[RASMB] intensity issues

[Leech, AP]

Hi Borries,

Your plot gives the intensity as a function of scan number; it would
be interesting to see whether the period of the fluctuation is a
constant time (implying some slow cycling process in the machine, maybe
cooling or vacuum?); or related to speed or interval between scans
(perhaps implying some kind of curious timing problem).

Do you know if the period changes at different speeds?

Best regards,

Andrew

Borries Demeler wrote:
> Dear Colleagues,
> 
> I have an issue with an XLI at FSU - it has a strange problem with
> intensity. First, it is very low, and second, it has a regularly spaced 
> intensity oscillation. Please see the attached image. It was generated
> by scanning a channel containing just water in intensity mode and 
> averaging the intensity in the flat region over all points. The plot
> shows the average intensity of the scans over a number of scans. The
> entire run shows this consistent intensity fluctuation, and it is 
> apparent in all cells. The run was done at 50,000 rpm. Does anyone
> have a good suggestion as to what flaw in the XLI could potentially
> cause such a pattern? Is this a lamp firing issue, or a voltage issue
> with the PM tube or flash lamp? The machine was just newly installed
> and configured by Beckman service, and this is the pattern it produces.
> 
> Thanks, -borries
> 
> 
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-- 
Dr Andrew Leech                   *  Laboratory Manager
Technology Facility               *  Molecular Interactions Laboratory
Department of Biology (Area 15)   *  Tel   : +44 (0)1904 328723
University of York                *  Fax   : +44 (0)1904 328804
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