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May 2009

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Subject:
From:
Ellery Frahm <[log in to unmask]>
Reply To:
JEOL-Focused Probe Users List <[log in to unmask]>
Date:
Wed, 20 May 2009 22:15:52 -0500
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*

Ron Rasch wrote:

> . . . My big problem right now spectrometer reproducibility. The  
> spectrometer doesn't always go back to the correct position, giving  
> me a count rate that varies by too much (eg 5% measuring the Ka of a  
> pure metal).  Any advice on what to check next?
>
> cheers,
> Ron


Hi Ron,

About your spectrometer reproducibility issue, what have you tried,  
and what are the symptoms?  Is this a 8600 or 8900?  Does your  
spectrometer have problems at all L levels, or just high or low ones?   
When moving in both directions or just one?  How does peak shape  
affect your drop-off (e.g., Si vs Fe)?  What happens if you re-peak,  
say, a hundred of times and track the L values?  Any trends?  What  
about the counts if you repeak each time?  Those okay?  What happens  
if you swap the stepper motor with that from another spectrometer?  I  
assume that the other spectrometers are functioning normally.

Best,
Ellery

-----------------
Ellery Frahm
Manager & Principal Analyst, Electron Microprobe Lab
Senior Research Fellow, Department of Geology & Geophysics
University of Minnesota - Twin Cities
http://probelab.geo.umn.edu

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