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The Center for Bright Beams, A National Science Foundation Science and Technology Center

Less than 10 meV MTE from Cu

S. Karkare, et al.

The brightness of electron beams is limited by the smallest possible mean transverse energy (MTE) of

Visualization of an electron beam at varying levels of MTE.

four graphs, each showing a blue background with a bright circle showing meV. Two show 8 V acceleration and two show 4 V acceleration. Each acceleration has on graph at MTE=28 meV and one at MTE=6 meV

With sub-meV energy resolution, researchers can now obtain complete energy/momentum distribution

electrons emitted from the photocathode. There are various factors that limit MTE and CBB is working to minimize each of these factors. Upon doing this, we obtained a record low MTE of 6 meV from the (100) surface of Cu. Before now, there was no instrumentation to even measure MTE this low, so we developed the technology to do this. We have not stopped, and there are various ongoing efforts within the Center for Bright Beams to obtain such small MTE along with large charge densities to increase the brightness of electron beams by two orders of magnitude.