SESSION IX: THEORY OF DEFORMATION ANALYSIS I 346 The 10th FIG International Symposium on Deformation Measurements Situation Analysis and Stability Evaluation of Large Electron Positron Collider in CERN*

LEP (Large Electron Positron Collider) is the largest particle accelerator in the world. It was installed in tunnel underground and on service from 1989. The physicists and surveyors in CERN are very concerned with the stability of the tunnel and the accelerator. Several monitoring methods have been used for supervising. Especially, an annual global leveling is carried out from 1992 to 1999. The paper presents the methods used for the situation analysis and stability evaluation of LEP, and shows some interesting results. The dynamic features of the accelerator and the tunnel were discussed. Some statistical parameters are proposed to be as the indexes of degradation and stability, which can truly reflects on the situation of LEP. Also some researches are also done about possibility of using in the stability and deformation analysis of the large linear or curvilinear objects, such as large accelerators, tunnels, bridges, highways and railways. 1