are we talking about a 4.5 keV peak possibly being the Si escape peak of the 6.4 main peak here? I'll put it up and take a look too.
Geo
----- Original Message -----
From: Dude <dfemer@...>
To:
[email protected]Cc: 'Mike Loughlin' <loughlin3@...>
Sent: Wed, 11 Mar 2020 13:54:53 -0400 (EDT)
Subject: Re: [XRF] DppMCA vs Theremino
Charles,
The peak between your Fe esc and the Am label isn¡¯t La I eyeballed
and the centroid at 4.5 appears to be a Ti Ka. If the cal is off just a bit it
could be the Fe esc although it appears to be too large for that. What energy
is that Am tag? Is this miss-labeled?
Dud
?
?
George, here is the .mca that I used for this example and
will use to try and replicate the process with DppMCA.
?
On Sun, Mar 8, 2020 at 12:22 PM Dude <dfemer@...> wrote:
Charles,
I
assume this was slider cal¡¯d.? Why is Fe escape in the Am button? Or are
these 2 different buttons?? What Am energy is it? This is quick and dirty
but can still miss a lot of stuff.? You assumed ?Y, Nb and Zr but
didn¡¯t look any further at each individual peak to validate the assumption The
Fe Ka1 and weak Kb ?shows there is Fe there. The peak between the Am and
Fe esc looks like La la1. That would need to be confirmed with the higher
energy Ka which it doesn¡¯t look like you did or maybe you did, I can¡¯t tell
from the plots. The question is what would La be doing in a Fergusonite
/cyrtolite? Is it even there?? I understand using tabs for interferences
and a quick look but it¡¯s essential to look at everything on an individual peak
energy basis which will help or eliminate your hypothesis.
Thanks
for the nice run though I can see your method and approach.
dud
?
?
?
Based
on Dud's encouragement I will try and use DppMCA for analysis.? To be
clear, I tried it previously when I first got the Amptek system and got
discouraged.? I'll give it another try and document it in a subsequent
email.
First
though I wish to give a quick demo of how I use DppMCA for acquisition and
Theremino for analysis.? I will make it as simple as possible.? I
will both embed the images as well as attach them because some people have
better luck with one or the other.? If you download the attachments and
put them in a folder you can scroll through the images as I describe the steps.
The
target is a small specimen that has some nice little fergusonite crystals
associated with zircon cyrtolite.? Because it does not present the ideal
geometry it took an overnight run to collect the data.
Step
2: import into Theremino
I
modified Theremino to recognize the .mca format and import the data with no
processing other than to draw it on the screen using the available resolution.?
Step
3: turn on reference labels
Because
of the Am241 source and its shielding there are many peaks that I wish to be
aware of so that I can ignore them most of the time.? This creates some
temporary clutter but it allows me to quickly determine which peaks are really
of interest.
Step
4: zoom in on region of interest
It
is immediately apparent that there are 3 large peaks that don't align with any
of the reference peaks.? I zoom in on those to reduce the clutter.
Sometimes
we are not so lucky such as the case of Fe which is present in the Am241
button.? In this case I am pretty sure it is not a major element of the
specimen.? If the Fe peak were much larger I would assume differently.
Step
5: identify the Nb peak
I
use my mouse to double click on the largest peak.? The id label NbKa1
appears over that peak and the NbKa2 and NbKb1 labels appear at the same
time.? Having these labels toggle on and off as a set allows me to quickly
evaluate the validity of an id.? In this case all 3 peaks look reasonable
so I will assume with confidence that Nb is present in this mineral.
Step
5: identify the Zr peak
I
double click on the next highest peak.? Once again all 3 peaks align
nicely with Zr, even though the ZrKb1 label is a little obscured.? I'll
clean that up later.? Zr is definitely also present.
Step
6: identify the Y peak
I
double click on the last large peak and the Y identity labels appear.? The
YKa1 and YKa2 peaks line up precisely so this is also looking good.? The
YKb1 peak is a little more subtle because it is so close to the NbKa1 peak.?
They are so close in fact that when both Nb and Y are present their peaks add
together to make an extra large peak.? The presence of the YKb1 peak is
betrayed but the bulge on the right side.? Once again I can say with
confidence that Y is present.
Step
7: declutter and document
There
are no other major peaks of interest so I can turn off the reference labels and
document my results in the text box on the left.?
This
whole process took perhaps 2 or 3 minutes. Luckily I was able to identify all
the elements necessary to justify this mineral identity.? Typically there
are many other elements present and it can take a little longer.? If the
elements don't match the mineral formula very well further research is
sometimes necessary to clarify the id.
