Re: Bi Ka1/Ka2 bifurcation
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Why rush?? This is a hobby and learn as we go.....? I have more projects than I will ever get to by the time I push up daisies.? In retirement, slow is quite appropriate, at least for me.?
Dave - W?LEV
Nothing new, the second CdTe is the newestr AXR series is all. In a XR-100T head with preamp. It's been on the shelf waiting since maybe 2017, and has it's own power supply/controller, an analog PX2 type (the one we've been using is a newer digital PX4 type PS-MCA....¡. Some of the other silicon detectors go back way more than a decade- Alpha, Beta particle detectors, vacuum jigs, NIM modules and so on....all waiting their turn on the bench..
I might be slow, but methodical......
Geo
----- Original Message ----- From: Dude < dfemer@...> To: [email protected]Sent: Thu, 26 Dec 2019 13:38:05 -0500 (EST) Subject: Re: [XRF] Bi Ka1/Ka2 bifurcation
¡°¡±õ
would have had to do this anyway when the brand new?sensor head on the
shelf comes into service.¡±¡ ? ?What
new sensor on the shelf? ?whatta ya got now? Dud ? ? ? Very
good Charles. I have learned new things too thanks to Dudley. The
"Ll" line is not in my X-Ray Data book or XRF charts at all, but the
internet served it up, although you would probably never find it unless
specifically looking and had a name for it already. Thanks again for that Dud!
- Maybe there is an online lookup database on RadPro, NIST or other site? Yesterday
I spent testing CdTe sensor parameters like Peaking Time and pulse width. This
was tedious but productive and the results after many, many tests? is a
formula for best low-end resolution, and another one for fastest throughput in
the mid energy areas. Both give the clear 5.9 keV Mn line (from Fe-55 source)
with the lower noise completely eradicated from view. This alone makes for
better scans and the deadtime is reduced to zero because? the count rate
is a low figure. Beyond
the immediate need for basic operator knowledge, I would have had to do this
anyway when the brand new?sensor head on the shelf comes into service. ?After
applying the graded shield, then deriving the parameter formulae, a series of
tests were done on your Betafite sample, at different channel numbers-
512/1024/2048/4196/8192 could be studied. We will then standardize on one of
those. Both
1024 and 2048 channels give enough discreet peaks in the 16-17 keV area that
16.61keV Nb Ka peak can easily be picked out from the plethora of Uranium decay
series upper daughters' L shell lines. Gotta say though, it really doesn't look
promising for positive Nb ID.? Likewise
XRF with an isotopic source returns too many peaks in that region. That leaves
X-Ray tube XRF as the last best. I need to reevaluate those for the Nb lines
too, as some may have been misidentified back then.? Fortunately
we already have such scans from the 2013 series using the
Silicon-Drift-Detector 1-2-3. - I
won't post the mine or prospect location identification for privacy. We
can all probably recognize that as originally thought, for heavy REEs and
Trans-Lanthanide element identification a? low power microfocus 80 to 90
kVp X-Ray tube with a non interfering target (Cu?) with a CdTe detector would
be as good as it gets with today's XRF technologies. By
the way, shielding is a MUST HAVE.? That little sensor can Gamma Spec a $4
smoke detector, in the original unopened store packaging, at 1 or even 2 feet
away. Amazing and unexpected. I
had always wondered about the apparent bifurcation of the "Pb" peak
around 75.? Based on the CdTe scans that George has done recently we now
know that it is actually Bi Ka1/Ka2. The little bumps on the peak can be
aligned precisely.? They show up early in the run so that the energy
trimmer can be adjusted if necessary to account for temperature drift. Regarding
the consistent Y/Nb bump on these scans it is still uncertain whether the Nb
contribution is actually all or partially due to ThLb, even with the Si-PIN
scans.? Oh well.
-- Dave - W?LEV
Just Let Darwin WorkJust Think
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