\chapter{Concluding the Module Assembly}

At this stage the module is almost ready to be installed into the MEGHA scattering chamber. After testing, the only job that remains is to replace the blanking plate on the module vessel, with a mylar window and calibration grid.
Remove all bias, power and pulsers from the pre-amplifier packs and CsI scintillators. 

\begin{figure}[ht]
\vspace{14cm}
\special{psfile = /home/oed/Modprotocol2/mylar.ps
hscale=110 vscale=110 hoffset=-75 voffset =-210}
\special{psfile = /home/oed/Modprotocol2/clamp.ps
hscale=110 vscale=110 hoffset=-85 voffset =-450}
\caption{MEGHA mylar window (top). MEGHA window clamp (bottom).}
\end{figure}

During testing a blanking plate was screwed onto the front of the module vessel. This will now be replaced with a mylar window and clamp (see Figure 6.1). The mylar window is placed against the vessel O-ring, such that the aluminum frame (of the window) is facing away from the vessel. In this way the mylar forms the vacuum seal against the vessel O-ring. The window is secured in place by the window clamp. The window clamp sits on top of the mylar frame and is secured down using sixteen M4 16mm allen head screws. These screws should be vacuum relieved. 
To guarantee correct seating of the vessel O-ring follow the same procedure of tightening the screws as was adopted for the glass feedthroughs (i.e. opposite corners).
The clamp must be put onto the vessel such that the two protruding dowels (which allow correct seating of the calibration grid) face outwards.
\newline
\newline
N.B. \em The mylar windows are fragile, and should be handled carefully. A technique to test the vacuum integrity of the mylar windows (prior to use in MEGHA), is being designed, and will be outlined in this manual once completed.
\newline
\newline
\rm To protect the mylar window while installing the module into the scattering chamber, the calibration grid is screwed onto the front of the window clamp. Using four M2.5 8mm vaccum relieved screws

The centre module has a specially adapted mylar window and window clamp, to allow for the beam-pipe, which passes through the centre module. See Figure 6.2.

\begin{figure}[ht]
\vspace{14cm}
\special{psfile = /home/oed/Modprotocol2/Cmylar.ps
hscale=110 vscale=110 hoffset=-75 voffset =-190}
\special{psfile = /home/oed/Modprotocol2/Cclamp.ps
hscale=110 vscale=110 hoffset=-75 voffset =-425}
\caption{Centre module mylar window (top). Centre module window clamp (bottom).}
\end{figure}




