vacuum, condensation

[Hugo Schwarz]

About condensation: during my previous job at MSSL we used various types of 
vacuum systems, and a safety feature was either a separate vacuum pumped 
volume which would suck out contaminants when the vacuum in the working volume 
became less than a certain value. This can be constructed in a "passive" way 
as Jaap suggested. 

Another thing is the use of getters. Is this done in CCD dewars? If not it 
might be a good idea to remove more of the "hard to outgas" contaminants. Does 
anyone know how sensitive the QE of a CCD is to small amounts of contaminants? 
Significant gains may be had.....

Hugo

hschwarz at eso.org