The investigation of supported size-selected clusters by different surface science techniques requires stringent ultrahigh vacuum (UHV) conditions during cluster deposition especially at low temperatures. The existing high-energy sputter sources used for cluster production in general do not fulfil this demand. We therefore have developed, built and tested a new fully bakeable ultrahigh vacuum-compatible version of the cluster source CORDIS (Cold Reflex Discharge Ion Source). As a first application, we present ultraviolet photoemission spectra (UPS) of size-selected clusters generated by this new cluster source and deposited on highly oriented pyrolytic graphite (HOPG). We show evidence for cluster diffusion and island formation even down to low temperature (T = 70 K). These islands display a polycrystalline structure. After a short annealing, they are transformed into Ag films with (111) surface orientation.