Development of Vacuum Chambers in Low Z Material

Highly transparent vacuum chambers are increasingly required in high energy particle physics. In particular, vacuum chambers in the experiments should be as transparent as possible to minimize the background to the detectors, whilst also reducing the material activation. Beryllium is, so far, the most performant material for this application, but it presents some drawbacks such as brittleness, manufacturing issues, toxic if broken, high cost and low availability. A development work to obtain an alternative material to beryllium with similar performance is being carried out at CERN. Three categories have been defined and considered: raw bulk material, material composites and structural composites. The main functional requirements are: vacuum compatibility (leak tightness, low outgassing rate), temperature resistance (in the range 200-230 °C), transparency, and mechanical stiffness and strength. After beryllium, carbon is the element with the lowest atomic number that is practical for this application; therefore carbon based materials have been considered in a variety of options. In this paper, several technologies are presented and discussed. Results of preliminary tests on samples are also shown.