Characterization of the GaAsSb Photocathode
with the Micro-Mott Electron Polarimeter
Electron beam in the accelerator at Jefferson Lab is currently produced using GaAs:GaAsP photocathodes. However, SVT Associates, a manufacturer of semiconductor photocathodes, recently began working with Jefferson Lab to characterize a new kind of GaAs superlattice: GaAsSb:AlGaAsP. This structure is anticipated to have comparable yield and polarization values to the established GaAs:GaAsP crystals, but with longer operational lifetime at high voltages. The micro-Mott polarimeter in the EEL is being used to characterize the electron yield and polarization of the new cathode across various wavelengths. Polarization values are about 15% lower in GaAsSb:AlGaAsP than in GaAs:GaAsP, however, discrepancies within the system have prevented conclusions from being drawn about electron yield.