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November 2010

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Subject:
From:
Sergei Matveev <[log in to unmask]>
Reply To:
JEOL-Focused Probe Users List <[log in to unmask]>
Date:
Tue, 16 Nov 2010 22:59:48 -0700
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JEOL Probe Users Listserver

Moderator: Ellery Frahm, [log in to unmask],
Electron Microprobe Lab, University of Minnesota

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*

Hi Ellery,
I do not think one can override software and use HV > 1888 (I was not able to do so using HP UNIX software). I usually assume that for very light elements we can get only that far with 128 gain and 1800 HV. The BL peak might be pretty low and will never be even close to 2 (in our case), I just assume it is a fact of life for LDE crystals. 
Best regards,
Sergei

On 2010-11-15, at 7:50 AM, Ellery Frahm wrote:

> JEOL Probe Users Listserver
> 
> Moderator: Ellery Frahm, [log in to unmask],
> Electron Microprobe Lab, University of Minnesota
> 
> Post a message: send your message to [log in to unmask]
> 
> Unsubscribe: send "SIGNOFF PROBEUSERS" to [log in to unmask]
> 
> On-line help and FAQ: http://probelab.geo.umn.edu/listserver.html
> 
> 
> 
> *
> 
> 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.
> 
> Best,
> 
> Ellery Frahm, Ph.D.
> Manager & Principal Analyst, Electron Microprobe Laboratory
> Postdoctoral Associate, Department of Geology & Geophysics
> University of Minnesota - Twin Cities
> http://probelab.geo.umn.edu
> 



-- 
Sergei Matveev, Ph. D.
Electron Microprobe Laboratory,
Department of Earth and Atmospheric Sciences,
University of Alberta
http://research.eas.ualberta.ca/eml/index.html

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