Caractérisation de l'indice de réfraction du radiateur aerogel du détecteur RICH de l'expérience LHCb

Characterisation of the refractive index of the aerogel raditor of RICH 1 detector of LHCb experiment. The purpose of this diploma work was to develop a reliable way to estimate the refractive index uniformity inside the aerogel radiator of the RICH 1 of LHCb. The constructor guarantees a variation of the refractive index within a single aerogel tile lower than 1%. Our measurements, performed on a full size prototype tile, show that this specification is met with a good margin. Our confidence in the overall performance of the detector in terms of single photon resolution and pion/kaon separation at low momenta is then justified. This thesis describes a new method for measuring the uniformity of n, called APACHE for Aerogel Photographic Analysis by Cherenkov Emission.