-\section{Experimental Difficulties / Detailed stuff / Appendix}
-\subsection{TCS}
-\begin{itemize}
- \item Optimise setup of gun
- \begin{itemize}
- \item Emission current. How much does it vary, why does it vary.
- \item Why does Is/Ie curve shift with successive sweeps? Does sweep modify sample's surface?
- \item Is sample holder acceptable? Are ceramic washers accumulating charge?
- \item How do I tell when the setup is optimised...
- ``The setup was optimised by looking for an S curve''. Very scientific.
- \item The gun was focused on the phosphor screen... and then I turned it around, changing the distance from the gun to the sample. Brilliant.
- \end{itemize}
- \item Obtain TCS spectra for Si that compares well with literature
- \begin{itemize}
- \item How to relate TCS spectrum to $n(E)$ and $E(\vect{k})$
- \end{itemize}
- \item Prepare Au films, obtain TCS spectra that compares with literature
- \item Obtain TCS spectra of Black-Au films
- \item Use results to compare properties of films with results from other methods in the literature
- \item Uncertainties
- \begin{itemize}
- \item Oscilloscope measurements of inputs to ADC channels under controlled conditions
- \begin{itemize}
- \item Expected values are +/-3mV due to ADC channel, +/-300mV due to 610B, +/-1mV due to 602
- \item 610B and 602 will probably be worse because they are ancient
- \item There is about 200mV of noise between the GND of the ADC box and the electron control box.
- \item How to reduce ground loops? Not much I can do. Rack is now also grounded to water pipe, but this doesn't seem to make a difference.
- \end{itemize}
- \item Stupid 50Hz AC noise... how to reduce with filters and/or averaging
- \end{itemize}
- \item Create circuit diagrams for Electron gun circuit
- \item Create circuit diagrams for ADC/DAC box
- \begin{itemize}
- \item Simulate behaviour of circuit
- \item Use of instrumentation amplifier on ADC5 to make off-ground measurements
- \item Use of low pass filter on ADC5
- \end{itemize}
- \item Include references to all datasheets, etc
- \item Vacuum chamber
- \begin{itemize}
- \item Base pressure with rotary pump? Was 1e-3 after 30 minutes at start of year, but probably introduced leaks since then
- \item Lowest pressure achieved with turbo pump is 1.1e-7 mbar as of 25/07.
- \item Viton gaskets on some seals. Copper on other.
- \item Flanges:
- \begin{enumerate}
- \item View window (large, view of sample \& sputtering filaments)
- \item Rotation manipulator \& sample mount
- \item Pump inlet
- \item Filament flanges 1 (used earlier in year, not anymore) and 2
- \item Inlet with leak valve (for introducing gases into chamber)
- \item Vent valve on turbo pump
- \item Electron gun flange
- \item View window (small, view of back of electron gun)
- \end{enumerate}
- \end{itemize}
-\end{itemize}