Shape Stability of the LHC Superconducting Dipole: Mechanical Model and Experimental Investigations

The aim of this work is the study of the geometry of the main superconducting dipole for the Large Hadron Collider from the manufacturing process throughout the pre-operative stages to predict the respect of the tight tolerance, imposed by the beam dynamic, in both nominal and chancy working conditions. Expected and unexpected situations have been approached through the development of dedicate models and tests with the purpose of evaluating their impact on magnet geometry. In our study we used structural models of different complexity for different purposes. For example we used analytical models in conjunction with the cold mass geometry database to simulate the overall effect of individual geometry corrections or to discriminate elastic from inelastic measured deformations. By means of finite element models, instead, we investigated the effect of mechanic loads as induced by road transport, or the effect of electro-magnetic forces arising in working conditions. As the assembly complexity prevents from deducing some of the main mechanical properties we set-up different tests and we evaluated the desired properties from the comparison with analytical or finite element models.