Geo,

I can’t make out the fuzzy photo of the disks. Are these Th 230 disks calibrated ?SS plated with the dpm value on the label? What activity.? Are they plated over the entire surface or just a spot?

I use a plated Th 230 1” 11.700 dpm and a 2” 16,300 dpm set for doing radon counting to determine alpha counter efficiency and for the alpha spec cal.? I never thought to try an X-ray count on them.? Nice!

Dud

?

From: [email protected] [mailto:[email protected]] On Behalf Of GEOelectronics@...
Sent: Tuesday, December 24, 2019 9:46 AM
To: [email protected]
Subject: Re: [XRF] Looking at 16.300 dpm. ionium) discs are much more efficient than the 2" disc on both the Amptek detectors. Makes sense, they are nearly perfectly matched in size, with all the contents concentrated in a smaller area.

Radium-226 La,Lb, Lg are standing out.

Besides those, there is an expected 67.67 keV Gamma Ray, and an unexpected ~59.4 keV
peak. These two also? line up well with tungsten Ka-Kb. Gold would be expected, but not tungsten. ??

An XRF of the back of the metal disc showed the usual iron and chromium expected in stainless steel, no sign of any of the other rays 9(elf shielding)



Pics and .mca attached

Geo

I'm getting loopy, and will correct that after a nap.

Geo

----- Original Message -----
From: Dude <dfemer@...>
To: [email protected]
Sent: Mon, 23 Dec 2019 23:57:59 -0500 (EST)
Subject: Re: [XRF] Looking at Radium-226 from a rare perspective.

It’s a Th-230 disk decaying to Ra-226.?? You’re seeing the Ra x-ray
La . Lb, and Lg1. I don’t see the K’s he was mentioning.

Dud

?

From: [email protected]
[mailto:[email protected]] On Behalf Of Charles David Young
Sent: Monday, December 23, 2019 6:15 PM
To: [email protected]
Subject: Re: [XRF] Looking at Radium-226 from a rare perspective.

?

Not sure what we are looking at here.

?

Charles

?

On Mon, Dec 23, 2019 at 3:59 PM <GEOelectronics@...>
wrote:

This low energy gamma ray scan was done using an Amptek CdTe
detector, run for 2Hrs.


We are looking at Ra-226 being created in an environment devoid of peaks from
both Uranium parents, and Radium lower daughters.


The X-Ray energies are natural radiation from Ra-226 at the instant of its
creation. We see Ka, Kb and La peaks.?


This is part of a larger project to calibrate one unknown DPM calibration
against two known sources.


Enjoy.

Charles can you do a comparison out to past the 185 cutoff. The 185 cut off is what one would expect for a uranium only composition. The tails would indicate some self shielding.? Looks good for a natural

Dud

?

From: [email protected] [mailto:[email protected]] On Behalf Of Charles David Young
Sent: Monday, December 23, 2019 12:52 PM
To: [email protected]
Subject: Re: [XRF] Mineral identification in rocks that are also radioactive using various radiometric techniques.

?

I guess that accounts for most of those extra peaks in the Am X 8 scans.

?

Here is the U acetate compared to the liebigite.? They have basically the same peaks.

?

On Mon, Dec 23, 2019 at 12:58 PM <GEOelectronics@...> wrote:

Yes there is a test scan posted? with the exciter (Am X 8 pellets) and only an aluminum target. That post mentions possible background subtraction using that data Charles.

?

There is lead, brass (Cu +Zn) Iron and palladium in the exciter.

?

George?

This low energy gamma ray scan was done using an Amptek CdTe detector, run for 2Hrs.

We are looking at Ra-226 being created in an environment devoid of peaks from both Uranium parents, and Radium lower daughters.

The X-Ray energies are natural radiation from Ra-226 at the instant of its creation. We see Ka, Kb and La peaks.?

This is part of a larger project to calibrate one unknown DPM calibration against two known sources.

Enjoy.

W is not the normal substitution but does occur often enough. It is also a path finder element for the Coltan type materials.

Note the common W La,b shoulder associated with ?the Ta La,b in the attached files.? Take a look at the Colorado Linear vs Log plot.? A ?linear scale shows relative counts so it’s obvious what the ?higher abundance ?elements are. The log plot emphasizes the small subtle features that are missed if you are just looking at the linear. One does a pretty picture the other one has information.

?

His paper is preliminary and he’s trying to make a case for a better picture of substitution based classification as to what’s going to fit where in the coordination centers.? ?Identification, much less classification, of the ?Niobium Tantalates have never been really easy to do in trying to separate the euxenite – polycrase series which depends on the Fe Nb, Ta, And Ti concentrations. It seems simpler to just use ?the (Nb+Ta)/Ti ratios to classify it.? No one really seems to know what is what and opinions differ, mine included

Dud

?

From: [email protected] [mailto:[email protected]] On Behalf Of Charles David Young
Sent: Monday, December 23, 2019 5:27 AM
To: [email protected]; Mike Loughlin
Subject: Re: [XRF] Mineral identification in rocks that are also radioactive using various radiometric techniques.

?

I found a very interesting article about the classification of samarskite minerals (see attached).? I don't understand much of it but in the conclusion it mentions that Nb can be substituted by Ta, Ti, and W in various ways.? So I went back and looked at our CdTe scan and sure enough there is a W peak that I had not noticed before (see attached). So I guess this really could be samarskite by either mindat definition:

?

YFe³⁺Nb₂O₈

previously formulated as (Y,Fe³⁺,Fe²⁺,U,Th,Ca)₂(Nb,Ta)₂O₈ (IMA proposal 19-J)

?

Charles

?

Yes I did look under filtered UV briefly through the opened lid. Not impressed with its fluorescence.

Nothing like Autunite or Willamite for example.

Geo