[RASMB] lamp intensity drop

[Tom Laue]

Hi Dror-
That is about normal. If the problem gets worse (i.e. fewer than a 
couple of hundred scans before cleaning is needed), it is likely that 
there is a slow vacuum leak in your system.
Best wishes,
Tom

Dror Noy wrote:

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> Hi all,
> We encounter a very annoying behavior in our XLA and I'd like to check 
> with the forum if this is a specific or general problem.
> After running many scans the UV intensity of the flash lamp is reduced 
> dramatically. This is caused by some kind of chemical reaction at the 
> lamp surface that makes a brownish hallow that absorbs UV. It is a 
> known phenomenon and Beckman recommends cleaning the lamp surface with 
> tooth paste abnd tooth brush. It really works. Our problem is that it 
> happens too frequently on our machine. My recent observation is that 
> it took about 750 radial scans (6.0 to 7.2 cm at 0.003 cm step) to 
> decrease the intensity at 230 nm by half. Does this look like a 
> "normal" half-life?
> Thanks,
> Dror
> =========================
> Dror Noy, Ph.D.
> Structural Biology Dept.
> Weizmann Institute of Science
> Rehovot 76100
> Israel
>
> e-mail: dror.noy at weizmann.ac.il
> Tel: (972)-8-934 2525
> Fax: (972)-8-934 4154
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