Intrinsic electron beam emittance from metal photocathodes: the effect of the electron effective mass.

A theoretical development of prior analyses, together with our solenoid scan measurements on eight planar metal photocathodes (Ag, Be, Cr, Cu, Mo, Sn, Ta, and W) and previous data on Mg [X. J. Wang, M. Babzien, R. Malone, and Z. Wu, in Proceedings of LINAC2002, Gyeongju, Korea, 2002 (Pohang Accelerator Laboratory, Pohang, Korea, 2002), pp. 142-144.] indicate that the transverse momentum (and hence intrinsic emittance) of an electron beam is fundamentally dependent on the electron effective mass in the metal.