Cosmic rays are at the foundation of astroparticle physics and the extensive air showers (EAS) is one indirect way to detect them. Air showers, however, have been used to infer information not just of cosmic rays particles, but also to localize gamma rays sources. The shower maximum of an EAS, defined as the position at the atmosphere where the maximum quantity of charged particles is reached, is an observable of air showers that can permit to infer the mass composition of cosmic rays. For this reason, it is important to propose methods to measure it. Several methods to determine the shower maximum have been implemented in the last decades with the development of different kinds of telescopes. This work discusses the possibility of determining the maximum of air showers using imaging atmospheric Cherenkov telescopes (IACT). The Cherenkov telescopes can detect the Cherenkov radiation produced by the interaction of charged particles with the atmosphere. Those Cherenkov photons are projected back into the plane containing the longitudinal development of the air shower. Each plane is saved as a 2D histogram with the longitudinal and lateral development in the vertical and horizontal axis, respectively. A detailed analysis of each 2D histogram is presented and used to obtain the depth of the maximum of the Cherenkov profile. The main effect seen is a decrease in the shower maximum of Cherenkov photons as a function of the telescope position from the shower axis to 150 m. After 150m from the shower axis, there is a constant behavior that is correlated to the real depth of the maximum of an EAS. Based on this constant behavior after 150 m, the shower maximum is reconstructed and it is shown the resolution of the method as a function of the energy, which is around 55 g/cm2 considering just one telescope, and 15 g/cm2 for the best case considering zenith angle of 20 degrees. Moreover, the method is tested with some simulations took from Very Energetic Radiation Imaging Telescope Array System (VERITAS) experiment to compare with the results of our simulations. The resolution of the reconstruction of the shower maximum for proton and iron showers was also done which ranges around 80 g/cm2 for proton and around 30 g/cm2 for iron in the case of 20° of zenith angle. / Os raios cósmicos estão na base da física das astropartículas e os chuveiros atmosféricos extensos (EAS pela sigla em inglês) são uma maneira indireta de detectá-los. Os chuveiros atmosféricos, no entanto, têm sido usados para inferir informações não apenas sobre partículas de raios cósmicos, mas também para localizar fontes de raios gama. A profundidade de máximo num EAS, definido como a profundidade atmosférica onde a quantidade máxima de partículas carregadas é atingida, é um observável de EAS que permite inferir a composição de massa dos raios cósmicos. Por esse motivo, é importante propor métodos para medí-lo. Vários métodos para determinar a profundidade de máximo foram implementados nas últimas décadas com o desenvolvimento de diferentes tipos de telescópios. Este trabalho discute a possibilidade de determinar a profundidade de máximo de chuveiros atmosféricos utilizando os telescópios atmosféricos Cherenkov (IACT). Os telescópios Cherenkov podem detectar a radiação Cherenkov produzida pela interação de partículas carregadas com a atmosfera. Esses fótons Cherenkov são projetados de volta ao plano que contém o desenvolvimento longitudinal do chuveiro. Cada plano é salvo num histograma 2D com o desenvolvimento longitudinal e lateral no eixo vertical e horizontal, respectivamente. Uma análise detalhada de cada histograma 2D é apresentada e usada para obter a profundidade máxima do perfil de emissão de luz Cherenkov. O principal efeito visto é uma diminuição na profundidade de máximo dos fótons Cherenkov do chuveiro como função da posição do telescópio a partir do eixo do chuveiro até 150 m. A partir de 150 m do eixo do chuveiro, há um comportamento constante que está correlacionado com a profundidade real de máximo do EAS. Com base nesse comportamento constante após 150 m, o máximo do chuveiro é reconstruído e é mostrada a resolução do método em função da energia, que é cerca de 55 g/cm2 considerando apenas um telescópio, e 15 g/cm2 para o melhor caso, considerando o ângulo zenital de 20 graus. Além disso, o método é testado com algumas simulações cedidas pelo experimento VERITAS (Very Energetic Radiation Imaging Telescope Array System, pela sigla em inglês) para comparar com os resultados de nossas simulações. Também foi feita a resolução da reconstrução da profundidade de máximo para chuveiros atmosféricos de prótons e ferro, que varia em torno de 80 g/cm2 para prótons e em torno de 30 g/cm2 para ferro no caso chuveiros inclinados a um ângulo de 20°.

Dark matter (DM), whose nature and interaction mechanisms are still an open issue, constitutes about 25 % of the Universe energy density. Weakly Interacting Massive Particles (WIMPs) are considered as strong candidates for particle DM and their search is conveniently carried out through the detection of gamma rays. The newly discovered ultra-faint dwarf spheroidal galaxies (dSphs), located in the vicinity of the Galaxy, exhibit high values of the mass to luminosity ratio, and are therefore considered as strongly dominated by DM. These objects are within reach of the Cherenkov Telescope Array (CTA), which is the future project for gamma-ray astronomy, with an better sensitivity (one order of magnitude) with respect to the current generation experiments. The main goal of the present work is the study of the sensitivity of CTA to WIMPs DM particles, by simulating the observation of the ultra-faint dwarf spherical galaxies Triangulum II, Reticulum II and Carina III, as well as of the classical dwarf galaxy Sculptor, for different annihilation channels, between 70 GeV and 100 TeV. The sensitivity curve in the WIMPs parameter space (velocity-averaged annihilation cross section < &sigma; &nu; > and DM mass mDM) was computed. We found that, within the sample of dwarf galaxies tested, Triangulum II is the most promising source, able to reach the thermal freeze-out values in the annihilation channel &tau;+&tau;- for only 50 hours of observation. Our result, the first estimation of the sensitivity for DM searches in ultra-faint dwarfs with CTA, is consistent with results from current generation experiments, showing better performance over an extended energy range. The limited sample of available stars in the targets induces uncertainties on the DM content. Future measurements, leading to a better understanding of the sources dynamic equilibrium, can improve this situation. Even so, the combination of the high DM content in the ultra-faint dwarf galaxies, together with the excellent expected performance of the future CTA, provides a promising result for indirect DM searches. / A matéria escura, cuja natureza e mecanismos de interação ainda estão em aberto, compõe 25% da densidade de energia do Universo. Weakly Interacting Massive Particles (WIMPs) apresentam-se como forte candidatas e sua busca é convenientemente conduzida através de raios gama. As recém descobertas galáxias esferoidais anãs ultra-fracas, situadas nos arredores da Galáxia, apresentam altos valores da razão entre massa e luminosidade, sendo portanto consideradas objetos fortemente dominados por matéria escura. Esses objetos estão ao alcance do Cherenkov Telescope Array (CTA), que é o futuro projeto da astronomia gama, com sensibilidade de uma order de grandeza melhor do que os experimentos atuais. O presente trabalho teve como objetivo estudar o potencial de detecção indireta de WIMPs através de raios gama com o futuro observatório CTA, observando as galáxias esferoidais anãs ultra-fracas Triangulum II, Retículum II e Carina III e a galáxia anã clássica Sculptor, para diferentes canais de aniquilação, entre 70 GeV e 100 TeV. A curva de sensibilidade no espaço de parâmetros livres de WIMPs (massa da partícula mDM e médida da seção de choque de aniquilação ponderada pela velocidade < &sigma; &nu; >) foi calculada. Nós encontramos que dentro da amostra de galáxias anãs testadas, Triangulum II é a fonte mais promissora, capaz de testar os valores térmicos no canal de aniquilação &tau;+&tau;- considerando apenas 50 horas de observação pelo CTA. Nosso resultado, a primeira estimativa da sensibilidade para busca de matéria escura em galáxias esferoidais anãs ultra-fracas com CTA, é consistente com resultados de experimentos da geração atual, e mostra um melhor desempenho em uma faixa de energia estendida. Os resultados são afetados pelas incertezas devido à pequena amostra de estrelas dos alvos escolhidos, que se reflete no conhecimento do conteúdo de matéria escura. Novas medidas podem ajudar a esclarecer essa situação. Ainda assim, a combinação de galáxias anãs ultra-fracas, aliada às melhorias do futuro CTA, apresenta-se como um passo muito promissor para buscas indiretas de matéria escura.

In this thesis I describe the development of a compact camera for ground-based multi TeV gamma-ray astronomy, using the Imaging Atmospheric Cherenkov Telescope (IACT) technique. The camera is based on multi-anode photomultipliers (MAPM) and is designed for use on the Gamma Cherenkov Telescope (GCT), which is proposed to be part of the Small Size Telescope (SST) array of the Cherenkov Telescope Array (CTA). GCT achieves high performance with a compact and cost efficient design via a Schwarzschild-Couder (SC) dual-mirror optical system. The GCT optical design allows the use of a compact camera of diameter roughly 0.5 m. The curved focal plane is equipped with 32 tiles of 64-pixels MAPM for a total of 2048 pixels of ~0.2° angular size, resulting in a field of view of ~9°. The GCT camera is designed to record the flashes of Cherenkov light from electromagnetic cascades, which last only a few tens of nanoseconds. I give a detailed description of the design, the challenges encountered during testing in the lab, and the performance of the most critical components. I give details on the custom front-end electronics modules that provide the required fast electronics, facilitating sampling and digitization, as well as first level of triggering. The camera-level triggering system is a custom backplane, developed to reject spurious triggers on the night sky background, which typically is of the order of few tens of millions of photons per pixel per second. This is to be compared with the rate of the astrophysical signal, which is of the order of few hundreds of events per second at the relevant energies. Additionally I provide a detailed description of all the software needed for the data acquisition and control of the camera, from the very low level drivers to high level and user friendly processes. I follow the commissioning of the camera, from the individual core components to the integration of the system. I then describe the integration of the camera on the GCT prototype telescope structure, and the achievement of "first light", validating for the first time the full proof-of-concept of an IACT with SC optics. I also report a study I performed on expectations for an extragalactic survey for blazars with CTA. The cumulative source count distribution of blazars is presented, including implications from two different phenomena: axion-like particle (ALP) to gamma-ray oscillations in the intergalactic magnetic field, and secondary gamma rays from hadronic origins. I conclude that a shallow and wide survey will provide the best science return for CTA, that the impact of ALP is modest and that the secondary mechanism of gamma-ray production would allow detection of blazars up to redshift of 1 in the multi-TeV energy band.

No description available.

No description available.

LHCb is a high-precision experiment for the study of CP violation and rare decays in B physics. It has two Ring Imaging Cherenkov (RICH) counters for particle identification. The RICH system uses Hybrid Photon Detectors (HPD) for single photon detection. This thesis describes tests performed on individual HPDs for quantum efficiency and vacuum quality. It then presents work done monitoring HPD vacuum quality through regular ion feedback measurements after they were mounted into the RICH. Also discussed is HPD vacuum degradation and how replacement and repair of deteriorated HPDs was implemented using data from the vacuum monitoring. Preparations for an upgrade to LHCb have started. The upgrade will extend the discovery potential of the LHCb by increasing the rate of data collection. This thesis presents particle identification and avour tagging studies using upgrade simulations. Flavour tagging using kaons was then reoptimised for upgrade conditions and this work is described with discussions of the results.

by Lui Bong Chun, Richard. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references. / Abstract / Acknowledgment / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Background for the Project --- p.1 / Chapter 1.1.1 --- Interests in Blue-Green Laser --- p.1 / Chapter 1.1.2 --- Progress of Blue-Green Laser --- p.2 / Chapter 1.2 --- The Aim of the Project --- p.3 / Chapter 1.3 --- Overview the Remaining Parts of this Thesis --- p.4 / Chapter 1.4 --- References --- p.6 / Chapter Chapter 2 --- Sum Frequency Generation --- p.8 / Chapter 2.1 --- Introduction --- p.8 / Chapter 2.2 --- Sum Frequency Generation --- p.8 / Chapter 2.2.1 --- Theoretical Background for Sum Frequency Generation --- p.9 / Chapter 2.2.2 --- The Coupled Wave Equations for SFG --- p.13 / Chapter 2.2.3 --- Phase Matching Considerations --- p.16 / Chapter 2.3 --- References --- p.18 / Chapter Chapter 3 --- Cerenkov Radiation --- p.19 / Chapter 3.1 --- Introduction --- p.19 / Chapter 3.2 --- The Properties of Cerenkov Radiation by Using TM Mode --- p.21 / Chapter 3.2.1 --- Refractive Index Notation --- p.23 / Chapter 3.2.2 --- Fundamental Wave TM Guides Mode --- p.23 / Chapter 3.2.3 --- Second Harmonic TM Radiation Mode --- p.24 / Chapter 3.2.4 --- Efficiency of SHG --- p.25 / Chapter 3.3 --- Simplified Model Analysis of Cerenkov Radiation in TE Mode --- p.29 / Chapter 3.4 --- Simulation --- p.33 / Chapter 3.4.1 --- Modeling the LiNb03 --- p.33 / Chapter 3.4.2 --- Modeling an Asymmetric Slab Waveguide ´ؤPMMA doped with MNA on Fused Quartz --- p.37 / Chapter 3.4.3 --- Modeling a Symmetric Slab Waveguide ´ؤPMMA doped with MNA on Fused Quartz --- p.42 / Chapter 3.5 --- References --- p.47 / Chapter Chapter 4 --- Ellipsometry --- p.49 / Chapter 4.1 --- Introduction --- p.49 / Chapter 4.2 --- General Principles --- p.49 / Chapter 4.3 --- Basic Operation --- p.50 / Chapter 4.4 --- The Optical Constants of the Bulk Materials --- p.51 / Chapter 4.5 --- Calculation the Refractive Index of the Substrates --- p.53 / Chapter 4.6 --- Ellipsometric Theory for the Thin Film --- p.57 / Chapter 4.7 --- Measurement the Refractive Index and the Thickness of the Thin Film --- p.59 / Chapter 4.7.1 --- Data --- p.62 / Chapter 4.7.2 --- Discussions --- p.73 / Chapter 4.8 --- Calculation the Refractive Index of the thin Film by Considering as a Bulk Material --- p.78 / Chapter 4.9 --- References --- p.80 / Chapter Chapter 5 --- Prism Coupling --- p.81 / Chapter 5.1 --- Introduction --- p.81 / Chapter 5.2 --- Coupling of a Plane Wave --- p.82 / Chapter 5.3 --- Numerical Approach for the Calculation of the Coupling Efficiency --- p.85 / Chapter 5.4 --- Experiment --- p.88 / Chapter 5.4.1 --- Experimental Setup --- p.88 / Chapter 5.4.2 --- Experimental Result and Discussions --- p.90 / Chapter 5.5 --- References --- p.92 / Chapter Chapter 6 --- Conclusion --- p.93 / Chapter Chapter 7 --- Future Plans --- p.96 / Chapter 7.1 --- Simplified Model of Corona Poling --- p.96 / Chapter 7.2 --- Advanced Models of Poling --- p.98 / Chapter 7.2.1 --- Slab Waveguide --- p.98 / Chapter 7.2.2 --- Channel Waveguide --- p.99 / Chapter 7.3 --- References --- p.100 / Chapter Appendix 1 --- Materials' Descriptions --- p.A-l / Chapter A.1.1 --- 2-Methyl-4-Nitoaniline --- p.A-1 / Chapter A.1.2 --- Poly ( Methyl Methacrylate ) --- p.A-3 / Chapter A.1.3 --- References --- p.A-4 / Chapter Appendix 2 --- Fabrication Procedures --- p.A-5 / Chapter A.2.1 --- Cleaning the Apparatus --- p.A-5 / Chapter A.2.2 --- Cleaning the Substrate --- p.A-5 / Chapter A.2.3 --- Thin film Fabrication --- p.A-5 / Chapter A.2.4 --- Thin Film Removal --- p.A-6 / Chapter A.2.5 --- References --- p.A-6 / Chapter Appendix 3 --- Alpha Step --- p.A-7 / Chapter A.3.1 --- Introduction --- p.A-7 / Chapter A.3.2 --- Experimental Setup --- p.A-8 / Chapter A.3.3 --- Experimental Results --- p.A-9 / Chapter A.3.3.1 --- Thin Film of PMMA without Dopant --- p.A-9 / Chapter A.3.3.2 --- Thin Film of PMMA doped with MNA --- p.A-19 / Chapter A.3.4 --- Discussions --- p.A-27 / Chapter A.3.5 --- References --- p.A-28 / Chapter Appendix 4 --- Scanning Electron Microscope --- p.A-29 / Chapter A.4.1 --- Scanning Electron Microscope --- p.A-29 / Chapter A.4.2 --- Reference --- p.A-30 / Chapter Appendix 5 --- Gaussian Beam & Coordinate System Transformation --- p.A-31 / Chapter A.5.1 --- Gaussian Beam in a Homogeneous Medium --- p.A-31 / Chapter A.5.2 --- Transformation of the Coordinate Systems --- p.A-32 / Chapter A.5.3 --- Reference --- p.A-32 / Chapter Appendix 6 --- Waist Size Measurement of Gaussian Beam --- p.A-33 / Chapter A.6.1 --- Waist Size Measurement of Gaussian Beam --- p.A-33 / Chapter A.6.2 --- References --- p.A-34 / Chapter Appendix 7 --- Quasi Phase Matching --- p.A-35 / Chapter A. 7.1 --- Introduction --- p.A-35 / Chapter A.7.2 --- Basic Concept of QPM --- p.A-36 / Chapter A.7.3 --- References --- p.A-38 / Chapter Appendix 8 --- Program Listing --- p.A-41 / Chapter A.8.1 --- Program Listing ( Chapter 3 ) --- p.A-41 / Chapter A.8.1.1 --- Program 3.1 (transcendental.m ) --- p.A-41 / Chapter A.8.1.2 --- Program 3.2 (linbo3.m) --- p.A-42 / Chapter A.8.2 --- Program Listing ( Chapter 4 ) --- p.A-45 / Chapter A.8.2.1 --- Program 4.1 ( ellipsometry.m ) --- p.A-45 / Chapter A.8.3 --- Program Listing ( Chapter 5 ) --- p.A-47 / Chapter A.8.3.1 --- Program 5.1 ( parameter.m ) --- p.A-47 / Chapter A.8.3.2 --- Program 5.2 ( coupling.m ) --- p.A-49 / Chapter A.8.3.3 --- Program 5.3 ( v_3_amp.m ) --- p.A-50 / Chapter A.8.3.4 --- Program 5.4 ( input_profile.m ) --- p.A-51

L'experience spatiale AMS sera mise en orbite à partir de 2008 pour une durée de 3 ans afin d'étudier le rayonnement cosmique, l'antimatière et la matière noire. Cette thèse présente d'abord le travail mené pour les developpements de l'imageur Cherenkov (RICH) d'AMS qui conduira à une mesure précise de la vitesse et de la charge des particules. Nous exposons les caractéristiques générales de l'imageur, ainsi que la mise en oeuvre et l'analyse des données provenant de tests sur faisceau d'ions realisés au CERN. Nous présentons également les test de l'électronique frontale, l'analyse et le tri des composants les mieux adaptés à l'expérience. Une méthode d'étalonnage et de reclassement des cellules de l'imageur a été proposée et acceptée par la collaboration. Finalement, nous avons developpé un banc de test afin de déterminer l'indice de refraction des aérogels (utilisés comme matériau radiateur).

<p>The world’s largest particle accelerator, Large Hadron Collider, located at CERN outside Geneva performed its first proton-proton collisions in November 2009. One of the four main experiments is LHCb, studying rare decays of hadrons containing the beauty quark. An essential part of the particle identification in LHCb is made by the two Ring Imaging Cherenkov detectors. These detectors use pixel Hybrid Photon Detectors for detection and imaging of Cherenkov rings. This paper reports on measurements carried out on the Hybrid Photon Detectors, including a discussion of the results. In particular, ageing effect and image stability are studied. A fraction of the photon detectors show a degradation in performance within these fields.</p> / <p>Världens största partikelaccelerator, LHC, belägen vid CERN utanför Genève utförde sina första proton-proton kollisioner i November 2009. Ett av de fyra huvudexperimenten är LHCb, som studerar sällsynta sönderfall av hadroner innehållande <em>b</em> kvarken. En viktig del av partikelidentifikationen i LHCb görs av de två RICH detektorerna. Dessa använder hybrida fotondetektorer för detektering och avbildning av Cherenkov ringar. Denna rapport handlar om mätningar utförda på dessa hybrida fotondetektorer, med en diskussion av resultaten. I synnerhet studeras åldringseffekter och bildstabilitet. En andel av fotondetektorerna visar en degradering i prestanda inom dessa områden.</p>

La historia de la astronomía de los rayos gammas en los últimos veinte años está marcada por el éxito que los telescopios Cherenkov han tenido en la exploración de la banda de muy altas energías. La ultima generación de telescopios Cherenkov, que incluye los telescopios HESS, VERITAS y MAGIC, ha logrado, en sólo siete años, aumentar el número total de fuentes conocidas de muy altas energías, desde unas pocas hasta más de un centenar. Esta populación de fuentes incluye objetos galácticos y extragalácticos. Los telescopios Cherenkov se han demostrado muy eficientes en el descubrimiento de nuevas emisoras de rayos gammas y también en el estudio detallado de la propiedades físicas de las fuentes bien conocidas, como por ejemplo, la Nebulosa del Cangrejo, el prototipo de los pleriones o Nebulosas de Viento de Púlsar ("pulsar wind nebulae"). Gracias a su brillo a todas las longitudes de onda, el Cangrejo es una fuente astrofísica de referencia. Su espectro ha sido medido en veinte ordenes de magnitud en energía, desde las frecuencias radio hasta las muy altas energías, pero nuevas medidas resultan aún esenciales para entender las contradicciones que surgen cuando se combinan los resultados de diferentes longitudes de onda. Finalizado del commissioning del segundo telescopio en el Otoño del 2009, y tras el comienzo de la toma de datos en modalidad estereoscopica, MAGIC ha mejorado significantivamente su rendimiento y alcanza el umbral en energía más bajo de todos los telescopios Cherenkov. Por lo tanto MAGIC es un instrumento ideal para medir el espectro de la Nebulosa del Cangrejo con una precisión sin precedentes a partir de 50 GeV. Este logro tiene una importancia extraordinaria para el astrofísica de muy altas energías y tiene el potencial de solucionar unos de los misterios aun no resueltos de esta fuente. Este es uno de los asuntos centrales de este trabajo de tesis. Por otro lado, MAGIC ha tenido también un impacto fundamental en el descubrimiento de nuevos objetos astrofísicos, y, con la mejora en sensibilidad del nuevo sistema de dos telescopios , este impacto será aún mas significativo. Entre las fuentes galacticas, los microcuásares constituyen unos de los mejores candidatos a emisores de rayos gammas. Su caracterización a muy alta energía aportaría información muy útil para entender la formación de chorros de partículas en objetos astronomicos. Aunque muchos modelos teóricos predicen esta emisión, aún no ha sido detectada. De hecho hay evidencias de que los tres sistemas binarios que se han detectado hasta la fecha por encima de 300 GeV son binarias de púlsares más que microcuásares. Sin embargo, el hecho que el microcuásar Cygnus X-3 haya sido detectado por encima de 100 MeV por los satélites AGILE y Fermi/LAT confirma que esta clase de objetos sigue siendo un objetivo interesente por la astrofísica de muy alta energía. En los últimos años, MAGIC ha dedicado un esfuerzo muy importante búsqueda de señales desde los microcuásares. Esta tesis presenta los resultados de las observaciones de dos de ellos: Cygnus X-3 y Scorpius X-1. Se han logrado extraer los limites superiores al flujo integral de estas dos fuentes más restrictivos hasta la fecha por encima de unos centenares de GeV. Para Cygnus X-3 en particular, se presentan además las primeras observaciones a estas energías totalmente simultáneas con la emisión detectada por los satélites. / of the Imaging Atmospheric Cherenkov Telescopes (IACTs) in the exploration of the Very- High-Energy (VHE) band. The last generation of IACTs have been capable to increase the total number of known VHE emitting sources from a few to almost one hundred in just seven years of operation. This population comprises galactic and extragalactic objects. IACTs have proved to be very effective in both the discovery of new emitters, as well as in the fine analysis of the physics properties of well established sources. Among them, the Crab Pulsar Wind Nebula is probably the best studied astrophysical object and the archetypal PWN. Due to its brightness at almost all wavelenghts, it is considered as an astrophysical candle. Despite the Crab Nebula broad-band spectrum has been thoroughly studied across twenty orders of magnitudes, from radio frequencies to VHE, further effort is needed to resolve the contradictions in the combination of all the multiwavelenght results. With the commissioning of the second MAGIC telescope in 2009 and the beginning of the operations in stereoscopic mode, the performance of the instrument improved dramatically, allowing MAGIC to reach the lowest ever energy threshold among all the existing IACTs, and describe the Crab Nebula spectrum with unprecedented precision down to 50 GeV. This achievement is of crucial importance for the VHE !-ray astrophysics in the pre-CTA era, since it can cast new light on some of the unsolved mysteries of one of its most established sources. On the other hand, MAGIC made a strong impact in the discovery of new VHE sources and, with the improved sensitivity of the stereoscopic mode, this will be even more so in the future. Among the galactic objects, Microquasars (MQs) constitute some of the best candidates for VHE emission, but despite several well accepted models predict such signal, it has not been detected. There are, in fact, evidences that the three binary systems which have been unambiguously detected at energies above few hundreds of GeV are binary pulsars rather than accreting microquasars. Nevertheless, the recent detection of the microquasar Cygnus X-3 above 100 MeV by both Agile and Fermi satellites, and the claim of short oneday flares from Cygnus X-1 reported by Agile confirmed that microquasars remain interesting targets for VHE telescopes. MAGIC made a strong effort in searching for VHE signals from microquasars, but found only a non-significant evidence of signal from Cygnus X-1 in 80 minutes of observation on September 24, 2006. MAGIC tried to detect similar flares in the following four years but the subsequent hundred more hours of observations were unsuccessful. Besides Cygnus X-1, MAGIC pointed at two other microquasar candidates, whose results are presented in this thesis: Cygnus X-3 and Scorpius X-1. The most constraining UL to the integral flux of these sources at the energy above few hundred GeV are provided. Further investigations are being planned to discover these sources at VHE in the next years.