1. Update on APS Testing

2. No Observed Signal from MCP
Tests were performed
with laser and UV LED
both with and without photocathode
while biasing each plate individually and both plates together
with highest voltage across both plates reaching 3 kV (at the end of testing only)
Current started to run away, but I quickly turned off the power supply.
Current never exceeded 3 milliamperes (9 Watts)
No signal was observed on the strip lines
Resistance changed radically with time
By the end, resistances of the plates (originally different by a factor of 10) was pretty close.
Resistances were non-Ohmic
12/1/2018
Collaboration Meeting

3. Examination of Plates After Testing
Some scratches and gold flecking off (probably not important)
Evidence of overheating
Unknown marks on plate edge
12/1/2018
Collaboration Meeting

4. Examination of Plates After Testing The Discolored Area Close Up
12/1/2018
Collaboration Meeting

5. Collaboration Meeting
Plate Resistances
MCP 7 went from ~107 to ~108 Ohms
MCP 8 went from ~105 to ~108 Ohms
Qing et al
12/1/2018
Collaboration Meeting

6. Collaboration Meeting
What went wrong?
Unwanted material in the MCP reduced the effective resistance. “Baking” helped.
In the process of applying high voltages, some channels probably over-heated.
Were the channels themselves actually damaged or did we just melt some of the gold?
What exactly did we do to the MCP during testing?
Or is the problem more serious: crystal imperfections? Improper Doping?
Further studies are necessary to understand the nature of the ALD coatings
12/1/2018
Collaboration Meeting

7. Collaboration Meeting
Immediate Next Steps
Improvements to setup.
Shorter cabling
Much smaller MCP-anode gap
Looking into making a well defined, well understood gold photocathode to produce photoelectrons
A control sample in the new sample (the ALD-coated commercial plates) this week.
First testing 1 functionalized channel plate with 1 commercial channel plate
Sample from Arradiance?
12/1/2018
Collaboration Meeting