Peak search problems

[Mike Spilde]

I've had a problem for some time with PFE not being able to find the peak if it has drifted off from its expected position. My usual work-around is to do the search with the JEOL Peak Search and then enter the new peak position into the Element/Cations window when I set up a new sample.

When PFE cannot find a peak centroid, it does a wider peak search and usually finds the peak with no problem. I'll attach an example of the second broader peak search. The Peaking routine should take that new value and start another fine search for the centroid. The problem is that it starts the fine search at some random value, usually down the trailing flank of the peak and thus cannot find the centroid because the search was started in the wrong place. In the attached example, you'll see that it found the peak in the coarse search at 120.282, but then started the fine search 120.49, half way down the right flank of the peak and used a bogus value (120.521) as the centroid. Why is PFE offsetting the search beyond the peak?

[John Donovan]

I've had a problem for some time with PFE not being able to find the peak if it has drifted off from its expected position. My usual work-around is to do the search with the JEOL Peak Search and then enter the new peak position into the Element/Cations window when I set up a new sample.

When PFE cannot find a peak centroid, it does a wider peak search and usually finds the peak with no problem. I'll attach an example of the second broader peak search. The Peaking routine should take that new value and start another fine search for the centroid. The problem is that it starts the fine search at some random value, usually down the trailing flank of the peak and thus cannot find the centroid because the search was started in the wrong place. In the attached example, you'll see that it found the peak in the coarse search at 120.282, but then started the fine search 120.49, half way down the right flank of the peak and used a bogus value (120.521) as the centroid. Why is PFE offsetting the search beyond the peak?

Hi Mike,
I do not know.  It *should* start the 2nd fine peak search centered on the coarse peak centroid if the 1st fine scan fails.  It always works for me at least!

Go ahead and update PFE and see if that helps.  In the meantime I will talk to Paul.
john

Edit by John: I talked to Paul and he says there was an issue some time ago, but I modified the code last year and now it is working properly, so please update and let us know if you still see the problem.

[Mike Spilde]

John,

Unfortunately, this is still occurring with the latest update (10.8.x). I think it started with 10.6.x.

Mike

[John Donovan]

Unfortunately, this is still occurring with the latest update (10.8.x). I think it started with 10.6.x.

Hi Mike,
This is very strange as Paul said it is not occurring on his 8200.

Would you be able to put the software in DebugMode (from the Output menu) and run a single spectrometer peak center (with an initial offset to force the coarse peak scan), and send me the log window output to examine?

I ran a highest intensity peaking and cannot reproduce your issue:

1. I acquired a peak scan for Mo La on Mo metal (20 keV, 100 nA) and get 68834 as the peak center as seen here:



2. I then detuned the spectrometer by specifying a peak center of 61960 and ran a peak center. The fine scan ran like this:



3. The fine scan failed (too close to edge of scan), so it automatically ran a coarse scan as seen here:



4. Note that it found the proper peak center of 61833. The 2nd fine scan then ran automatically as seen here:



So something must be wrong with your config or something as I do not see a problem...?  Or perhaps a mechanical issue?

[Probeman]

Hi Mike,
Just to be sure I ran a test this time on 4 spectrometers and setting the on-peak positions to a large offset on the low side and here is the coarse scan:



The 2nd fine scan then ran properly as seen here on our SX100:



I'm suspecting a mechanical problem on your spectrometer(s).  Please let us know what you find out.

One final question: are your spectrometers scanning from high to low or low to high?   I think JEOL spectrometers behave better when scanning from low to high so that the spectrometer motor is pushing against gravity...   see this topic:

http://probesoftware.com/smf/index.php?topic=451.0
john