1. Updates: Characterization and Aging
Slade J. Jokela, Igor V. Veryovkin, Alexander V. Zinovev

2. Thickness Series
Al2O3 and MgO samples have been tested under new setup
Al2O3 samples were also provided by Mike Pellin
Samples’ surface roughness are well known

3. MgO Revisited
Old Data
New Data

4. MgO Revisited
Differences in emission is due to changes made in procedure
Sample is now held at constant potential, incident electron energy is varied inside the electron gun
Some form of field assisted emission is partially responsible for higher emission and decreased emission for higher energies in old data
In old data, sample bias approached zero for high energies
Sample contamination may also be responsible for some emission changes (exposure to moisture or atmosphere?)

5. Al2O3 Thickness Series

6. Al2O3 Thickness Series
Data is very noisy, especially compared to similar samples (shown on next slide)

7. Pellin-Provided Al2O3

8. Pellin-Provided Al2O3 Emission is much higher than expected
One cycle is approximately a half-monolayer (0.5Å)
Suspect that surface contamination is responsible
For some reason, data is less noisy even though nothing has changed except the sample

9. XPS of Al2O3 Samples O C Al Si

10. Future Possibilities on MCP Aging
In the past, we have experienced increases in emission for MgO and decreases in emission for Al2O3 films
At present, the only studies we can perform are
Emission as a function of primary electron fluence
XPS peaks as a function of primary electron fluence
XPS can only be performed on large areas, so different electron gun must be used (not compatible with simultaneous SEY measurements)
Auger spectroscopy doesn’t seem to be sensitive enough for simultaneous aging and composition measurements.
Also, incident electron current must be decreased to prevent charging of lens elements in hemispherical analyzer