Speaker
Description
In FCC-hh one of the most challenging issue will be the control of all possible instabilities that could occur. In order to do so, all vacuum vessel inner surfaces need to be characterised in great details. Among others properties, their Secondary Electron Yield (SEY), Photo Yield (PY), Reflectivity (R) and their capability to adsorb residual gas molecules and maintain them absorbed during temperature fluctuations are of paramount importance to address machine operation issues. All those parameters need to be studied in experimental conditions as close as possible to the ones that will occur. Also, their stability during operation must be addressed thoughtfully.
Most of the accelerators walls will see the beam while being at low temperatures and some of their relevant properties will not only depend on the technical materials in use but also on the presence of cryosorbed ice of residual gases condensed on them. Such gas layers may affect SEY and vacuum stability in case of temperature fluctuations.
At LNF, also thanks to the availability of Synchrotron Radiation light, we can analyse, with a multidisciplinary approach, most of those aspects contemporarily and in experimental conditions close to reality. For low temperature unbacked materials SEY, temperature-, photon- and electron-induced desorption, grazing angle R and PY have been and are under study. Results will suggest important guidelines and input to simulation programs used to validate any proposed design.
