FEL2011 - List of Authors (Greaves, C.M.R.)

Paper	Title	Page
THPB15	Metal Cathodes with Reduced Emittance and Enhanced Quantum Efficiency	586
	C.M.R. Greaves, J. Feng, H.A. Padmore, W. Wan LBNL, Berkeley, California, USA D. Dowell AES, Princeton, New Jersey, USA
	In this paper, we report experimental results on photoemission from copper and silver surfaces. Using the technique of angle resolved photoemission spectroscopy (ARPES), we demonstrate that, for excess energy around 0.5 eV, the photoelectrons from the Cu(111) and Ag(111) surfaces generated by p-polarized light originate primarily from the well-known surface state with normalized emittance only a fraction of that of the polycrystalline copper cathode presently used in the RF guns. Meanwhile, we demonstrate that the enhancement of the quantum efficiency (QE) at grazing angle is closely related to the surface state as well. Furthermore, we show that the surface state can be easily restored by a simple anneal process, thus pointing to a practical way to reducing the emittance and QE of a metal cathode simultaniously.

Paper

Title

Page

Metal Cathodes with Reduced Emittance and Enhanced Quantum Efficiency

586

C.M.R. Greaves, J. Feng, H.A. Padmore, W. Wan
LBNL, Berkeley, California, USA
D. Dowell
AES, Princeton, New Jersey, USA

In this paper, we report experimental results on photoemission from copper and silver surfaces. Using the technique of angle resolved photoemission spectroscopy (ARPES), we demonstrate that, for excess energy around 0.5 eV, the photoelectrons from the Cu(111) and Ag(111) surfaces generated by p-polarized light originate primarily from the well-known surface state with normalized emittance only a fraction of that of the polycrystalline copper cathode presently used in the RF guns. Meanwhile, we demonstrate that the enhancement of the quantum efficiency (QE) at grazing angle is closely related to the surface state as well. Furthermore, we show that the surface state can be easily restored by a simple anneal process, thus pointing to a practical way to reducing the emittance and QE of a metal cathode simultaniously.