Welcome to the XRF Wiki. This Wiki is a repository of information contributed by members of [email protected]. Members can view and edit the pages. The pages are currently not viewable by the public. The pages below represent a rough overview of the technology and techniques associated with X-Ray Florescence Spectroscopy as well as serving as a place for members to organize the spectra that they have contributed to the forum.?
As a starting point, the pages will be populated by information taken from member posts from the past few years - with references/attribution. Perhaps in time, these pages can be edited by members to make them more complete and less choppy. Members can also edit this page, making the structure of the content more organized.?
Pages can contain information about a particular topic, links to relevant resources (such as manuals, research papers, etc.), links to relevant forum discussions on the topic, book titles, or anything that might be useful.
What follows is very much a work in progress.
?
Adding to the Wiki
For those unfamiliar with the Wiki phenomenon, it is basically a user editable encyclopedia. The idea is that there are pages with different articles, which the user can read and also choose to edit if desired. If a piece of information is incorrect, a link outdated, or the presentation choppy or unclear, the user can just click "Edit Page" at the bottom and then fix the mistake. There is also a "Page History," so if you a user were to make a mistake or maliciously destroy a page (which wouldn't happen here) an editor can come along and restore the page to a previous version.?
If you have used MediaWiki (the engine that runs behind the scene of Wikipedia.org) you will be familiar with a certain style of creating an article. There are tags that one uses to change the formatting of the parts of the article. The Wiki on Groups.io uses a different background engine and so the standard MediaWiki syntax does not apply here. Rather, the page is edited using the same tools as one would use to compose a message on the forums. If you are a programmer or someone who likes using the tagged syntax directly, you can access the underlying page source code, be activating the advanced editing toolbar (the icon with three lines on the far right of the basic toolbar) and then clicking on the source code icon <> on the far right of the Advance Editing Toolbar. You will immediately notice that the underlying source code is HTML. Most things can be done just by using the various icons, but advanced features like table can only be implemented by manually writing the source code. (Although there are website available that will generate the source code for you through a graphical interface.)
This section describes the hardware used for XRF. We will describe the basic theory of operation of each stage in the processing tool chain and then present different commercial systems that are available as these systems are often integrated together.
[Editor note: General theory needs to be in an independent page separate from specific manufacturer information.
[Editor note - question: Should this be arranged by category, e.g detectors, preamps, etc or by manufacturer with the manufacturers product line on one page. Perhaps it's best to put a list of products with theory but the details of the products on a manufacture page...]
Detectors?- what's available, theory of operation, tradeoffs
Detector Cooling?- keeping detectors cool to avoid thermal noise and keeping the TEC from overheating
Preamps?- theory of operation, brief summary of what out there (and what not to do - such as trying to use a PMT preamp for a SiPIN diode...)
Pulse Processing Theory - high level overview of the stages of going from detector pulse to channel peaks on the computer
Commercial Systems - many commercial systems are integrated so it seems to make sense to present, for example all Amptek products together. [question: are their other affordable integrated systems besides Amptek?]
Hey
Dud, it is due to the ionic radius and crystal structure that this occurs.
Monazite is monoclinic and incorporates the LHEE, xenotime is tetragonal and
incorporates the HREE; both are phosphates. Zircon is a silicate and does not
incorporate HREE as much. There are at least two generations of zircon at
Petaca, and the first is poorer in REE. Pegmatites crystallize very quickly,
with late stage fluids corroding the first crystallized minerals. Real common
in these systems.?
Zircon HREE’s are interesting. Why do the heavies kick up in
the xenotime. ?Are there other zircons in the area that still hold the
HREE without any exsolution and at what concentration? ?How many episodes
of mineralization have these materials been through or is it all one unaltered
emplacement?
Here
are a couple of examples of how messy these minerals can be. The zircon from
the Coats is a variety called cyrtolite. If you look at the photos at the
bottom of the sheet you can see how xenotime is shot through the zircon; these
minerals are chemically different but structurally the same. As the zircon
crystallized, the xenotime exsolved. Next example is a very strange powdery
looking thorite. The normally dark glassy thorite has been replaced by xenotime
at a late stage, hence an odd altered white thorite that is about 15% REE. Note
how high Dy is in these analyses. Beam sizes varied from 3 to 20 microns. Late
stage xenotime alteration of minerals is very common in the district, and these
types of alteration and exsolution examples are common in many rare mineral
districts.
I would venture to say precise quantitative analysis is beyond the
reach of the professionals as well. For a simple matrix it works fine but for a
complicated matrix like rocks and junk it doesn’t and varies
wildly.? A ?SEM Micro probe properly calibrated is great, but a wide
beam on a target leaves a lot to be desired as you’ll get a mix of
interferences. Then there’s the software, some good, some bad and none
doing everything well and all are complicated to set up. ?Believe nothing,
verify everything and use it as an anomaly finder, then send it out for a real
ICP/MS analysis.
Soils is FP the other is a element cal. ?Soils has 3 beams
with filters at 50, 40 and 10 Kv Mining uses 50 and 10 Kv beams. The new
software is called Geochem and you don’t need to switch between the
modes. It’s expensive though.? I mostly use soils mode as I’m
looking for ppm anomalies.
?
A direct inter-comparison is not going to work very well unlike
gamma spec where the target is the source. In the XRF world we provide the
source which is going to be very different between everyone’s setup, beam
size, ?intensity and to a lesser extent detector characteristics.
?
I’m still looking for a CdTe rig . I have a 60kV microfocus
system I’d like to get running with it. I can use the LE ?HPGe
detectors but a CdTe will have better resolution and no LN2 issues
"Based
on the reported percentages the assay you are looking at was done using the
Soils mode which is used when looking at PPM level concentrations. The Soils
mode will well over report percent level concentrations? For samples with
percent grade material they would be shot with the Mining Plus mode."
?
I
agree that precise quantitative analysis is beyond the reach of our amateur
efforts at the moment. My first question is what is the difference between
SOILS mode and Mining Mode? Or perhaps I should ask WHERE is the difference? Is
it a scanning technique or is it all in software?
?
The
price of FP software has declined by about 50% already, but that took some
years to happen. Meantime I think we can all agree that direct comparison to a
known assayed mineral is a legitimate goal, as long as the sensors are the same
type?
?
That's
how I do uranium ore %, Cs-137 in soil,? and radium sample estimate , by
direct comparison with calibrated samples.
?
On
another thread, has anyone else anywhere else reported getting one of these
DP-5 processors up and running? It seems that maybe 20 or so of them have actually
been sold, maybe a few more.
?
Geo
?
-----
Original Message -----
From: Charles David Young <charlesdavidyoung@...>
To: [email protected]
Cc: Mike Loughlin <loughlin3@...>, Steve Dubyk
<sdubyk@...>, Frank Roberts <froberts@...>
Sent: Sat, 18 Jan 2020 13:21:26 -0500 (EST)
Subject: Re: [XRF] XRF - comparing Dud's with my Si-PIN
?
So
qualitatively the results from both XRFs seem to be similar.? I will be
looking at other specimens that you analyzed as well to see if they jive with
my setup.
?
So
what about the
FeSi escape vs TiKa1 issue?? Attached is a closeup of that region for the
TMG columbite (was samarskite Tub #2).? It sure seems like the
TiKa1 lines up better and it would be consistent with the Ti that you detected.
?
Charles
?
On
Sat, Jan 18, 2020 at 10:27 AM Dude <dfemer@...> wrote:
Charles,
Based on the reported percentages the assay you are looking at was
done using the Soils mode which is used when looking at PPM level
concentrations.
The Soils mode will well over report percent level concentrations? For
samples
with percent grade material they would be shot with the Mining Plus mode.?
See
if we shot that sample with both modes and use the Mining Plus mode to try a
cross calibrate with.? It’s doubtful that you’ll get a very
good cross cal as its
dependent on the element , matrix effects and detector efficiency over energy
as well as detector / x-ray geometry and x-ray flux.?
Cals are done using the Fundamental Parameter approach or by
running each element using a calibration curve.? A cal curve can be built
using
an element oxide and blending it down to PPM levels. That curve is still
dependent on distance of the target to the detector / X-ray geometry (also air
temp and moisture content and air density if you want to get picky) but most
importantly is the x-ray flux and beam filtering.? For your case you would
have
to normalize it to the Am-241 signal.? The system needs to have a fixed
ROI for
each element and you would use the baseline corrected area in that ROI as the
measured parameter. Complicating that are matrix effects where any other peaks
that
are intruding in that ROI must be de-convolved from it and the area corrected
for it. A Gaussian correction could be used The most important thing you need
to do is get a handle on the detector/X-ray/ target geometry. It must be the
same all the time. The beam angle to the target and the detector should be
changed from your dual illumination set up to a single beam path and keep the
angle around 30 deg or so to minimize backscatter.
Quantitative gamma ray spectroscopy is much simpler compared to
quantitative XRF and I never trust my XRF reported values without a great deal
of skepticism and review
Dud
?
?
From:[email protected]
[mailto:[email protected]] On
Behalf Of Charles David Young Sent: Saturday, January 18, 2020 5:45 AM To:[email protected];
Mike Loughlin; Steve Dubyk; Frank Roberts Subject: [XRF] XRF - comparing Dud's with my Si-PIN
?
Nearly 2 years ago (5/23/18) Dud
was kind enough to shoot
some of my specimens with his XRF "gun", which has a pinpoint xray
source.? Several of my rocks were found in the rubble piles of the local
rock shop "Tucson Mineral and Gem World", which has been open for
about 60 years.? One piece is large and ugly:
?
?
Looking at my results (blue
scan) the Nb peak is off the
charts!? Even more significant is that Dud's results show the same thing:
?
Nb 101.88%
Fe 35.76%
Ta 15.4%
Mn 2.54%
Y 0.279%
?
Comparing these percentages to
the relative heights of the
same peaks on my scan one finds similar proportions.? It is very
satisfying to know that my results largely corroborate those of Dud's.
?
Also plotted is a samarskite
from Little Patsy.? It has
a relatively high Y component.
From:[email protected]
[mailto:[email protected]] On Behalf Of Charles David Young Sent: Monday, January 20, 2020 6:14 PM To:[email protected] Cc: Mike Loughlin; Steve Dubyk Subject: Re: [XRF] White Signal bassetite
?
Here it is again.
?
On Mon, Jan 20, 2020 at 6:58 PM Dude <dfemer@...> wrote:
Send
the mca file
Dud
From:[email protected] [mailto:[email protected]] On Behalf Of Charles
David Young Sent: Monday, January 20, 2020 2:22 PM To:[email protected];
Mike Loughlin; Steve Dubyk Subject: [XRF] White Signal bassetite
?
This
is a scan that ran for 1 1/2 days using Am241 to excite.? It has a lot of
stuff in it and I will need everybody's help to interpret it (i.e. Dud).?
One complicating factor is that even with the Am241 the count rate was quite
low.? This causes the Am241 Np peaks (along with Au and Ag) to appear so
they have to be sorted out.
?
Here
are my notes in the comment box:
?
bassetite?
White Signal
贵别2+(鲍翱2)2(笔翱4)2·10贬2翱
main elements identified:
Fe Pb Rb Y Sn Te Cs Ba Ce
RbKa1 could be ULa1&2
YKa1 could be RbKb1
NpLb2 seems too big and could contain YKb1
On Mon, Jan 20, 2020 at 6:58 PM Dude <dfemer@...> wrote:
Send the mca file
Dud
From:[email protected]
[mailto:[email protected]] On Behalf Of Charles David Young Sent: Monday, January 20, 2020 2:22 PM To:[email protected]; Mike Loughlin; Steve Dubyk Subject: [XRF] White Signal bassetite
?
This is a scan that ran for 1 1/2 days using Am241 to
excite.? It has a lot of stuff in it and I will need everybody's help to
interpret it (i.e. Dud).? One complicating factor is that even with the
Am241 the count rate was quite low.? This causes the Am241 Np peaks (along
with Au and Ag) to appear so they have to be sorted out.
?
Here are my notes in the comment box:
?
bassetite? White Signal
贵别2+(鲍翱2)2(笔翱4)2·10贬2翱
main elements identified:
Fe Pb Rb Y Sn Te Cs Ba Ce
RbKa1 could be ULa1&2
YKa1 could be RbKb1
NpLb2 seems too big and could contain YKb1
Hey Dud, it is due to the ionic radius and crystal structure that this occurs. Monazite is monoclinic and incorporates the LHEE, xenotime is tetragonal and incorporates the HREE; both are phosphates. Zircon is a silicate and does not incorporate HREE
as much. There are at least two generations of zircon at Petaca, and the first is poorer in REE. Pegmatites crystallize very quickly, with late stage fluids corroding the first crystallized minerals. Real common in these systems.?
Zircon HREE’s are interesting. Why do the heavies kick up in the xenotime. ?Are there other zircons in the area that still hold the HREE without any exsolution and at what concentration?
?How many episodes of mineralization have these materials been through or is it all one unaltered emplacement?
Here are a couple of examples of how messy these minerals can be. The zircon from the Coats is a variety called cyrtolite. If you look at the photos at the bottom of the sheet you can see how xenotime
is shot through the zircon; these minerals are chemically different but structurally the same. As the zircon crystallized, the xenotime exsolved. Next example is a very strange powdery looking thorite. The normally dark glassy thorite has been replaced by
xenotime at a late stage, hence an odd altered white thorite that is about 15% REE. Note how high Dy is in these analyses. Beam sizes varied from 3 to 20 microns. Late stage xenotime alteration of minerals is very common in the district, and these types of
alteration and exsolution examples are common in many rare mineral districts.
I would venture to say precise quantitative analysis is beyond the reach of the professionals as well. For a simple matrix it works fine but for a complicated matrix like rocks
and junk it doesn’t and varies wildly.? A ?SEM Micro probe properly calibrated is great, but a wide beam on a target leaves a lot to be desired as you’ll get a mix of interferences. Then there’s the software, some good, some bad and none doing everything well
and all are complicated to set up. ?Believe nothing, verify everything and use it as an anomaly finder, then send it out for a real ICP/MS analysis.
Soils is FP the other is a element cal. ?Soils has 3 beams with filters at 50, 40 and 10 Kv Mining uses 50 and 10 Kv beams. The new software is called Geochem and you don’t need
to switch between the modes. It’s expensive though.? I mostly use soils mode as I’m looking for ppm anomalies.
?
A direct inter-comparison is not going to work very well unlike gamma spec where the target is the source. In the XRF world we provide the source which is going to be very different
between everyone’s setup, beam size, ?intensity and to a lesser extent detector characteristics.
?
I’m still looking for a CdTe rig . I have a 60kV microfocus system I’d like to get running with it. I can use the LE ?HPGe detectors but a CdTe will have better resolution and no
LN2 issues
"Based on the reported percentages the assay you are looking at was done using the Soils mode which is used when
looking at PPM level concentrations. The Soils mode will well over report percent level concentrations? For samples with percent grade material they would be shot with the Mining Plus mode."
?
I agree that precise quantitative analysis is beyond the reach of our amateur efforts at the moment. My first question is what is the difference between SOILS mode and Mining Mode? Or perhaps I should
ask WHERE is the difference? Is it a scanning technique or is it all in software?
?
The price of FP software has declined by about 50% already, but that took some years to happen. Meantime I think we can all agree that direct comparison to a known assayed mineral is a legitimate goal,
as long as the sensors are the same type?
?
That's how I do uranium ore %, Cs-137 in soil,? and radium sample estimate , by direct comparison with calibrated samples.
?
On another thread, has anyone else anywhere else reported getting one of these DP-5 processors up and running? It seems that maybe 20 or so of them have actually been sold, maybe a few more.
?
Geo
?
----- Original Message -----
From: Charles David Young <charlesdavidyoung@...>
To: [email protected]
Cc: Mike Loughlin <loughlin3@...>, Steve Dubyk <sdubyk@...>, Frank Roberts <froberts@...>
Sent: Sat, 18 Jan 2020 13:21:26 -0500 (EST)
Subject: Re: [XRF] XRF - comparing Dud's with my Si-PIN
?
So qualitatively the results from both XRFs seem to be similar.? I will be looking at other specimens that you analyzed as well to see if they jive with my setup.
?
So what about the
FeSi escape vs TiKa1 issue?? Attached is a closeup of that region for the TMG columbite (was samarskite Tub #2).? It sure seems like the
TiKa1 lines up better and it would be consistent with the Ti that you detected.
?
Charles
?
On Sat, Jan 18, 2020 at 10:27 AM Dude <dfemer@...> wrote:
Charles,
Based on the reported percentages the assay you are looking at was
done using the Soils mode which is used when looking at PPM level concentrations.
The Soils mode will well over report percent level concentrations? For samples
with percent grade material they would be shot with the Mining Plus mode.? See
if we shot that sample with both modes and use the Mining Plus mode to try a
cross calibrate with.? It’s doubtful that you’ll get a very good cross cal as its
dependent on the element , matrix effects and detector efficiency over energy
as well as detector / x-ray geometry and x-ray flux.?
Cals are done using the Fundamental Parameter approach or by
running each element using a calibration curve.? A cal curve can be built using
an element oxide and blending it down to PPM levels. That curve is still
dependent on distance of the target to the detector / X-ray geometry (also air
temp and moisture content and air density if you want to get picky) but most
importantly is the x-ray flux and beam filtering.? For your case you would have
to normalize it to the Am-241 signal.? The system needs to have a fixed ROI for
each element and you would use the baseline corrected area in that ROI as the
measured parameter. Complicating that are matrix effects where any other peaks that
are intruding in that ROI must be de-convolved from it and the area corrected
for it. A Gaussian correction could be used The most important thing you need
to do is get a handle on the detector/X-ray/ target geometry. It must be the
same all the time. The beam angle to the target and the detector should be
changed from your dual illumination set up to a single beam path and keep the
angle around 30 deg or so to minimize backscatter.
Quantitative gamma ray spectroscopy is much simpler compared to
quantitative XRF and I never trust my XRF reported values without a great deal
of skepticism and review
Dud
?
?
From:[email protected]
[mailto:[email protected]] On Behalf Of
Charles David Young Sent: Saturday, January 18, 2020 5:45 AM To:[email protected]; Mike Loughlin; Steve Dubyk; Frank Roberts Subject: [XRF] XRF - comparing Dud's with my Si-PIN
?
Nearly 2 years ago (5/23/18) Dud was kind enough to shoot
some of my specimens with his XRF "gun", which has a pinpoint xray
source.? Several of my rocks were found in the rubble piles of the local
rock shop "Tucson Mineral and Gem World", which has been open for
about 60 years.? One piece is large and ugly:
?
?
Looking at my results (blue scan) the Nb peak is off the
charts!? Even more significant is that Dud's results show the same thing:
?
Nb 101.88%
Fe 35.76%
Ta 15.4%
Mn 2.54%
Y 0.279%
?
Comparing these percentages to the relative heights of the
same peaks on my scan one finds similar proportions.? It is very
satisfying to know that my results largely corroborate those of Dud's.
?
Also plotted is a samarskite from Little Patsy.? It has
a relatively high Y component.
From:[email protected]
[mailto:[email protected]] On Behalf Of Charles David Young Sent: Monday, January 20, 2020 2:22 PM To:[email protected]; Mike Loughlin; Steve Dubyk Subject: [XRF] White Signal bassetite
?
This is a scan that ran for 1 1/2 days using Am241 to
excite.? It has a lot of stuff in it and I will need everybody's help to
interpret it (i.e. Dud).? One complicating factor is that even with the
Am241 the count rate was quite low.? This causes the Am241 Np peaks (along
with Au and Ag) to appear so they have to be sorted out.
?
Here are my notes in the comment box:
?
bassetite? White Signal
贵别2+(鲍翱2)2(笔翱4)2·10贬2翱
main elements identified:
Fe Pb Rb Y Sn Te Cs Ba Ce
RbKa1 could be ULa1&2
YKa1 could be RbKb1
NpLb2 seems too big and could contain YKb1
El El lun, ene. 20, 2020 a la(s) 3:21 p.?m., Charles David Young <charlesdavidyoung@...> 别蝉肠谤颈产颈ó:
This is a scan that ran for 1 1/2 days using Am241 to excite.? It has a lot of stuff in it and I will need everybody's help to interpret it (i.e. Dud).? One complicating factor is that even with the Am241 the count rate was quite low.? This causes the Am241 Np peaks (along with Au and Ag) to appear so they have to be sorted out.
Here are my notes in the comment box:
bassetite? White Signal 贵别2+(鲍翱2)2(笔翱4)2·10贬2翱
main elements identified: Fe Pb Rb Y Sn Te Cs Ba Ce
RbKa1 could be ULa1&2 YKa1 could be RbKb1 NpLb2 seems too big and could contain YKb1
El El lun, ene. 20, 2020 a la(s) 3:21 p.?m., Charles David Young <charlesdavidyoung@...> 别蝉肠谤颈产颈ó:
This is a scan that ran for 1 1/2 days using Am241 to excite.? It has a lot of stuff in it and I will need everybody's help to interpret it (i.e. Dud).? One complicating factor is that even with the Am241 the count rate was quite low.? This causes the Am241 Np peaks (along with Au and Ag) to appear so they have to be sorted out.
Here are my notes in the comment box:
bassetite? White Signal 贵别2+(鲍翱2)2(笔翱4)2·10贬2翱
main elements identified: Fe Pb Rb Y Sn Te Cs Ba Ce
RbKa1 could be ULa1&2 YKa1 could be RbKb1 NpLb2 seems too big and could contain YKb1
This is a scan that ran for 1 1/2 days using Am241 to excite.? It has a lot of stuff in it and I will need everybody's help to interpret it (i.e. Dud).? One complicating factor is that even with the Am241 the count rate was quite low.? This causes the Am241 Np peaks (along with Au and Ag) to appear so they have to be sorted out.
Here are my notes in the comment box:
bassetite? White Signal 贵别2+(鲍翱2)2(笔翱4)2·10贬2翱
main elements identified: Fe Pb Rb Y Sn Te Cs Ba Ce
RbKa1 could be ULa1&2 YKa1 could be RbKb1 NpLb2 seems too big and could contain YKb1
This is the little portable exciter. It is a mini-X-Ray tube made by Kevex, controlled by a LIXI power supply. When coupled with the LIXI X-Ray Intensifier Viewer, it used as a C-Arm, to take pictures, videos or to simply look inside things optically by direct real time view. In the C-Arm mode this tube can provide up to 50 kVp and 200 uA. When used for XRF it must be throttled way, way back down- starting with the controls to limit the current to either 10 or 15 uA, then lead collimator with a 1mm hole in thick lead, then filters made of layers of aluminum sheeting. The HV itself is set to a value that just exceeds the K-edge of the elements being examined. Another method if the HV is not readily adjustable is to irradiate an intermediate target, say silver, then use the characteristic X-Rays from that target to illuminate the XRF from the main sample being tested. Geo
----- Original Message ----- From: Dude <dfemer@...> To: [email protected] Sent: Mon, 20 Jan 2020 12:14:32 -0500 (EST) Subject: [XRF] Currency XRF Quiz results
?
Sent: Sunday, January 19, 2020 11:19 AM To:[email protected] Subject: [XRF] Currency XRF Quiz
?
Here’s Geo’s 1958 copper nickel in log space.? What do ?we have here?
Anyone?, anyone? Beuller?... Beuller?
Dud
?
?
Since no one had a correct answer and undoubtedly the question will come up on any ?future final exams the answer is:
?
First peak is the Si escape peak at 6.3 keV from Cu Ka at ?8.05 keV (8.05 Ka – 1.74 Si Ka)
The next 3 peaks are the characteristic X-rays from Ni Ka1 at 7.48, Cu Ka1 at 8.05, and Cu Kb1 at 8.9 keV
The next set ?of peaks (first clue) looks just like the Ni and Cu characteristic x-ray complex.? It does that because it’s the sum peaks of the Ni and Cu due to the high count rate (46% dead time remember) and high concentrations.
The first peak at 15.6 keV is the coincident sum peak of? 8.05 keV Cu and the 7.52 keV Ni
The second peak at 16.1 is the sum peak of the 8.05 Cu and 8.05 Cu
The third peak at 16.9 is the sum peak of the 8.05 Cu and the 8.9 Cu.
?
Sum peaks are 2 photons arriving at the detector at the same time. That can be a Ka+Ka or Ka + Kb and a mix between high concentration elements as seen here. This can also be seen with coincident decay (i.e. Co-60) and in high concentration samples with a high count rate.. Keep the sample at a distance rather than close up (for an gamma spec sample not XRF). Keep your Dead time less than 10%.
?
The escape peaks occur when the Si in the detector absorbs some of the energy from an x-ray and produces a peak (Si Ka) 1.74 keV below the element’s ?Ka or La . You’ll see this in the lower Z elements or at high concentration.
Sent: Sunday, January 19,
2020 11:19 AM To:[email protected] Subject: [XRF] Currency XRF Quiz
?
Here’s Geo’s 1958 copper nickel in log space.? What do
?we have here?
Anyone?, anyone? Beuller?... Beuller?
Dud
?
?
Since no one had a correct answer and undoubtedly the question
will come up on any ?future final exams the answer is:
?
First peak is the Si escape peak at 6.3 keV from Cu Ka at
?8.05 keV (8.05 Ka – 1.74 Si Ka)
The next 3 peaks are the characteristic X-rays from Ni Ka1 at
7.48, Cu Ka1 at 8.05, and Cu Kb1 at 8.9 keV
The next set ?of peaks (first clue) looks just like the Ni
and Cu characteristic x-ray complex.? It does that because it’s the sum
peaks of the Ni and Cu due to the high count rate (46% dead time remember) and
high concentrations.
The first peak at 15.6 keV is the coincident sum peak of?
8.05 keV Cu and the 7.52 keV Ni
The second peak at 16.1 is the sum peak of the 8.05 Cu and 8.05 Cu
The third peak at 16.9 is the sum peak of the 8.05 Cu and the 8.9
Cu.
?
Sum peaks are 2 photons arriving at the detector at the same time.
That can be a Ka+Ka or Ka + Kb and a mix between high concentration elements as
seen here. This can also be seen with coincident decay (i.e. Co-60) and in high
concentration samples with a high count rate.. Keep the sample at a distance
rather than close up (for an gamma spec sample not XRF). Keep your Dead time
less than 10%.
?
The escape peaks occur when the Si in the detector absorbs some of
the energy from an x-ray and produces a peak (Si Ka) 1.74 keV below the
element’s ?Ka or La . You’ll see this in the lower Z elements or at high
concentration.
El El sáb, ene. 18, 2020 a la(s) 10:09 p.?m., Dude <dfemer@...> 别蝉肠谤颈产颈ó:
Steve,
Zircon HREE’s are interesting. Why do the heavies kick up in
the xenotime.? Are there other zircons in the area that still hold the
HREE without any exsolution and at what concentration?? How many episodes of
mineralization have these materials been through or is it all one unaltered
emplacement?
Here
are a couple of examples of how messy these minerals can be. The zircon from
the Coats is a variety called cyrtolite. If you look at the photos at the
bottom of the sheet you can see how xenotime is shot through the zircon; these
minerals are chemically different but structurally the same. As the zircon
crystallized, the xenotime exsolved. Next example is a very strange powdery
looking thorite. The normally dark glassy thorite has been replaced by xenotime
at a late stage, hence an odd altered white thorite that is about 15% REE. Note
how high Dy is in these analyses. Beam sizes varied from 3 to 20 microns. Late
stage xenotime alteration of minerals is very common in the district, and these
types of alteration and exsolution examples are common in many rare mineral
districts.
I would venture to say precise quantitative analysis is beyond the
reach of the professionals as well. For a simple matrix it works fine but for a
complicated matrix like rocks and junk it doesn’t and varies
wildly.? A ?SEM Micro probe properly calibrated is great, but a wide
beam on a target leaves a lot to be desired as you’ll get a mix of interferences.
Then there’s the software, some good, some bad and none doing everything
well and all are complicated to set up.? Believe nothing, verify
everything and use it as an anomaly finder, then send it out for a real ICP/MS
analysis.
Soils is FP the other is a element cal.? Soils has 3 beams
with filters at 50, 40 and 10 Kv Mining uses 50 and 10 Kv beams. The new
software is called Geochem and you don’t need to switch between the
modes. It’s expensive though.? I mostly use soils mode as I’m
looking for ppm anomalies.
?
A direct inter-comparison is not going to work very well unlike
gamma spec where the target is the source. In the XRF world we provide the
source which is going to be very different between everyone’s setup, beam
size, ?intensity and to a lesser extent detector characteristics.
?
I’m still looking for a CdTe rig . I have a 60kV microfocus
system I’d like to get running with it. I can use the LE ?HPGe
detectors but a CdTe will have better resolution and no LN2 issues
"Based
on the reported percentages the assay you are looking at was done using the
Soils mode which is used when looking at PPM level concentrations. The Soils
mode will well over report percent level concentrations? For samples with
percent grade material they would be shot with the Mining Plus mode."
?
I
agree that precise quantitative analysis is beyond the reach of our amateur
efforts at the moment. My first question is what is the difference between
SOILS mode and Mining Mode? Or perhaps I should ask WHERE is the difference? Is
it a scanning technique or is it all in software?
?
The
price of FP software has declined by about 50% already, but that took some
years to happen. Meantime I think we can all agree that direct comparison to a
known assayed mineral is a legitimate goal, as long as the sensors are the same
type?
?
That's
how I do uranium ore %, Cs-137 in soil,? and radium sample estimate , by
direct comparison with calibrated samples.
?
On
another thread, has anyone else anywhere else reported getting one of these
DP-5 processors up and running? It seems that maybe 20 or so of them have
actually been sold, maybe a few more.
So
qualitatively the results from both XRFs seem to be similar.? I will be
looking at other specimens that you analyzed as well to see if they jive with
my setup.
?
So
what about the
FeSi escape vs TiKa1 issue?? Attached is a closeup of that region for the
TMG columbite (was samarskite Tub #2).? It sure seems like the
TiKa1 lines up better and it would be consistent with the Ti that you detected.
?
Charles
?
On
Sat, Jan 18, 2020 at 10:27 AM Dude <dfemer@...> wrote:
Charles,
Based on the reported percentages the assay you are looking at was
done using the Soils mode which is used when looking at PPM level
concentrations.
The Soils mode will well over report percent level concentrations? For
samples
with percent grade material they would be shot with the Mining Plus mode.?
See
if we shot that sample with both modes and use the Mining Plus mode to try a
cross calibrate with.? It’s doubtful that you’ll get a very
good cross cal as its
dependent on the element , matrix effects and detector efficiency over energy
as well as detector / x-ray geometry and x-ray flux.?
Cals are done using the Fundamental Parameter approach or by
running each element using a calibration curve.? A cal curve can be built
using
an element oxide and blending it down to PPM levels. That curve is still
dependent on distance of the target to the detector / X-ray geometry (also air
temp and moisture content and air density if you want to get picky) but most
importantly is the x-ray flux and beam filtering.? For your case you would
have
to normalize it to the Am-241 signal.? The system needs to have a fixed
ROI for
each element and you would use the baseline corrected area in that ROI as the
measured parameter. Complicating that are matrix effects where any other peaks
that
are intruding in that ROI must be de-convolved from it and the area corrected
for it. A Gaussian correction could be used The most important thing you need
to do is get a handle on the detector/X-ray/ target geometry. It must be the
same all the time. The beam angle to the target and the detector should be
changed from your dual illumination set up to a single beam path and keep the
angle around 30 deg or so to minimize backscatter.
Quantitative gamma ray spectroscopy is much simpler compared to
quantitative XRF and I never trust my XRF reported values without a great deal
of skepticism and review
Dud
?
?
From:[email protected]
[mailto:[email protected]] On
Behalf Of Charles David Young Sent: Saturday, January 18, 2020 5:45 AM To:[email protected];
Mike Loughlin; Steve Dubyk; Frank Roberts Subject: [XRF] XRF - comparing Dud's with my Si-PIN
?
Nearly 2 years ago (5/23/18) Dud
was kind enough to shoot
some of my specimens with his XRF "gun", which has a pinpoint xray
source.? Several of my rocks were found in the rubble piles of the local
rock shop "Tucson Mineral and Gem World", which has been open for
about 60 years.? One piece is large and ugly:
?
?
Looking at my results (blue scan)
the Nb peak is off the
charts!? Even more significant is that Dud's results show the same thing:
?
Nb 101.88%
Fe 35.76%
Ta 15.4%
Mn 2.54%
Y 0.279%
?
Comparing these percentages to
the relative heights of the
same peaks on my scan one finds similar proportions.? It is very
satisfying to know that my results largely corroborate those of Dud's.
?
Also plotted is a samarskite from
Little Patsy.? It has
a relatively high Y component.
Yes I used collimator, filters and shielding. Pictures exist of all and will be posted as I flesh out the topics. I did these currency scans 6 years ago in my portable radlab in NV, and not really examined much until now....
----- Original Message ----- From: Dude <dfemer@...> To: [email protected] Sent: Sun, 19 Jan 2020 12:42:21 -0500 (EST) Subject: Re: [XRF] Currency XRF
Charles ,
He asked for 300 secs of live time which required ?623 secs of real time due to high count rate pile up . ?The count rate was way too high with a dead time of 46%. ?Dead time should be kept under 10% to preserve spectral shape and energy shift. ?Even using just 10ua of beam current really gets a strong signal. ?Compare his 200,000 count peak to your 50 count or so peaks after 31,000 secs. ?Flux rate ?sure helps.
See the info bar on the right- 300 seconds accumulated (live) time. Real time (clock time)= ~600 seconds due to deadtime. 10 microamps is about as low as one of these tubes can be adjusted to. I believe an X- Ray tube would eliminate your issues with looking for stable elements in radioactive rocks. You simply overwhelm the natural radiation with X-Ray induced characteristic X-Rays. Soon I will corroborate what 8 X Am-241 will do on silver, vs. several known Cd-109 radioisotopes that have aged- in other words compare artificially induced silver Ka with no more than 8 uCi Am, to a known amount of actual radioisotope.
Run the .mca file on the silver war nickel- expand the scale in the Cu Ka region.
This does not look to me like the :
56% copper
35% silver
9% manganese
claimed by online experts.
Truth be known in the early years of WW2, it was all hands on deck and something and elbows......
----- Original Message ----- From: Charles David Young <charlesdavidyoung@...> To: [email protected] Sent: Sun, 19 Jan 2020 12:02:11 -0500 (EST) Subject: Re: [XRF] Currency XRF
How long does it take to get those kind of counts?
El El dom, ene. 19, 2020 a la(s) 9:59 a.?m., <GEOelectronics@...> 别蝉肠谤颈产颈ó:
He asked for 300 secs of live time which required ?623 secs of
real time due to high count rate pile up . ?The count rate was way too high
with a dead time of 46%. ?Dead time should be kept under 10% to preserve
spectral shape and energy shift. ?Even using just 10ua of beam current really
gets a strong signal. ?Compare his 200,000 count peak to your 50 count or so peaks
after 31,000 secs. ?Flux rate ?sure helps.
