Author Topic: 8230 spectrometer offsets  (Read 960 times)

UoL EPMA LAB

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8230 spectrometer offsets
« on: March 16, 2018, 09:03:38 am »
Hi

I've had some work done on spc2. I ran a spectrometer calibration afterwards.
When I peak up I am seeing a notification about a large peak offset.
What does this mean and what should I do about it?

Richard

John Donovan

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Re: 8230 spectrometer offsets
« Reply #1 on: March 16, 2018, 09:56:04 am »
I've had some work done on spc2. I ran a spectrometer calibration afterwards.
When I peak up I am seeing a notification about a large peak offset.
What does this mean and what should I do about it?

Hi Richard,
Nothing to be alarmed about.

The software is merely warning you that the difference between the theoretical peak position and where the peak was actually found is off by a value greater than the fractional tolerance specified in the SCALERS.DAT file on line 34:

400.     400.     400.     400.     400.  "Spec offset warning factors"

In this example one would get a warning if the spectrometer offset is larger than 1/400th of the spectrometer range, or roughly 0.5 mm of your spectrometer L units.

The reason this warning is problematic is because each vendor utilizes a different table for the ideal spectrometer positions. So if you want, you can edit this value in the SCALERS.DAT file and change it to say 200 and you won't see the warning.  However, you do have to ask yourself: why is the offset from the theoretical position almost 0.8 mm?

On the Cameca we usually want to see the peak positions within about +/-100 spectro units of the theoretical peak position.  That corresponds to a spec offset warning factor of ~600.

john
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UoL EPMA LAB

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Re: 8230 spectrometer offsets
« Reply #2 on: March 19, 2018, 07:22:41 am »
Thanks John

I will delve further.

Richard