Zero or negative counts for MAN background correction

[dawncruth]

Hi all,
Has anyone seen the following error:

"Standard number XX ka MAN background corrected counts are zero ore negative on channel X"

For me this is for Si on channel 1, with TAP for the crystal.  So, important.

Other standard MANs are fine for Si on channel 1.  I tried recalibrating, reassigning MAN fits, etc.  I'm at a loss.

Cheers,
Dawn

[John Donovan]

Hi all,
Has anyone seen the following error:

"Standard number XX ka MAN background corrected counts are zero or negative on channel X"

For me this is for Si on channel 1, with TAP for the crystal.  So, important.

Other standard MANs are fine for Si on channel 1.  I tried recalibrating, reassigning MAN fits, etc.  I'm at a loss.

Cheers,
Dawn

Hi Dawn,
It means that that MAN standard has zero counts on that channel.

Use the List Standard Intensities button (or List Report button on older versions) in the Analyze! window to see the offending standard and delete it.

This is really just a sanity check in the software, because I'm not sure how one could acquire a negative intensity on an MAN standard because MAN standards are only measured on-peak.  Maybe you have an interference assigned that isn't actually present and it is over correcting it to such an extent that it goes negative?
john

Edit by John: I just realized that the List Standard Intensities button in the Analyze! window will produce the same error, so I will add the standard set number to the error message as an aid to tracking down the offending standard. In the meantime simply display the raw data (from the Analyze! window) and go through all sets of that standard number and find the offending standard. 

Of course if the problem is indeed that an interference correction is being assigned when there is actually no interference present, that adjustment occurs dynamically when loading the standard intensities, and so the negative counts won't be visible in the raw data. In this case, you might try turning off the interference correction globally from the Analytical | Analysis Options menu dialog and see if that fixes the issue.