[RASMB] Lamp Intensities on Analytical Ultracentrifuges

[John E Harlan]

I am starting to have some problems with rapidly decreasing lamp 
intensities on my analytical instruments.  Within about 1 month of 
moderate use after my service people were in (they cleaned the optics 
while checking other things), I find the noise in my velocity absorbance 
scans is quite bad.   When I check the intensities I find maxima at 230nm 
to be 8300 for an XLA and 13000 for an XLI, well below the 20000 to 30000 
I should find for a well functioning instrument.

I have two questions:

1)  What could cause such a rapid decay of performance.  I suspect oil 
leaks fouling the optics (I have observed droplets in the can on at least 
one occasion).  I understand alignment can also cause problems.  Is there 
something else to ask my service people to check?

2)  I have heard that people that have upgraded to a turbo-molecular 
vacuum pump have been quite pleased with performance.  Can this upgrade 
help keep my optics clean, if indeed that is the problem?

Thanks for your help in advance.

John
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