Author Topic: very low counts in standards  (Read 133 times)

Alejandro Cortes

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very low counts in standards
« on: July 12, 2024, 06:49:37 AM »
While our Jeol is being repaired I decided to venture in the cameca instrument we also have for the first time. I am experiencing issues with counting on standards. Peak positions are found effectively but retrieving less than 2k cts. While for Si (Spec 4 TAP-Albite) and Na (Spec 2 LTAP-Albite) this is fine, Al is really bad (Spec 4 TAP - Corundum). I though this had to be with column alignment but then why is it good for some elements and bad for others... Any input will be greatly appreciated.
 

Probeman

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Re: very low counts in standards
« Reply #1 on: July 12, 2024, 07:15:07 AM »
While our Jeol is being repaired I decided to venture in the cameca instrument we also have for the first time. I am experiencing issues with counting on standards. Peak positions are found effectively but retrieving less than 2k cts. While for Si (Spec 4 TAP-Albite) and Na (Spec 2 LTAP-Albite) this is fine, Al is really bad (Spec 4 TAP - Corundum). I though this had to be with column alignment but then why is it good for some elements and bad for others... Any input will be greatly appreciated.

That sounds like spectrometer alignment issues to me.   

Usually this requires a service engineer but if you have instructions it can be done by any competent technician.  For alignment of TAP spectrometers one first vents the instrument, then removes the spectrometer covers and all column separation windows (of the low pressure spectrometers) and replace them with Mylar windows. Then pump the column down again, but leave the covers off the spectrometers so they are at atmosphere. One then utilizes high order reflections (i.e., Fe ka 4th order) to perform the spectrometer alignments.

Be careful to keep your hand out of the x-ray beam coming through the Mylar windows!
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