Francisco Gontad

Department of Mathematics and Physics "Ennio De Giorgi" Instituto Nazionale di Fisica Nucleare (INFN) Sezione di Lecce Via per Arnesano, 73100 Lecce, Italy

Preparation of metallic thin film photocathodes by pulsed laser deposition



The development of metallic photocathodes is a research field of great interest both for the fabrication of high brightness electron beam sources and in the area of free electron laser and collider applications. Although semiconductor photocathodes present lower work functions and higher quantum efficiencies (QEs), metallic photocathodes provide shorter response photoemission time, superior robustness and longer lifetimes, which make them very exciting alternatives in the area of interest. For that reason, a large number of metals have been studied exhaustively for their implementation in further technological applications.
Despite the huge research effort for the fabrication of thin film metallic photocathodes for conventional radiofrequency (rf) guns, the production of high appreciable average currents (>1 mA) in near continuous wave (CW) operation requires the development of a photoinjector based on superconducting technology. However, the material used for the fabrication of superconducting radiofrequency (srf) cavities, Nb, presents a low QE, demanding the use of an alternative material for the fabrication of the photocathode. This drawback can be overcome by incorporating a Pb photocathode into the Nb srf cavity, taking advantage of its superior QE and its similar critical temperature to Nb.
In this presentation, the fabrication of metallic thin film photocathodes for both conventional rf-guns and srf-guns will be discussed, focusing special attention to the preparation of srf photocathodes through pulsed laser deposition.

Date: 14/5/2014
Time:12:00 (coffee & cookies will be served at 11:45)
Place:FORTH Seminar Room 1