1. Characterization Update
Slade J. Jokela

2. Recap of some past work Emission vs. thickness 2 sets of Al2O3 MgO
One set is years old (exposed to air)
MgO

3. Alumina Samples
Pellin Samples most likely have O-H adsorbed to the surface

4. Alumina vs. MgO

5. Interesting Emission Phenomenon
Late last week I noticed a continuous current from one of the Al2O3 MCP monitor coupons and 0.5mm thick saphire.
-200 V sample bias
Approximately 10 seconds (continuous) of 300eV electron exposure (500eV electrons from gun)
Beam current around 100 nA
Beam diameter 500 microns or smaller
Emission climbs from a gain of about 2 to a gain of about 10 (no data gathered yet, only observations)
After electron beam is shut off, emission continues with a current in excess of 1 microamp
Emission lasts for approximately 10 minutes, decaying seemingly exponentially (data collection needed).
Emission appears to be field related (LEED phosphor screen).
While there may not be sharp points on the surface, electron beam can induce very small pockets of charge with very large field gradients.

6. Continued Emission
I will examine this closer to determine if it is affecting my pulsed measurements.
Regardless, this is something we should watch for in MCPs under high current exposure