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

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

MgO Revisited Old Data New Data

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?)

Al2O3 Thickness Series

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

Pellin-Provided Al2O3

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

XPS of Al2O3 Samples O C Al Si

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