Lowest mean transverse energy obtainable from a photocathode · revision history

Revision 2

Accepted · core change · record

Changes against revision 1:

Title
Lowest mean transverse energy obtainable from a photocathode
Plain
Electrons leave a cathode with some random sideways energy that blurs the beam; how low it can go, and what sets the floor, is open.
Precise · changed · core
Revision 1: The intrinsic normalized emittance of a photoemission source is eps_n = $\sigma_x$ sqrt(MTE/(m c^2)), with sigma_x the rms source size and MTE the mean transverse energy of emitted electrons. Values of approximately $5\,\mathrm{meV}$ were reported around 2020 from near-threshold photoemission of cryogenically cooled single-crystal Cu(100). Determine the lowest achievable MTE at quantum efficiency $\ge 1e-5$ and the physics that sets it (lattice temperature, surface roughness and work-function variation, electron-phonon and electron-electron scattering, multiphoton emission).
Revision 2: The intrinsic normalized emittance of a photoemission source is eps_n = $\sigma_x$ sqrt(MTE/(m c^2)), with sigma_x the rms source size and MTE the mean transverse energy of emitted electrons. Values of approximately $5\,\mathrm{meV}$ were reported around 2020 from near-threshold photoemission of cryogenically cooled single-crystal Cu(100). Determine the lowest achievable MTE at quantum efficiency $\ge 10^{-5}$ and the physics that sets it (lattice temperature, surface roughness and work-function variation, electron-phonon and electron-electron scattering, multiphoton emission).
Settled by
MTE measurements versus temperature, photon energy and surface preparation on candidate cathodes, matched by a photoemission model including the surface.
Kind
well-posed
Answer type
value
References
(empty)
Literature status
open
Status note
(empty)
Posed since
(empty)

Decisions