Speaker
Description
The SOLEIL II machine upgrade requires unprecedented alignment tolerances, down to +/- 20 µm for the most critical magnets of the storage ring. This specification demands full control of measurement uncertainties during the different steps of the alignment process. For this specific purpose, a rigorous metrological approach has been developed and applied throughout the entire alignment strategy. This approach aims to characterise, optimise and monitor the performance of each measurement step. Such characterisation consisted in a measurement campaign in which seven surveys of the storage ring were carried out in succession over a period of less than three weeks. Those surveys were intended to quantify the experimental uncertainty associated with this step and to compare it against in-house simulations. The results show that the dispersion of the machine shape does not exceed 30 µm in any of the three directions (k=1). Moreover, the circumference of the machine is repeatable to better than 200 µm.
The proposed talk will introduce the metrological approach adopted at SOLEIL and will present the main results obtained. First, excellent control of the laser tracker's measurement uncertainty was achieved, better than 4 µm on the coordinates of a point at 2 m distance (k=1), through a range of characterisations and optimisations. Second, the multi-survey campaign demonstrated that a single survey provides excellent control of both the storage ring's circumference — compared against the RF frequency reference — and its global and local shape. Finally, the way alignment tolerances are simulated by physicists has significantly evolved, bringing them closer to the reality of the alignment process.
