Performance of a GaAs electron source

none12We discuss the performance improvement of a GaAs electron source. High quantum yield (14%) and constant current extraction (1 mA for more than four weeks) are achieved after a little initial decay. These parameters meet the requirements for application of the GaAs photocathode as a source for electron cooling devices. We also present the preliminary results of a surface analysis experiment, carried out by means of the RBS technique to check the hypothesis of cesium evaporation from the surface when the photocathode is in operation.noneR. CALABRESE; G. CIULLO; G. DELLA MEA; G.P. EGENI; V. GUIDI; G. LAMANNA; P. LENISA; B. MACIGA; V. RIGATO; V. RUDELLO; L. TECCHIO; B. YANG, S. ZANDOLINCalabrese, Roberto; Ciullo, Giuseppe; G., DELLA MEA; G. P., Egeni; Guidi, Vincenzo; G., Lamanna; Lenisa, Paolo; B., Maciga; V., Rigato; V., Rudello; L., Tecchio; B. YANG, S. ZANDOLI

Surface analysis of a GaAs electron source using rutherford backscattering spectroscopy

We experimented with Rutherford backscattering spectroscopy to measure the amount of cesium on the surface of a GaAs photocathode activated in negative electron affinity (NEA) conditions. The surface analysis was performed both immediately after activation of the source in NEA condition and also some time after its total spoiling. Results showed that cesium did not desorb from the GaAs surface. With any further cesium feeding to reactivate the surface, the cesium accumulated on the surface until a saturation level was reached