November 2010


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Ellery Frahm <[log in to unmask]>
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JEOL-Focused Probe Users List <[log in to unmask]>
Mon, 15 Nov 2010 08:50:04 -0600
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Electron Microprobe Lab, University of Minnesota

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Good morning, probe folks,

I'm working with a student to analyze iron carbides, and we are trying to optimize the detector's bias voltage for carbon (this is, of course, a gas-flow proportional detector).  We did a pulse-height analysis (SCA) scan from 1600 to 2000 volts, and the greatest signal was at about 1888 volts.  The software, though, will not allow us to set the bias voltage higher than 1850 volts, and the manual makes to reference to using a voltage beyond 1800 volts.  I've tried looking around the JEOL software, and I can't find where this maximum value is set.  Does anyone know the maximum bias voltage for which the detectors are rated?  Can they handle a bias voltage of, say, 1900 volts?  Does anyone know how to increase the maximum bias voltage in the software?  Has anyone tried this and encountered a problem?  Thanks in advance for your advice.


Ellery Frahm, Ph.D.
Manager & Principal Analyst, Electron Microprobe Laboratory
Postdoctoral Associate, Department of Geology & Geophysics
University of Minnesota - Twin Cities