Arrive 9:30am

Was last in lab on 2012-09-20
 - Left TCS experiment to take TCS of Si substrate 
 - Yesterday, briefly came in... program had crashed due to failed pressure reading
   - Removed pressure reading from program, and restarted. But effectively, 6 days lost.
   - The TCS now is very different to on 2012-09-20. I had hoped that I could see the gradual change.
     - But program crashed after ~2-3 hours

- Check and compare electron gun parameters

On the 20th
# Venault Voltage = 10.34
# Accelerating Voltage = 264
# Focus Voltage = 8.17
# Deflection Voltage = 0.380
# Initial Voltage = sweep
# Heating Current = 1.149
# Heating Voltage (across filament) = 1.180
# Heating Voltage (across power supply) = 1.51

Today (27th)
# Venault Voltage = 10.35
# Accelerating Voltage = 262
# Focus Voltage = 8.16
# Deflection Voltage = 0.382
# Initial Voltage = sweep
# Heating Current = 1.149
# Heating Voltage (across filament) = 1.174
# Heating Voltage (across power supply) = 1.537

Changes are negligable. => The surface has changed somehow over time
 - Batteries of ammeter are also quite low though. Will replace.

- Curves now show 2 steep increases in current; 2 different surfaces in the beam?
  - Si was originally cleaned very well. Only 1 steep increase in graphs on 20th, although possibly part of a second
  - Maybe the surface has become contaminated (SiO2 layer?)
    - A good way to check: Clean surface, do ellipsometry. Put surface in chamber, do TCS (without program crashing) over long period.
      - Then take sample out, do ellipsometry. Fit for thickness of SiO2 and compare.
      - I don't think I have time to do this.
  - Position of first increase shifted to right (higher E)

- First: Fix problem in program if pressure is bad.
  - I think I fixed it now. It required an embarrassingly small amount of work
    - If pressure reading fails, defaults to "0.0". Which it will never actually be in real life, so I can tell which measurements failed.

- Give 602 new batteries
  - Very slight shift in curve, but still clearly the same shape

- Keep gun properties the same; measure TCS of stainless steel to see what curve looks like
  - Whilst rotating sample holder, note pattern of 5 spots in a line on the Si surface
    - Preeeetty sure they weren't there before... wtf 

  - Immediately note: Order of magnitude less current for stainless steel
    - But, rotating the sample holder to ~300 deg = x10 current compared to 320 deg
      - Ie: More current when sample surface is not perpendicular to axis of gun
        - ??? Beam deflected horizontally by Earth's B field?
      - Put to 320 deg; use same orientation as for Si
  - Curve looks "unfocused"; no plateau
    - Or maybe plateau is too far to the right to see on the scale 0-17V
    - First curve looks noisy. Subsequent curve looks smoother
    - Leave for 10 mins. Curves show trend; higher max, and further to the right (higher E) as time goes on

 - Test for response of Stainless steel sample to large steps in DAC level.
   - Sample shows "charging problem" ie: exponential decay/rise on steps
 - Repeat for Si
   - Same effect
 - Will see if the effect still occurs when Au is evaporated onto the surface(s)

 - Try and get rid of the "double peak" increase in Si by focusing gun.
   - Analysis suggests Vd = -0.6 is better than previously used Vd = 0.38; only one steep increase this time
   - Will use that from now on
   - First: Take sweeps on Si, whilst having lunch

- Evaporate Au onto Si
  - pressure monitored in 1416.pressure.dat