Quando uma partícula carregada em movimento uniforme cruza a superfície entre dois meios de propriedades eletromagnéticas diferentes, ela emite a chamada Radiação de Transição (RT). Esta radiação tem espectro amplo, com emissão inclusive no intervalo de radiação visível. Esse processo de produção de radiação tem sido muito empregado em sistemas de monitoramento de feixes em aceleradores de partículas, por ser um processo que responde linearmente à carga que cruza a superfície e por permitir o monitoramento de diversos parâmetros do feixe em um único ponto de observação. Neste trabalho é apresentado o desenvolvimento de um sistema de monitoramento baseado em RT no intervalo óptico para operar em baixas energias de feixe de elétrons (próximas de 2 MeV) e realizar o diagnóstico de parâmetros importantes do feixe na entrada do primeiro estágio de aceleração do Mícrotron do IFUSP. / Transition Radiation (TR) is emitted when a charged particle moving with constant velocity, crosses the boundary between two media with different electromagnetic properties. This radiation is emitted in an wide spectral range, including the optical interval. This physical process has been used in beam diagnostic devices in particle accelerators due to its linear response to the charge that crosses the boundary and also because it allows the measurement of several beam parameters in a single observation point. In this work, we present the design of a device based on TR in the optical range to operate with low energy beams (about 2 MeV). The device enables the determination of the transverse phase space and of the fractional momentum deviation of the beam at the end of the linac, allowing the determination of important beam parameters at the entrance to the Microtron Booster.

Neste trabalho apresentamos o projeto do microtron principal do IFUSP. Inicialmente são apresentados os fundamentos teóricos relativos à estabilidade do feixe em um microtron, bem como discussões sobre a ótica do feixe. No trabalho são feitas basicamente 3 tipos de simulações distintas: simulação da dinâmica longitudinal e transversal da etapa síncrona, simulação da dinâmica transversal das linhas de transferência (inserção e extração) e a simulação relativa à otimização do projeto dos eletroímãs principais. As simulações longitudinais mostraram que é possível reduzir a energia de entrada do microtron principal de 4,9 para 2,5 MeV, o que permitira a eliminação do primeiro estágio síncrono (microtron booster). A energia final do microtron principal passa a ser 38 MeV. Foram realizados os projetos de duas linhas de inserção no principal para essas as duas energias (2,5 e 4,9 MeV) e foi feita uma análise comparativa desses dois projetos. O projeto da linha de extração também foi analisado levando em consideração duas energias de extração (5,8 e 38 MeV) para se mostrar a viabilidade dessa etapa. / In this work we present the design of the IFUSP main microtron. Initially, the theoretical foundations for the beam stability in the microton are presented as well as the beam optics is discussed. Three different kinds of simulations were done: Longitudinal and transversal beam dynamics in the synchronous part of the machine, transversal beam dynamics concerning the transfer lines and simulations related to the design of the main magnets. The longitudinal simulations sugested that it is possible to reduce the initial energy of the main microtron from 4.9 to 2.5 MeV, this would permit the elimination of the first synchronous stage (booster microtron). The final energy of the main microtron will be 38 MeV. The design of two insertion lines in the main microtron for the two different energies (2.5 and 4.9 MeV) was done and a comparative analysis between these two designes is presented. The design of the extraction line also takes into account two different extraction energies (5.8 and 38 MeV) in order to show de viability of this part.

Neste trabalho apresentamos o projeto, construção e testes de eletroímãs dipolares usados na linha de transporte do feixe do Microtron do IFUSP. Inicialmente são feitos estudos da contribuição do campo de borda dos eletroímãs na curvatura total do feixe e posteriormente esses valores foram usados para a definição de parâmetros de projeto. Foram construídos e caracterizados dois dipolos (30 e 45o) e ainda um eletroímã seletor (+/- 90o) com simetria azimutal. Os resultados obtidos nos testes realizados com os dipolos mostraram um desempenho adequado à operação do acelerador. Também é descrito um método para a simulação da trajetória de elétrons na presença de um campo magnético. / In this work we present the design, construction and testing of dipole magnets used on the beam line of IFUSP-Microtron. Initially we studied the fringe field of the magnets on the total beam bending, these values had been used for the definition of design parameters. It has been constructed two dipoles (30 and 45o) as well as a switch magnet (+/- 90o) with azimuthal symmetry. The tests results of the dipoles had shown an adequate performance to the accelerators operation. A method for the simulation of the electron path in the presence of a magnetic field is also described.

This thesis contains both physics analysis and hardware studies. It consists of two primary sections: the results of a search for heavy Majorana mass neutrinos, using the event signature of same (like) sign charged electron pairs ($e^{\pm} e^{\pm}$ ) and two jets, and the results of studies to upgrade the Hadronic Forward (HF) and Hadronic Endcap (HE) subdetectors in the Compact Muon Solenoid (CMS) detector in response to the high intensity proton-proton collisions generated at the Large Hadron Collider (LHC) at European Organization for Nuclear Research (CERN, Conseil Europ\'{e}en pour la Recherche Nucl\'{e}aire). In this search for Majorana mass neutrinos, same sign dielectron ($e^{\pm} e^{\pm}$) + dijet events in the final state have been considered as a signature for neutrino particles. The analyzed data corresponds to an integrated luminosity of 19.7 fb\textsuperscript{-1} of proton-proton collisions at a center of mass energy of \begin{math}\sqrt{s} = 8\ TeV \end{math}, collected using the CMS detector during the 2012 operation at the LHC. Monte Carlo simulations accounting for the theoretical expectations of the Standard Model (SM) and the detector limitations are used to prototype the experiment and to test proposed analysis steps. No excess of events is observed in the data beyond the expected SM background. Upper limits are set on the mixing element squared, $|{V}_{eN}|^{2}$, of the heavy Majorana neutrino with standard model neutrinos, as a function of Majorana neutrino mass for masses in the range of 40-500 $GeV/c^2$. The detector upgrade search comprises three sections of this thesis. The first section describes the test results of 1785 multianode Hamamatsu R7600U-200-M4 photomultiplier tubes (PMT) in numerous parameters such as gain, dark current, and timing characteristics, which provide insights on the expected performance of the upgraded CMS-HF detector. These PMTs replaced the previous single anode R7525 PMTs because the glass windows of previous PMTs are the source of Cherenkov radiation, which causes a background noise in the experiment. The second section reports characterization results of two types of PMTs in a novel operation mode for Secondary Emission (SE) Ionization Calorimetry, which is a novel technique to measure electromagnetic shower particles in extreme radiation environments. The third section presents the test results of novel scintillating materials for CMS experiment in specific and future particle accelerators in general. These materials are Polyethylene Naphthalate (PEN), Polyethylene Terephthalate (PET), high efficiency mirror (HEM) and quartz plates with various organic and inorganic coating materials such as p-Terphenyl (pTp), Anthracene and Gallium-doped Zinc Oxide (ZnO:Ga). We have investigated them for radiation hardness, light yield, timing characteristics, and scintillation and transmission properties.

A helicon plasma source is a device that can efficiently ionize a gas to create high density, low temperature plasma. There is growing interest in utilizing a helicon plasma source in propulsive applications, but it is not yet known if the helicon plasma source is able to function as both an ion source and ion accelerator, or whether an additional ion acceleration stage is required. In order to evaluate the capability of the helicon source to accelerate ions, the acceleration and ionization processes must be decoupled and examined individually. To accomplish this, a case study of two helicon thruster configurations is conducted. The first is an electrodeless design that consists of the helicon plasma source alone, and the second is a helicon ion engine that combines the helicon plasma source with electrostatic grids used in ion engines. The gridded configuration separates the ionization and ion acceleration mechanisms and allows for individual evaluation not only of ion acceleration, but also of the components of total power expenditure and the ion production cost. In this study, both thruster configurations are fabricated and experimentally characterized. The metrics used to evaluate ion acceleration are ion energy, ion beam current, and the plume divergence half-angle, as these capture the magnitude of ion acceleration and the bulk trajectory of the accelerated ions. The electrode-less thruster is further studied by measuring the plasma potential, ion number density, and electron temperature inside the discharge chamber and in the plume up to 60 cm downstream and 45 cm radially outward. The two configurations are tested across several operating parameter ranges: 343-600 W RF power, 50-450 G magnetic field strength, 1.0-4.5 mg/s argon flow rate, and the gridded configuration is tested over a 100-600 V discharge voltage range. Both configurations have thrust and efficiency below that of contemporary thrusters of similar power, but are distinct in terms of ion acceleration capability. The gridded configuration produces a 65-120 mA ion beam with energies in the hundreds of volts that is relatively collimated. The operating conditions also demonstrate clear control over the performance metrics. In contrast, the electrodeless configuration generally produces a beam current less than 20 mA at energies between 20-40 V in a very divergent plume. The ion energy is set by the change in plasma potential from inside the device to the plume. The divergence ion trajectories are caused by regions of high plasma potential that create radial electric fields.. Furthermore, the operating conditions have limited control of the resulting performance metrics. The estimated ion production cost of the helicon ranged between 132-212 eV/ion for argon, the lower bound of which is comparable to the 157 eV/ion in contemporary DC discharges. The primary power expenditures are due to ion loss to the walls and high electron temperature leading to energy loss at the plasma sheaths. The conclusion from this work is that the helicon plasma source is unsuitable as a single-stage thruster system. However, it is an efficient ion source and, if paired with an additional ion acceleration stage, can be integrated into an effective propulsion system.

In external electron beam therapy arbitrarily shaped inserts (cutouts) are used to define the contours of the irradiated field. This thesis describes the implementation and verification of a software system to calculate output factors for cutouts using Monte Carlo simulations. The design goals were: (1) A stand-alone software system running on a single workstation. (2) Task oriented graphical user interface with shape input capability. (3) Implementation on Mac OS XRTM (10A.x Tiger). (4) CPU multicore support by job splitting. (5) EGSnrc (Patch level V4-r2-2-5) for particle transport and dose scoring. (6) Validation for clinical use. / The system, called Cutout Manager, can calculate output factors with 1% statistical error in 20 minutes on Mac Pro computer (Intel XeonRTM, 4 cores). When the BEAMnrc linac model correctly reproduces percentage depth doses in the buildup region and around R100, calculated and measured output factors are in good agreement with precision measurements of circular cutouts at 100 cm source-to-surface distance (SSD) and extended SSD. Cutout Manager simulations are consistent with measurements of clinical cutouts within a 2% error margin.

Experiment E683 at Fermi National Accelerator Laboratory (FNAL) in Batavia, Illinois, uses a modular, high-energy sampling calorimeter as the basis of the detector system. This detector provides information on the energy and position of particles that exit a collision of a photon or pion with a target proton. While exiting particles are thought to form what are described as "jets", and several E683 projects involve working with these jets, it has not yet been demonstrated that jets indeed have been detected.The solution proposed here involves demonstrating that E683 data has a statistically significant "jettiness" even in a data sample which has not been biased. Towards this, a data sample was selected based on criteria unrelated to the presumption of jets. Planarity and the Et Flow were chosen as measures of how oblong(jetlike) an event is. The sample was then examined for planarity and Et flow in a number of kinematic ranges and the results demonstrate that over a certain kinematic range, events in our sample are increasingly planar, as we hypothesized. / Department of Physics and Astronomy

The subject of this thesis is the improvement of particle tracking through the identification and correction of small systematic errors in particle "hit" locations due to positioning of tracking detectors. These errors call be as large or larger than the statistical spatial resolution of tracking detectors themselves, and therefore must be corrected. The focus is on identification and correction of errors due to rotations and beam axis translations.An algorithm is developed for use with proportional wire chamber and drift chamber detectors in experiment E683 at the Wideband facility of Fermi National Laboratory. In this experiment, high energy (tens of GeV) particles, primarily mesons, were produced when photons with energies of 40-400 GeV struck a metal or liquid target.At the present time, the method and code developed for this thesis has not been applied to real data, although an analysis of its effectiveness as a function of detector resolution has been investigated with Monte-Carlo simulations. / Department of Physics and Astronomy

iThemba LABS is a particle accelerator facility housing a radionuclide production facility that uses a 66 MeV proton beam to produce radionuclides for medical and industrial use. Ionising radiation is produced by a variety of sources at Themba LABS. Ionising is a health hazard. High doses can cause acute radiation syndrome, i.e. "radiation sickness". Lower doses cannot cause acute symptom, but carry a risk of radiation-related cancer. Ionising radiation is also detrimental to materials, and can damage polymers and lubricants e.g. Shielding is used to reduce radiation levels to values that should be safe for the intended level of human occupancy. Shield performance is vital to human health and the life expectancy of polymers and lubricants, so that quality management in shield design is very important. However, until 2003, there has been no formal system at iThemba LABS to evaluate and improve all radiation shield designs and layouts from a radiation protection perspective. This study deals with evaluating and redesigning radiation shielding in the radionuclide production facility of iThemba LABS. There are several designs and layouts in the radionuclide production building of iThemba LABS that lead to unnecessary exposure of personnel to ionising radiation. The shielding in these areas are sub-standard. Performance criteria for radiation shields are developed. Inadequate radiation shields are identified. The identified inadequate shields are: the processing hotcells, the target store room and the hotcells in the radiopharmaceutical dispensing laboratory, Point-Kernel radiation shielding calculations are done to specify materials and material thickness that will adequately protect workers against ionising radiation. / Thesis (MSc. ARST) North-West University, Mafikeng Campus, 2004

Thesis (Ph.D.) -- McMaster University, 1998. / Includes bibliographical references (leaves 214-220). Also available via World Wide Web.