Triangulation - trilateration relatives a l'installation du synchrotron a protons souterrain (SPS) au CERN a Geneve

Since 1954, several particule accelerators were realized by the European Organization for Nuclear Research (CERN). These machines allow to accelerate the particules, which, after a certain number of rotations, strike on targets. To obtain best results, it is necessary to increase the energy of the particules. This is the aim pf the 300 GeV Underground Proton Synchrotron, which will be put in service in 1976. The SPS is located in a 7.0 km long tunnel. One of the two experimental areas uses a preexistant hall; the other is laid out in the North part of the site. Up to date, the various stages of the SPS construction required several successive extensions of the geodetic network. Actually, the boring of the tunnel is finished, the installation of the magnets is in progress as the first works in the North Experimental Areas. The geodetic network, composed of some fifteen points, has been carried out by means of triangulation and trilateration. It must be set up so as to allow the geometrical link between the surface and the tunnel and the creation of a certain number of geodetic points in view of experiments lay out in the North Area.