[RASMB] lamp intensity drop

[Dror Noy]

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