Coldex: A tool to study cold surfaces in accelerators

With the advent of more and more accelerator machines based on superconducting technology, the detailed understanding of the cryogenic vacuum system is of primary importance for the design and operation of modern machines. COLDEX was built to study the beam / cold surfaces interactions in LHC in the context of the electron cloud build-up. This paper reviews the main results obtained with COLDEX for Cu, the LHC material and a-C coating the proposed anti-multipacting surface for the LHC upgrade. It presents also recent results obtained with a laser treated surface, a potential anti-multipacting material for the next generation of colliders operating at cryogenic temperature.