradiation of the circuit.
Els efectes de la radiació en circuits electrònics es coneixen des dels inicis de la carrera espacial als anys 60, ja que fora de l’atmosfera terrestre s’està exposat a nivells més alts de radiació que a la superfície. No obstant això, l’escalat de la tecnologia electrònica ha comportat un augment de la susceptibilitat a la radiació, que pot desembocar en errors de funcionament fins i tot a nivell de terra. Aquesta tesi estudia un efecte de la radiació, en memòries SRAM (Static Random Access Memory), anomenat event transitori, que es caracteritza per corrompre les dades emmagatzemades a la memòria sense danyar-la permanentment. S’estudien per simulació diverses tècniques per dissenyar memòries més robustes en front a events transitoris. A més, s’ha dissenyat i fabricat un prototipus d’SRAM que incorpora alguna d’aquestes tècniques. Finalment, s’ha validat experimentalment la seva eficàcia mitjançant la irradiació controlada del circuit.
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Alhakeem, Eyad Ali. "Dosimetry at extreme non-charged particle equilibrium conditions using Monte Carlo and specialized dosimeters." Thesis, 2018. https://dspace.library.uvic.ca//handle/1828/10123.
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Radiotherapy is used in clinics to treat cancer with highly energetic ionizing particles. The radiation dose can be measured indirectly by means of radiation detectors or dosimeters. The dose deposited in a detector can be related to dose deposited in a point within the patient. In theory, however, this is only possible under charged particle equilibrium (CPE). The motivation behind the dissertation was driven by the difficult, yet crucial, dosimetry in non-CPE regions. Inaccurate dose assessment performed with standard dosimetry using ionization chambers may significantly impact the outcomes of radiotherapy treatments. Therefore, advanced dosimetry methods tailored specifically to suit non-CPE conditions must be used. This work aims to improve dosimetry in two types of non-CPE conditions that pose dosimetric challenges: regions near interfaces of tissues with low- and high- density media and in small photon fields.
To achieve the main dissertation objectives, an enhanced film dosimetry protocol with a novel film calibration approach was implemented. This calibration method is based on the percent depth dose (PDD) tables and was shown to be efficient and accurate. As a result, the PDD calibration method was used for the film dosimetry process throughout the dissertation work.
Monte Carlo (MC) calculations for the small field dosimetry were performed using phase-space files (PSFs) provided by Varian for TrueBeam linac. The MC statistical uncertainty in these types of calculations is limited by the number of particles (due to latent variance) in the used PSFs. This study investigated the behaviour of the latent variances (LV) with beam energy, depth in phantom, and calculation resolution (voxel size). LV was evaluated for standard 10x10 cm2 fields as well as small fields (down to 1.3 mm diameter). The results showed that in order to achieve sub-percent LV in open 10x10 cm2 field MC simulations a single PSF can be used, whereas for small SRS fields (1.3—10 mm) more PSFs (66—8 PSFs) would have to be summed.
The first study in this dissertation compared the performance of several dosimetric methods in three multi-layer heterogeneous phantoms with water/air, water/lung, and water/steel interfaces irradiated with 6 and 18 MV photon beams. MC calculations were used, along with Acuros XB, anisotropic analytical algorithm (AAA), GafChromic EBT2 film, and MOSkin dosimeters. PDDs were calculated and measured in these heterogeneous phantoms. The result of this study showed that Acuros XB, AAA, and MC calculations were within 1% in the regions with CPE. At media interfaces and buildup regions, differences between Acuros XB and MC were in the range of +4.4% to -12.8%. MOSkin and EBT2 measurements agreed to MC calculations within ~ 2.5%-4.5%. AAA did not predict the backscatter dose from the high-density heterogeneity. For the third, multilayer lung phantom, 6 MV beam PDDs calculated by all treatment planning system (TPS) algorithms were within 2% of MC. 18 MV PDDs calculated by Acuros XB and AAA differed from MC by up to 3.2 and 6.8%, respectively. MOSkin and EBT2 each differed from MC by up to 3%. All dosimetric techniques, except AAA, agreed within 3% in the regions with particle equilibrium. Differences between the dosimetric techniques were larger for the 18 MV than the 6 MV beam. This study provided a comparative performance evaluation of several advanced dosimeters in heterogeneous phantoms. This combination of experimental and calculation dosimetry techniques was used for the first time to evaluate the dose near these interfaces.
The second study in the dissertation aims to improve dose measurement accuracy in small radiotherapy fields. Field output factors of 6 MV beams from TrueBeam linear accelerator (linac) collimated with 1.27-40 mm diameter cones were calculated and measured using MC and EBT3 films. A set of detector specific correction factors for two widely used dosimeters (EFD-3G diode and PTW-60019 microDiamond detectors) were determined based on GafChromic EBT3 film measurements and calculated using MC methods. MC calculations were performed for microDiamond detector in parallel and perpendicular orientations relative to the beam axis. The result of this study showed that the measured OFs agreed within 2.4% for fields ≥10 mm. For the cones of 1.27, 2.46, and 3.77 mm diameter maximum differences were 17.9%, 1.8% and 9.0%, respectively. MC calculated OF in water agreed with those obtained using EBT3 film within 2.2% for all fields. MC calculated output correction factors for microDiamond detector in fields ≥10 mm ranged within 0.975-1.020 for perpendicular and parallel orientations. MicroDiamond detector correction factors calculated for the 1.27, 2.46 and 3.77 mm fields were 1.974, 1.139 and 0.982 with detector in parallel orientation, and these factors were 1.150, 0.925 and 0.914 in perpendicular orientation. EBT3 and MC obtained correction factors agreed within 3.7% for fields of ≥3.77 mm and within 5.9% for smaller cones. This work provided output correction factors for microDiamond and EFD-3G detectors in very small fields of 1.27 – 3.77 mm diameter and demonstrated over and under-response of these detectors in such fields. These correction factors allow improve the accuracy of dose measurements in small photon fields using these detectors.Graduate
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Schwab, John H. "Prolonged alterations of cardiomyocyte gene expression following low dose high charge and energy particle radiation--implications for future deep space travel." Thesis, 2015. https://hdl.handle.net/2144/16289.
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INTRODUCTION: Space exploration is ultra-hazardous and unpredictably dangerous. One area of significant concern is the exposure of astronauts to deep space radiation and the development of deleterious health effects. Earth's magnetic field and atmosphere both act to deflect the majority of deep space radiation, protecting humans on the surface of earth as well as astronauts in low Earth orbit missions. Because this type of radiation is not encountered terrestrially, very limited evidence exists in regards to the effects on the well-being. Deep space radiation, which consists of high charge and energy (HZE) particles, may be experimentally reproduced for studies using a particle accelerator. The long-term degenerative effects of cosmic irradiation on the cardiovascular system are vastly unknown. Detailing the molecular response within cardiomyocytes after exposure to HZE irradiation will provide needed knowledge for scientists to accurately assess the cardiovascular risks associated with deep space radiation exposure.
OBJECTIVE: The primary objective of this study is to characterize the molecular alterations of gene expression within murine cardiomyocytes following exposure to two different types of HZE.
METHODS: Wild type C57B1/6NT (Taconic) mice were exposed to either 90 cGy, 1 GeV proton (1H) or 15 cGy, 1 GeV/nucleon iron (56Fe) HZE particle-radiation. Radiation exposure was performed at the NASA Space Radiation Laboratory located at the Brookhaven National Laboratory (Upton, NY). Biological samples were taken and transcriptome profiling was performed at various time points following irradiation (1, 3, 7, 14, and 28 days).
RESULTS: Samples exposed to 56Fe-IR displayed significant levels of gene modulation, while proton-irradiation failed to elicit significant alterations in cardiomyocyte gene transcription compared to sham-irradiated samples. Network pathway analysis of iron-irradiated samples identified multiple biological pathways being significantly modulated. These biological pathways included cell death and survival, free radical scavenging, and inflammatory processes. Multiple points of upstream transcription regulation were identified as key nodes for regulating downstream expression. Validation of the signal transduction network by protein analysis showed that particle-IR clearly regulates a long lived signaling mechanism for p38 MAPK signaling and NFATc4 activation. Electrophoresis mobility shift assays supported the role of transcription factors GATA-4, STAT-3 and NF-𝜅B as key regulators.
CONCLUSIONS: The molecular response to 56Fe-IR is unique and induces long-term modulations of gene expression in cardiomyocytes that last up to at least 28 days following radiation exposure. However, exposure to 1H-IR failed to elicit significantly robust alterations in gene expression in cardiomyocytes. Additionally, proteins involved in signal transduction and transcriptional activation via DNA binding play a significant role in the molecular response following HZE particle radiation. This study may have multiple implications for NASA's efforts to develop cardio-degenerative risk estimates for astronauts participating in future deep space missions. By identifying molecular mechanisms and potential molecular markers, scientists can begin to assess excess relative risks and develop strategies to mitigate risks of developing physiological changes which may compromise future missions. This study may also have major safety implications for the increasing number of patients receiving conventional and particle radiotherapy.
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Bouchami, Jihène. "Mesure des champs de radiation dans le détecteur ATLAS et sa caverne avec les détecteurs au silicium à pixels ATLAS-MPX." Thèse, 2013. http://hdl.handle.net/1866/9704.
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Les collisions proton-proton produites par le LHC imposent un environnement radiatif hostile au détecteur ATLAS. Afin de quantifier les effets de cet environnement sur la performance du détecteur et la sécurité du personnel, plusieurs simulations Monte Carlo ont été réalisées. Toutefois, la mesure directe est indispensable pour suivre les taux de radiation dans ATLAS et aussi pour vérifier les prédictions des simulations. À cette fin, seize détecteurs ATLAS-MPX ont été installés à différents endroits dans les zones expérimentale et technique d'ATLAS. Ils sont composés d'un détecteur au silicium à pixels appelé MPX dont la surface active est partiellement recouverte de convertisseurs de neutrons thermiques, lents et rapides.
Les détecteurs ATLAS-MPX mesurent en temps réel les champs de radiation en enregistrant les traces des particules détectées sous forme d'images matricielles. L'analyse des images acquises permet d'identifier les types des particules détectées à partir des formes de leurs traces. Dans ce but, un logiciel de reconnaissance de formes appelé MAFalda a été conçu. Étant donné que les traces des particules fortement ionisantes sont influencées par le partage de charge entre pixels adjacents, un modèle semi-empirique décrivant cet effet a été développé. Grâce à ce modèle, l'énergie des particules fortement ionisantes peut être estimée à partir de la taille de leurs traces. Les convertisseurs de neutrons qui couvrent chaque détecteur ATLAS-MPX forment six régions différentes. L'efficacité de chaque région à détecter les neutrons thermiques, lents et rapides a été déterminée par des mesures d'étalonnage avec des sources connues.
L'étude de la réponse des détecteurs ATLAS-MPX à la radiation produite par les collisions frontales de protons à 7TeV dans le centre de masse a montré que le nombre de traces enregistrées est proportionnel à la luminosité du LHC. Ce résultat permet d'utiliser les détecteurs ATLAS-MPX comme moniteurs de luminosité. La méthode proposée pour mesurer et étalonner la luminosité absolue avec ces détecteurs est celle de van der Meer qui est basée sur les paramètres des faisceaux du LHC. Vu la corrélation entre la réponse des détecteurs ATLAS-MPX et la luminosité, les taux de radiation mesurés sont exprimés en termes de fluences de différents types de particules par unité de luminosité intégrée. Un écart significatif a été obtenu en comparant ces fluences avec celles prédites par GCALOR qui est l'une des simulations Monte Carlo du détecteur ATLAS. Par ailleurs, les mesures effectuées après l'arrêt des collisions proton-proton ont montré que les détecteurs ATLAS-MPX permettent d'observer la désintégration des isotopes radioactifs générés au cours des collisions. L'activation résiduelle des matériaux d'ATLAS peut être mesurée avec ces détecteurs grâce à un étalonnage en équivalent de dose ambiant.The LHC proton-proton collisions create a hard radiation environment in the ATLAS detector. In order to quantify the effects of this environment on the detector performance and human safety, several Monte Carlo simulations have been performed. However, direct measurement is indispensable to monitor radiation levels in ATLAS and also to verify the simulation predictions. For this purpose, sixteen ATLAS-MPX devices have been installed at various positions in the ATLAS experimental and technical areas. They are composed of a pixelated silicon detector called MPX whose active surface is partially covered with converter layers for the detection of thermal, slow and fast neutrons. The ATLAS-MPX devices perform real-time measurement of radiation fields by recording the detected particle tracks as raster images. The analysis of the acquired images allows the identification of the detected particle types by the shapes of their tracks. For this aim, a pattern recognition software called MAFalda has been conceived. Since the tracks of strongly ionizing particles are influenced by charge sharing between adjacent pixels, a semi-empirical model describing this effect has been developed. Using this model, the energy of strongly ionizing particles can be estimated from the size of their tracks. The converter layers covering each ATLAS-MPX device form six different regions. The efficiency of each region to detect thermal, slow and fast neutrons has been determined by calibration measurements with known sources. The study of the ATLAS-MPX devices response to the radiation produced by proton-proton collisions at a center of mass energy of 7TeV has demonstrated that the number of recorded tracks is proportional to the LHC luminosity. This result allows the ATLAS-MPX devices to be employed as luminosity monitors. To perform an absolute luminosity measurement and calibration with these devices, the van der Meer method based on the LHC beam parameters has been proposed. Since the ATLAS-MPX devices response and the luminosity are correlated, the results of measuring radiation levels are expressed in terms of particle fluences per unit integrated luminosity. A significant deviation has been obtained when comparing these fluences with those predicted by GCALOR, which is one of the ATLAS detector simulations. In addition, radiation measurements performed at the end of proton-proton collisions have demonstrated that the decay of radionuclides produced during collisions can be observed with the ATLAS-MPX devices. The residual activation of ATLAS components can be measured with these devices by means of ambient dose equivalent calibration.
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Gutierrez, Andrea. "Étude de la réponse du détecteur ATLAS-MPX aux neutrons rapides." Thèse, 2009. http://hdl.handle.net/1866/3785.
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Les détecteurs ATLAS-MPX sont des détecteurs Medipix2-USB recouverts de convertisseurs de fluorure de lithium et de polyéthylène pour augmenter l’efficacité de détection des neutrons lents et des neutrons rapides respectivement. Un réseau de quinze détecteurs ATLAS-MPX a été mis en opération dans le détecteur ATLAS au LHC du CERN.
Deux détecteurs ATLAS-MPX de référence ont été exposés à des sources de neutrons rapides 252 Cf et 241 AmBe ainsi qu’aux neutrons rapides produits par la réaction 7Li(p, xn) pour l’étude de la réponse du détecteur à ces neutrons. Les neutrons rapides sont principalement détectés à partir des protons de recul des collisions élastiques entre les neutrons et l’hydrogène dans le polyéthylène. Des réactions nucléaires entre les neutrons et le silicium produisent des particules-α. Une étude de l’efficacité de reconnaissance des traces des protons et des particules-α dans le détecteur Medipix2-USB a été faite en fonction de l’énergie cinétique incidente et de l’angle d’incidence. L’efficacité de détection des neutrons rapides a été évaluée à deux seuils d’énergie (8 keV et 230 keV) dans les détecteurs ATLAS-MPX. L’efficacité de détection des neutrons rapides dans la région du détecteur couverte avec le polyéthylène augmente en fonction de l’énergie des neutrons : (0.0346 ± 0.0004) %, (0.0862 ± 0.0018) % et (0.1044 ± 0.0026) % pour des neutrons rapides de 2.13 MeV, 4.08 MeV et 27 MeV respectivement.
L’étude pour déterminer l’énergie des neutrons permet donc d’estimer le flux des neutrons quand le détecteur ATLAS-MPX est dans un champ de radiation inconnu comme c’est le cas dans le détecteur ATLAS au LHC.ATLAS-MPX detectors are Medipix2-USB detectors covered with lithium fluoride and polyethylene converters in order to increase the detection efficiency of slow neutrons and fast neutrons respectively. A network of fifteen ATLAS-MPX detectors has been put in operation in the ATLAS detector at CERN-LHC. Two reference detectors ATLAS-MPX were exposed to two fast neutrons sources 252 Cf and 241 AmBe as well as fast neutrons produced by the reaction 7 Li( p, xn) for the study of the detector response to those neutrons. Fast neutrons are primarily detected by recoil protons from elastic collisions between neutrons and hydrogen in the polyethylene. In addition, α -particles are produced by nuclear reactions between neutrons and silicon. A study of the efficiency of proton and alpha particle track recognition of Medipix2-USB was done as a function of the initial kinetic energy and incidence angle. The detection efficiency of fast neutrons was evaluated for two energy thresholds (8 keV and 230 keV) of ATLAS-MPX detector. The fast neutron detection efficiency of the detector region covered in polyethylene increases with neutron energy: (0.0346 ± 0.0004) %, (0.0862 ± 0.0018) % and (0.1044 ± 0.0026) % for fast neutrons of 2.13 MeV, 4.08 MeV and 27 MeV respectively. The method for the measurement of neutron energy allows an estimate of the neutron flux when the ATLAS MPX detector is in an unknown radiation field as it is the case in the ATLAS detector at LHC.