Mastering beam losses and ageing issues at the ESRF

The ESRF accelerators have been in full routine operation for more than four years. The source delivers nearly 5600 hours of X-ray beam to 40 beam lines simultaneously, which in turn perform about 700 experiments (or 70.000 hours of experimental work) per year. To maintain free access in the experimental hall only public dose rates are allowed. However, with the installation of small aperture vacuum vessels in straight sections a dramatic increase of bremsstrahlung outside the corresponding optic hutches was experienced. Hence, thorough studies to understand and master beam losses have been undertaken. This required the development of a beam loss detection system and the adoption of the strategy of using scrapers for beam collimating. In addition, great care is taken to detect the first traces of ageing of equipment (for example due to irradiation) and therefore avoid, as far as possible, failures. It is indeed true to say that the more failures there are, the more the beam losses and the more the dose level!