Bremsstrahlung measurements at the ESRF

Increased bremmstrahlung radiation levels were observed around several ESRF beamlines, which had been equipped with new insertion device vacuum vessels with a reduced vertical aperture. In order to understand the origin of this increased radiation, detailed bremsstrahlung measurements have been carried out on several beamlines. This paper describes the results of these measurements. The measurements allowed the dose levels originating from the gas-bremsstrahlung component to be quantified. However, precise vertical profile measurements have clearly indicated the presence of a second bremsstrahlung component, due to a scraping effect of the electron beam at these reduced vertical apertures. It was shown that the latter component could easily be the predominant one in the radiation dose levels observed around the beamlines. The curing effect of changing the storage ring optics from a high β to a low β optics was clearly demonstrated