Weekend work on system ....

John Shott shott at stanford.edu
Thu May 29 16:07:30 PDT 2008

AMTetcher fans:

You may have noticed that Cesar has reserved the amtetcher this 
weekend.  We are planning on doing some significant work that, we 
believe, may address some of the late night pumpdown issues.

In particular, we plan to:

1. Replace the O-rings that seal the hexode rotation assembly.  We've 
seen intermittently high rate of rise that would be consistent with a 
marginal seal on this rotating surface.

2. Replace the liner of the bell jar and clean the inner surfaces of the 
bell jar.  This represents a lot of surface area that can capture 
moisture when the bell jar is open.

3. Clean other internal surfaces while things are stripped out of the 

This represents a significant tear down effort and one that has not been 
tackled in some time.  We feel, however, that this will result in better 
vacuum performance.  While I won't yet guarantee that this will resolve 
the post-midnight pumping problems, I'm hopeful that we'll see more 
consistent pumpdown performance after this rebuild.  We'll keep you posted.

Thank you for your continued support,


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