Re: OK Dude, how do we excite those RE's above 50 keV cleanly and how to detect it.
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My 50kV ?gun is limited to 50 kV due to the backscatter and the
FDA shielding issues. The SSD drops off pretty quickly at about 60 keV for the
photoelectric response unlike CdTe which can see the U Ka at 98 easily.? A Si
Pin is similar to the SSD in range but much poorer in resolution. ?Both depend
on the depletion depths and peaking time.? The problem is efficiency at the
high energies. I can see Sm with a 50 kV xray but it¡¯s got to be in the percent
range.? I have a Kevex 60 kV xray microfocus unit here but no detector other
than some ?low energy ?HPGe¡¯s to use with it. I had been toying with the idea
of picking up a Cd Te detector to play with.? A fast SSD would really help with
resolution.
U and Th La¡¯s are easy to see.
?The problem with the HREE is you have to look at the La ?and Lb¡¯s
which occur in the ?matrix of everything else and don¡¯t resolve well. Using the
Ka, Kb¡¯s requires a 50kV tube up to Pm. Above that you want to be about 10 -20
keV above the binding energy. U and Th occupy a fairly open region above the
mess below and are easily seen in the La and Lb range.
Rather than cooling down the HPGe detectors I look at the HREE
with a homebrew LIBS system which see everything.
I¡¯ll be looking in to a CdTe detector but I¡¯m sure I¡¯d also be
tempted to get a Fast SSD for the Kevex.
What are the specs on your SiPin? Window and SI thickness?? What
do you have for the CdTe setup?
Dud
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From: [email protected]
[mailto:[email protected]] On Bto the SDehalf Of GEOelectronics@...
Sent: Tuesday, October 22, 2019 3:50 PM
To: [email protected]
Subject: [XRF] OK Dude, how do we excite those RE's above 50 keV
clkeanly and how to detect it.
?
Does your SDD go above 50 keV?
The Si-Pin really falls off sharply, @59.5 is by no means blowing it away,
while the X-Rays are fantastic.
Over the winter I'll try to get the CdTe sensor online... but have to make a
set of cables first between power supply/shaping amp and sensor/preamp
head......it's supposed to be good from 5 to above 100 maybe even to 200, but
no microfocus exciter in that range....
Recently I accidentally ID'ed uranium by XRF- the rock was not labeled and I
didn't suspect it to be radioactive, but there were those U XRF lines right on
the button. Will try something with thorium soon.
Geo
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