Projecto e implementação de uma fonte de alta tensão para produção de descargas eléctricas

O objetivo deste trabalho consistiu em projetar, construir e testar um protótipo em laboratório de uma fonte de alimentação de alta tensão que permita descargas elétricas {estáveis e de dimensões reduzidas}, de modo a que possa ser utilizada, dada a sua essencialidade, na fabricação de redes de período longo (LPG) em fibra ótica nos chamados turning points. Estes são pontos de elevada sensibilidade, fundamentais no desenvolvimento tecnológico de sensores em fibra ótica, em particular, de sensores refractométricos. O protótipo da fonte de alimentação é composto por um regulador do tipo BUCK, um inversor para alimentação do transformador de alta tensão, o circuito de realimentação e controlo PWM e um microcontrolador para o comando da fonte. Posteriormente procedeu-se à otimização dos parâmetros de descarga, o que conduziu a fabricação de redes de período longo com períodos inferiores a 150 micrómetros. Este é um resultado sem paralelo a nível internacional no que concerne ao uso da técnica do arco elétrico.

Fabrication and characterization of silicon position sensitive particle detectors

Position sensitive particle detectors are needed in high energy physics research. This thesis describes the development of fabrication processes and characterization techniques of silicon microstrip detectors used in the work for searching elementary particles in the European center for nuclear research, CERN. The detectors give an electrical signal along the particles trajectory after a collision in the particle accelerator. The trajectories give information about the nature of the particle in the struggle to reveal the structure of the matter and the universe. Detectors made of semiconductors have a better position resolution than conventional wire chamber detectors. Silicon semiconductor is overwhelmingly used as a detector material because of its cheapness and standard usage in integrated circuit industry. After a short spread sheet analysis of the basic building block of radiation detectors, the pn junction, the operation of a silicon radiation detector is discussed in general. The microstrip detector is then introduced and the detailed structure of a double-sided ac-coupled strip detector revealed. The fabrication aspects of strip detectors are discussedstarting from the process development and general principles ending up to the description of the double-sided ac-coupled strip detector process. Recombination and generation lifetime measurements in radiation detectors are discussed shortly. The results of electrical tests, ie. measuring the leakage currents and bias resistors, are displayed. The beam test setups and the results, the signal to noise ratio and the position accuracy, are then described. It was found out in earlier research that a heavy irradiation changes the properties of radiation detectors dramatically. A scanning electron microscope method was developed to measure the electric potential and field inside irradiated detectorsto see how a high radiation fluence changes them. The method and the most important results are discussed shortly.

27-8-20, circuit de la Sarthe, Isodi sur Douglas : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 60711

27-8-20, circuit de la Sarthe, motos Douglas (équipe) [Alexander, Isodi, Kickam] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 60713

27-8-20, circuit de la Sarthe, Kickam sur Douglas : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 60714

27-8-20, circuit de la Sarthe, Marc sur Thomann : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 60715

26-8-20, circuit de la Sarthe, H. Bartlett sur Verus : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 60716

27-8-20, circuit de la Sarthe, Dubost sur Motosolo I : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 60717

26-8-20, circuit de la Sarthe, Alexander sur Douglas : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 60718

27-8-20, circuit de la Sarthe, Vulliamy sur Alcyon : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 60719

26-8-20, circuit de la Sarthe, Borgotti sur A.B.C. : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 60720

26-8-20, circuit de la Sarthe, A. Milland sur Motosacoche : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 60721

26[-08-20] circuit de la Sarthe, A. Robert sur Motosacoche : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 60722

26-8-20, circuit de la Sarthe, Morel sur Blériot : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 60723

26-8-20, circuit de la Sarthe, Lavanchy sur Blériot : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 60724