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 throughout the various steps of the alignment process. One of these steps is the survey, which aims to determine the position of the machine's components and thereby reconstruct its entire geometry. This is a critical step, as it is the final one that determines whether the components comply with the specified tolerances. If this step introduces excessive uncertainty in the position of the components, it can lead to bad decisions, such as validating a non-conforming alignment or, conversely, rejecting an alignment that is in fact correct. A measurement campaign was therefore conducted, in which seven surveys of the storage ring were performed 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's global shape does not exceed 30 µm in any of the three directions (k = 1), while the circumference of the machine is repeatable to better than 300 µm. Locally, at the level of an individual girder, the dispersion of the magnets does not exceed 2 µm in the three directions (k = 1).
