Lifetime measurements of high polarization strained-superlattice gallium arsenide at beam current >1 milliamp using a new 100kv load lock photogun

A new GaAs DC high voltage load lock photogun has been constructed at Jefferson Laboratory (JLab), with improved vacuum and photocathode preparation capabilities. As reported previously, this gun was used to study photocathode lifetime with bulk GaAs at DC beam currents between 1 and 10 mA. In this submission, lifetime measurements were performed using high polarization strained-superlattice GaAs photocathode material at beam currents to 1 mA, with near bandgap light from a fiber based drive laser having picosecond optical pulses and RF time structure.