Approved for public release; distribution is unlimited / A three dimensional analysis of the intensity distribution of backward optical transition radiation has been performed. The effects of variations in electron energy and beam divergence and on material properties such as dielectric permittivities and the resultant coherence length upon the angular distribution and polarization of optical transition radiation has been investigated. A surprising observation important to the use of optical transition radiation as a diagnostic tool for high energy electron beams is the behavior of the perpendicular component of the intensity. In contrast to low energies where the parallel component dominates, at electron energies above 200 MeV, the perpendicular component dominates. This requires the use of a polarization filter to diagnose particle beam properties at high energies. / http://archive.org/details/threedimensional00long / Lieutenant, United States Navy

Cette thèse est consacrée à l’étude des processus d’ondes au voisinage des chocs dans les plasmas spatiaux. La propagation des ondes de Langmuir dans un plasma présentant des inhomogénéités aléatoires de densité a été modélisée numériquement; les résultats obtenus ont été comparés aux données des instruments WHISPER et WBD à bord des satellites CLUSTER. Les résultats de modélisation et l’étude statistique portant sur l’intensité des ondes de Langmuir observées dans le préchoc terrestre et le vent solaire ont montré que le théorème central limite n’est pas applicable aux statistiques sur l’intensité, du fait du nombre insuffisant d’inhomogénéités. Il en résulte que la fonction de distribution de probabilité pour le logarithme des énergies d’ondes n’atteint pas la distribution normale. D’autre part la détection à distance de la zone quasi-perpendiculaire du front de choc terrestre a pu être effectuée en analysant la modulation des ondes de Langmuir et celle des ondes électrostatiques avec fréquence décalée à proximité de la limite du pré-choc. Il a été montré que la probabilité d’observation de la non-stationnarité du front de choc augmente avec le nombre de Mach du choc. Enfin le rayonnement de transition des électrons relativistes au front de choc quasi-perpendiculaire a été calculé pour expliquer le mécanisme de l’émission électromagnétique observée par les satellites près du front de choc interplanétaire le 22 janvier 2004. Les paramètres du calcul correspondent aux véritables paramètres de l’évènement. Le spectre du rayonnement de transition établi théoriquement a son maximum dans le même domaine de fréquence que pour les mesures. / The doctoral thesis is devoted to the investigation of wave processes in the vicinity of space plasma shocks. The numerical modelling of the Langmuir wave propagation in a plasma with random density inhomogeneities was performed and its results were compared with experimental data obtained by WHISPER and WBD instruments of the CLUSTER spacecraft project. The analysis results showed that the Central Limit Theorem is not applicable to the Langmuir wave intensity statistics in the Earth’s foreshock and the solar wind, because of insufficient number of inhomogeneities affecting the amplitude of the waves. Consequently the normal distribution of the probability distribution function for logarithm of wave energies is not achieved. The remote sensing of quasi-perpendicular part of the Earth’s bow shock front was performed using the analysis of the modulation of Langmuir, upshifted and downshifted wave intensities close to the foreshock boundary. The probability of the shock front nonstationarity observation was found to grow with shock Mach number. The transition radiation of the relativistic electrons at the interplanetary quasi-perpendicular shock front was calculated to explain the mechanism of electromagnetic emission observed by satellites near the shock front on January, 22, 2004. The parameters of the calculation corresponded to the actual parameters of the event. The theoretically predicted spectrum of transition radiation has its maximum in the same frequency region as in the measurements.

Since 2004, table-top laser-plasma accelerators (LPAs) driven by ˜30fs terwatt laser pulses have produced colimated, nearly mono-energetic eletron bunches with energy up to 1 GeV in laboratories around the world. Large-scale computer simulations show that LPAs can scale to higher energy while retaining high beam quality, but will require laser pulses of higher energy and longer duration than current LPAs. The group of Prof. Mike Downer, in collaboration with the Texas Petawatt (TPW) laser team headed by Prof. Todd Ditmire, is setting up an experiment that uses the TPW laser (1.1 PW, 150 fs) to drive the world’s first multi-GeV LPA. This thesis provides a general overview of the TPW-LPA project, including several diagnostic systems for the beam, plasma and laser pulse. Special attention is given to three of the diagnostic systems: (1)A transverse interferometry diagnostic of the plasma density profile created by the TPW laser pulse; (2)A Thomson scattering diagnostic of the self-guided path of the TPW laser pulse through the plasma; (3)An optical transition radiation diagnostic of the accelerated electron bunch exiting the plasma. In each case, basic principles, theoretical background, calculation and simulation results, and preliminary experimental results will be presented. / text

A megawatt class electron linear accelerator (e-linac) will be constructed at TRIUMF as part of the new ARIEL facility which will produce rare ion beams for the study of nuclear structure and astrophysics, and material science. The 50MeV, 10mA, continuous wave e-linac will drive gamma ray induced fissioning of a Uranium target for the production of neutron rich beam species. View Screens located at a number of places along the e-linac beam-line will acquire two dimensional images of the transverse electron beam profiles, providing measurements of the size, position, and shape of the incident e-linac beam. The design of the View Screens will be presented, based on design studies and simulations performed to evaluate the performance of the View Screens under various operating conditions. These studies include GEANT simulations of the energy loss and scattering of the electron beam as it passes through the scintillation and Optical Transition Radiation beam targets, the subsequent thermal response of the targets, and a ray tracing optics simulation to optimize the configuration of the imaging optics. Bench test have been performed on the resulting optics design to evaluate the imaging characteristics, verifying fulfillment of the design requirements. Construction of a prototype View Screen device is currently underway, with beam tests scheduled for Fall 2011. A total of 14 View Screens will be constructed and installed along the e-linac beam-line. / Graduate

No description available.

Este trabalho descreve o desenvolvimento de um simulador para as câmaras de expansão temporal / detectores de radiação de transição (TEC / TRD) do experimento PHENIX, instalado no Colisor de Íons Pesados Relativisticos (RHIC) do Laboratório Nacional de Brookhaven (BNL) nos EUA. O programa do RHIC prevê a produção e caracterização de um estado da matéria conhecido como plasma de quarks e glúons (QGP), através de colisões entre prótons, dêuterons e íons pesados com energias de centro de massa sqrt(s_NN) entre 20 e 200 GeV. O PHENIX, um dos quatro experimentos instalados no acelerador, é especializado na medida de sinais eletrofracos provenientes das colisões e o TEC / TRD é o único subsistema do PHENIX capaz de identificar elétrons de forma eficiente para momentos acima de 5 GeV/c. Um simulador para reprodução da resposta do detector à passagem de partículas foi desenvolvido e comparado a dados de um detector proporcional monofilar construído no Laboratório de Instrumentação e Partículas da USP, e aos dados do próprio TEC / TRD. Os resultados mostram um acordo razoável entre medidas e simulações. O uso do simulador deverá permitir o estudo de novos métodos e melhoras na capacidade de identificação de elétrons do sistema. / The present work describes the development of a simulator for the Time Expansion Chambers / Transition Radiation Detectors (TEC / TRD) of the PHENIX experiment, installed at the Relativistic Heavy Ion Collider (RHIC) of Brookhaven National Laboratory (BNL). The main goal of the RHIC project is the production and study of a state of matter known as Quark Gluon Plasma (QGP), through collisions of protons, deuterons and heavy ions at center of mass energies sqrt(s_NN) ranging between 20 and 200 GeV. PHENIX, one of the four experiments of the accelerator, is dedicated to measuring electroweak signals arising from the collisions, and TEC / TRD is the only subsystem capable of identifying efficiently electrons with momenta above 5 GeV/c. A simulator to reproduce the detector response to the passage of particles was developed and compared to data from a single wire proporcional counter and from TEC / TRD itself. The results show reasonable agreement between measurements and simulations. The use of the simulator allows studies of new methods and possibly improvements in the electron identification capability of the system.

Este trabalho descreve o desenvolvimento de um simulador para as câmaras de expansão temporal / detectores de radiação de transição (TEC / TRD) do experimento PHENIX, instalado no Colisor de Íons Pesados Relativisticos (RHIC) do Laboratório Nacional de Brookhaven (BNL) nos EUA. O programa do RHIC prevê a produção e caracterização de um estado da matéria conhecido como plasma de quarks e glúons (QGP), através de colisões entre prótons, dêuterons e íons pesados com energias de centro de massa sqrt(s_NN) entre 20 e 200 GeV. O PHENIX, um dos quatro experimentos instalados no acelerador, é especializado na medida de sinais eletrofracos provenientes das colisões e o TEC / TRD é o único subsistema do PHENIX capaz de identificar elétrons de forma eficiente para momentos acima de 5 GeV/c. Um simulador para reprodução da resposta do detector à passagem de partículas foi desenvolvido e comparado a dados de um detector proporcional monofilar construído no Laboratório de Instrumentação e Partículas da USP, e aos dados do próprio TEC / TRD. Os resultados mostram um acordo razoável entre medidas e simulações. O uso do simulador deverá permitir o estudo de novos métodos e melhoras na capacidade de identificação de elétrons do sistema. / The present work describes the development of a simulator for the Time Expansion Chambers / Transition Radiation Detectors (TEC / TRD) of the PHENIX experiment, installed at the Relativistic Heavy Ion Collider (RHIC) of Brookhaven National Laboratory (BNL). The main goal of the RHIC project is the production and study of a state of matter known as Quark Gluon Plasma (QGP), through collisions of protons, deuterons and heavy ions at center of mass energies sqrt(s_NN) ranging between 20 and 200 GeV. PHENIX, one of the four experiments of the accelerator, is dedicated to measuring electroweak signals arising from the collisions, and TEC / TRD is the only subsystem capable of identifying efficiently electrons with momenta above 5 GeV/c. A simulator to reproduce the detector response to the passage of particles was developed and compared to data from a single wire proporcional counter and from TEC / TRD itself. The results show reasonable agreement between measurements and simulations. The use of the simulator allows studies of new methods and possibly improvements in the electron identification capability of the system.

In laser wakefield acceleration, an ultra-short high-intensity laser pulse excites a plasma wave, which can sustain accelerating electric fields of several hundred GV/m. This scheme advances a novel concept for compact and less expensive electron accelerators, which can be hosted in a typical university size laboratory. Furthermore, laser wakefield accelerators (LWFA) feature unique electron bunch characteristics, namely micrometer size with duration ranging from several fs to tens of fs. Precise knowledge of the longitudinal profile of such ultra-short electron bunches is essential for the design of future table-top X-ray light-sources and remains a big challenge due to the resolution limit of existing diagnostic techniques. Spectral measurement of broadband coherent and incoherent transition radiation (TR) produced when electron bunches passing through a metal foil is a promising way to analyze longitudinal characteristics of these bunches. Due to the limited reproducibility of the electron source this measurement highly requires single-shot capability. An ultra-broadband spectrometer combines the TR spectrum in UV/NIR (200-1000 nm), NIR (0.9-1.7 µm) and mid-IR (1.6-12 µm). A high spectral sensitivity, dynamic bandwidth and spectral resolution are realized by three optimized dispersion and detection systems integrated into a single-shot spectrometer. A complete characterization and calibration of the spectrometer have been done concerning wavelengths, relative spectral sensitivities, and absolute photometric sensitivities, also taking into account for the light polarization. The TR spectrometer is able to characterize electron bunches with charges as low as 1pC and can resolve time-scales of 0.4 fs. Electron bunches up to 16 fs (rms width) can be reconstructed from their TR spectrum. In the presented work, the self-truncated ionization induced injection (STII) scheme has been explored to study the relevant beam parameters especially its longitudinal bunch profile and the resulting peak current.