  The electron cloud is a possible heat source in the superconducting undulator
(SCU) designed for the Advanced Photon Source (APS), a 7-GeV electron
synchrotron radiation source at Argonne National Laboratory. In electron cloud
generation extensive research has been done, and is continuing, to understand
the secondary electron component. However, little work has been done to
understand the parameters of photoemission in the accelerator environment. To
better understand the primary electron generation in the APS; a beamline at the
Australian Light Source synchrotron was used to characterize two samples of the
Al APS vacuum chamber. The total photoelectron yield and the photoemission
spectra were measured. Four parameters were varied: surface roughness, sample
temperature, incident photon energy, and incident photon angle, with their
results presented here.
