Etude de la mesure des emittances transverses d'un faisceau par la methode des gradients. Application au cas d'une focalisation par solenoide

Within the framework of the ALTO project (Linear Accelerator near the Orsay Tandem), IPNO will recover the LAL station NEPAL, which will be used as the ALTO injecting system. To calculate the beam optics through the linear accelerator, it is necessary to determine the electron beam emittance at the exit of the buncher station. There are several methods to determine this emittance: direct methods, like the Pepper Pot technique, and indirect ones, like the three distances method and the three gradients one. The latter requires a variable optic element (quadrupole, solenoid...). In the case of the use of a solenoid, the horizontal and vertical motions are coupled, which implies an additional difficulty for the analysis of the measurements. The main goal of this report is to identify and to solve these mathematical difficulties, so as to determine at last the initial emittance. The treated example comes from a paper by R.Chehab et al [12], the code used is BETA, and resolution is done using the last square method. The remarks and the results obtaoined will be used for the measurements of the NEPAL emittance value at the LAL

Utilisation de faisceaux d'électrons pour la production des noyaux radioactifs par photo-fission

Le thème central de cette thèse est l'étude de la faisceaulogie de l'accélérateur ALTO et des lignes de transport associées. La première partie présente l'étude effectuée sur l'injecteur. Les simulations faites à l'aide du code de calcul PARMELA, ont permis l'optimisation des caractéristiques du pré-groupeur afin d'obtenir un bon groupement à l'entrée du groupeur et á l'entrée de la section accélératrice en fonction de la distance qui les sépare. La deuxiéme partie de cette thèse a porté sur les mesures de l'émittance transverse du faisceau à la sortie du groupeur. La méthode choisie est celle de trois gradients et le système optique utilisé est un solénoide. Les résultats obtenus s'avèrent en bon accord avec des mesures antérieures. Enfin un calcul de la ligne optique a été réalisé afin d'optimiser le transport du faisceau jusqu'à la cible PARRNe sans dégrader ses caractéristiques. Les codes de calcul utilisés sont BETA et TRACE-WIN.NI

Utilisation de faisceaux d'électrons pour la production des noyaux radioactifs par photo-fission

L'IPN d'Orsay a décidé de construire un accélérateur linéaire d'électrons afin de produire un faisceau d'électrons d'énergie de 50 MeV et d'intensité moyenne de 0.01 mA. C'est le projet ALTO (Accélérateur Linéaire auprès de Tandem d'Orsay). Ce projet sera dédié à la production des noyaux radioactifs par photo-fission. Le thème central de cette thèse est l'étude de la faisceaulogie de cet accélérateur et des lignes de transport associées. La première partie présente l'étude effectuée sur l'injecteur. Les simulations faites à l'aide du code de calcul PARMELA, ont permis l'optimisation des caractéristiques du pré-groupeur (déphasage HF, champ crête accélérateur,.) afin d'obtenir un bon groupement à l'entrée du groupeur et à l'entrée de la section accélératrice en fonction de la distance que les sépare. La deuxième partie de cette thèse a porté sur les mesures de l'émittance transverse du faisceau à la sortie du groupeur. La méthode choisie est celle de trois gradients et le système optique utilisé est un solénoïde. Les résultats obtenus s'avèrent en bon accord avec des mesures antérieures. Enfin un calcul de la ligne optique a été réalisé afin d'optimiser le transport du faisceau jusqu'à la cible PARRNe sans dégrader ses caractéristiques. Les codes de calcul utilisés sont BETA et TRACE-WIN.The IPN of Orsay decided to build a linear accelerator in order to produce an electron beam of 50 MeV energy and of 0.01 mA average intensity. It is the ALTO project (Linear Accelerator near the Tandem of Orsay). This project will be dedicated to the production of the radioactive ions using the photo-fission process. The central topic of this thesis is the study of the beam dynamics of the ALTO facility. The first part presents studies concerning the injector. The simulations made with the simulation code PARMELA allowed the optimization of the characteristics of pre-buncher (dephasing HF, accelerating field peak..) to obtain a good bunching factor at the entrance of the buncher and at the entrance of the accelerating section according to the distance separating the two systems. The second part of this thesis is related to measurements of transverse emittance of the beam at the buncher exit. The three gradients method has been selected and the optical system used is a solenoid. The results obtained are in good agreement with former measurements. Finally a calculation of the beam line was carried out to optimize the transport of the beam to the PARRNe target without degrading its characteristics. The calculation codes that have been used are BETA and TRACE-WIN.STRASBOURG-Bib.Central Recherche (674822133) / SudocORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Study of superconducting RF 3 GHz cavities realized by spinning

In the context of an R&D program aiming at developing new fabrication techniques, three bulk Niobium 3 GHz seamless SRF cavities were produced by spinning at INFN Legnaro. These prototype cavities for different nominal thicknesses were tested at IPN Orsay in the temperature range 1.7–4.2 K. In the course of the experiments, several parameters were investigated: surface resistance R s vs. temperature T, magnetic penetration depth as function of T and Lorentz forces detuning factor K. Electromagnetic simulations were also performed. The results obtained are reported and discussed. The characteristics Q 0 vs. E acc of the three cavities showed field emission and the RF tests were limited by the power available. Moreover, the energy gap was deduced from the R s vs. T results and compared to data previously reported on niobium leading to a good agreement. Finally, these cavities seem to be more sensitive (i.e. higher detuning factor) to Lorentz forces detuning compared to cavities of same geometry produced by deep drawing and electron beam welding

Retinal Emboli in Cholesterol Crystal Embolism

Cholesterol crystal embolism (CCE) is a rare and severe multisystemic disorder. It results from a massive release of cholesterol crystals from widespread atherosclerotic disease. The main difference with atherosclerosis is the severity and the quantity of the embolic events that occur during the course of the disease, eventually leading to multivisceral failure and death. The symptoms are multiple and make it a diagnostic challenge. Fundoscopic examination can be of great help, showing retinal emboli in up to 25% of the cases, and has been rarely described in the ophthalmologic literature. We report the case of a 77-year-old man with acute renal failure after coronarography. Retinal emboli seen in the fundus confirmed the diagnosis of cholesterol crystal embolism and thus prevented any further invasive investigations. In this case, anticoagulants must be stopped and any further endovascular procedure proscribed. Although impossible for this patient, peritoneal dialysis should be preferred to hemodialysis because it does not need any anticoagulation. Systemic corticosteroid can be used in the acute phase. Fundoscopic examination should be performed each time cholesterol crystal embolism is suspected. When typical emboli are seen in the retina, it permits avoiding invasive investigations and saving precious time for the management of this potentially lethal disease

The ALTO project: a 50 MeV electron beam at IPN Orsay

ACC SPR NI

Recurrent herpetic keratitis despite antiviral prophylaxis: A virological and pharmacological study

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