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 If a piece of information is incorrect, a link outdated, or the presentation choppy or unclear, the user can just click "Edit Page" at the bottom and then fix the mistake.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?]
I agree, and we can't expect anything below ~2keV in air, but what this shows me is with a helium atmosphere, we could have a shot at down to 1.
?I tried propane (once) and it changed things, bit of course is not practical, just as hydrogen is not practical. Vacuum is best, but at this time it's not in the cards for me.
Charles have you considered XRD for your minerals? If so check out the Tel-X-Ometer unit. I have several of those waiting a turn in the counting room. The way XRD works baffles me but it seems to be a very popular mode for determining crystal structure and maybe oxidation states (?). No immediate plans to do so but have used the internal copper-target X-Ray source in it many times for other purposes. Switch selectable 20 / 30 kV at 80uA. These have an integral goniometer, and the ones I get usually have that part damaged by corrosion due to leaving salt crystals in it when stored (they are a college teaching tool).
----- Original Message ----- From: Charles David Young <charlesdavidyoung@...> To: XRF <[email protected]> Sent: Fri, 30 Oct 2020 10:53:09 -0400 (EDT) Subject: Re: FW: [XRF] 59.5keV spectrum cleanup
It just looks like noise to me.? I would have to see a lot more counts and reproducible runs to believe it.
Great idea on the reverse-osmosis water discharge!
Test everything!
Here's another great idea for collecting samples from water, a paper by?
"A Sensitive XRF Screening Method for Lead in Drinking Water"
Abstract
A novel method for quickly and quantitatively measuring aqueous lead in drinking water has been developed. A commercially available activated carbon felt has been found to effectively capture lead from tap water, and partnered with X-Ray fluorescence (XRF) spectrometry, it provides quantitative measurement of aqueous lead in drinking water. Specifically, for a 2-liter volume of tap water, the linear range of detection was found to be from 1 ¨C 150 ppb, encompassing the current EPA limit for lead in drinking water (15 ppb). To make a reproducible and easy to use method for filtering, a 2L bottle cap with a 1.25 cm diameter hole was used for filtering. Utilizing this filtration method, 75 solutions from 0 ppb to 150 ppb lead gave a 91% sensitivity, 97% specificity, and 93% accuracy and all the misclassified samples fell between 10 and 15 ppb. This method has also proved reliable for detecting calcium as well as several other divalent metals in drinking water including copper, zinc, iron, and manganese.
Note- She has tested all sorts of premade activated charcoal felt sheeting to find one that is inexpensive and yet performs very well for those heavy metals. I can send the paper by email but can't post it online.
----- Original Message ----- From: taray singh via groups.io <sukhjez@...> To: [email protected] Sent: Fri, 30 Oct 2020 10:14:27 -0400 (EDT) Subject: [XRF] Chinese water filter analysis
Hi guys I am interested in drinking water quality testing and most drinking water test kits are not accurate. They give positive readings on concentrated samples like sewage and not for trace elements in drinking water. So I wanted to try out this interesting Chinese? gadget. Search you tube for..?Water Electrolyzer (Quality Tester). The Most Dangerous Appliance Ever? Negative comments being dangerous? and a scam. I checked it out There are 2 pairs of electrodes A shiny aluminium and a dull? iron pair. Repeated usage caused the? iron to rust. Aluminium was confirmed? by exclusion being shiny,light,cheap and nondescript. My drinking water? sample is RO? waste water . This discharged RO waste water is about 4 times more concentrated than my tap water depending on machine cycling. Concentrated means more residue better than plain tap water for analysis. My 14 in 1test kit was basically negative? for heavy metals. I tested this RO concentrated with this Chinese toy. It produced a brownish residue as expected. Collected it and allowed it dry on cap and a tissue. This cap/tissue was analyzed with Xrf with Am241/Si pin detector. True enough like the you tubers described there is Fe from galvanic reactions. There appears to be Pb peak as well I need to repeat this test with a thicker sample? to confirm . Taray
Ok your 4.8us. Yes I ran that too for a long time.
Here's an expanded look at the lowest energy end of that scan, with pretty arrows to point out the lowest fully resolved peak (although there is another even below that one, but this one has clear on both sides and the sides go way down... The subject is very weakly radioactive, and that low peak may not have any real meaning, but now all the peaks except the odd 1 count hits are actual peaks from something, not electronics noise. Even the lowest thing visible has a top to it.
Thanks for that report Charles. Of the two, can you say what is the lowest peak that can be resolved and is there a difference between them?? My just finished overnight run using the Si-PIN on a weakly radioactive sample for Gamma Spec (not excited XRF) is resolving individual peaks down to less than 1.5 keV. In the Peaking Time topic thread I'll post that test @19.2us PT along with a nearly similar test done last February at 4.8us. The main difference between those seems to be both in the clarity and narrowness of the big peaks, and better performance at the lowest end going to the 19.2.
Today I'll try even longer peaking times, up to 32us just for the historical record.?
I think you've been using 32us and I can't fault your scans, that's for sure.
Geo
----- Original Message ----- From: Charles David Young <charlesdavidyoung@...> To: XRF <[email protected]> Sent: Fri, 30 Oct 2020 08:26:25 -0400 (EDT) Subject: Re: FW: [XRF] 59.5keV spectrum cleanup
I did 2 runs on a brannerite specimen.? One like normal (red) and the other with a paper adhesive label covering the buttons.? The proportions of the peaks pretty much look the same to me.
Charles
On Wed, Oct 28, 2020 at 11:30 AM Dude <dfemer@...> wrote:
Charles,
My mistake, I now see the problem you¡¯re using a log energy axis. That should always be linear, counts can be log, lin or sqr as appropriate.
Looking at the png you sent there is something seriously wrong on the low energy below 4 keV. Send the mca file for a look as it may just be a Theremino problem. For these low energies you¡¯ll want to keep the Np in there, but to pull these elements out you really need a high flux rate which the Am source isn¡¯t doing. Even with a tube the efficiencies are very poor and the counts are low making it hard to quantify. However, the Al Si, P, S, Ca and K ?are absolutely essential to determining the basic mineralogy types and every effort should be made to verify their presence.
To get the count times up readjust the gain to look only at the low energy range say from 10 on down and see ff that helps pull them out. Using a tight focused beam and close up to the target will also help concentrate the flux.
Dud
?
From:[email protected] [mailto:[email protected]] On Behalf Of Charles David Young Sent: Wednesday, October 28, 2020 8:12 AM To: XRF Subject: Re: FW: [XRF] 59.5keV spectrum cleanup
?
Geo,
?
I agree and I did not mean to dis this exercise, even if it turns out to be primarily academic.
?
When I get a chance I'll try the paper filter with a mineral like Brannerite (UTi2O6) to see how it affects the Ti peak at 4.5keV.? That is typically the lowest element that is essential to my application.? Other peaks like P, K, Ca would be nice but I have learned to live without them.? If we could somehow dig those out by an adjustment it would be great.
"The filter comes at a cost.? Am I reading it correctly that it reduced the input count to %25 of the non-filtered?? Do we need to wait 4x longer for equal counts when this is used as an exciter? "
?
All that is to be determined Charles. It well may be much worse than that, if the low energies in the beam are what's helping to dig out the low energy XRF signals we are looking for.
?
I agree about our perspective points of view too.?
?
You system is as ideal as can be for your main task, and your display program is an advancement in the area of display and identification, especially for the audience of that group. Now the photography meets the same standard too. No one has added all those dimensions in one place to the amateur mineral group before.? All for science' sake, and I applaud that.
?
For you and others I would recommend trying a paper filter over the exciter source, just to see.
?
The rest is for the X-Ray Physics and X-Ray Optics crowd. We now have an inexpensive but powerful tool in our toolbox that wasn't there 2 days ago.
The filter comes at a cost.? Am I reading it correctly that it reduced the input count to %25 of the non-filtered?? Do we need to wait 4x longer for equal counts when this is used as an exciter?? Was all that low energy activity that is filtered out detrimental or beneficial when the button is used to stimulate XRF in the target?
?
I come at this from a different perspective.? I use the Si-PIN with an Am241 exciter to identify minerals.? In my experience the XRF coming from the target is much stronger than the noise introduced by the Am241, which is mounted on a shield and facing away from the detector.? Attached is a scan of xenotime, which shows a large Y component as well as some U and Pb.? I turned on the Am241 reference lines to show that the Np and Au peaks are very small in comparison.? One quickly learns to recognize and ignore them when identifying the important peaks that emanate from the target: Ti, Mn, Fe, Ta, Th, U, Y, Zr, Nb, REEs.
After trying many slight thickness variations of Source Filter components, the best result is show in the second picture.
First up is the spectra coming out of the Am exciter source with just a paper alpha blocking filter. That alone made significant improvements at the low end vs no alpha filter. The goal of this project is to apply a filter to the source that will effectively remove most of the low energy component that is caused by Np- daughter and self-XRF of elements in the button, such as Au, Ag, Fe.
Error! Filename not specified.
Now a filter applied to the source and another Gamma Spectrum ran.
Error! Filename not specified.
Thanks to member Dudley Emer for the design of the filter elements and thicknesses, based on selective filtering using the K-edge X-Ray absorption effect.
Hi guys I am interested in drinking water quality testing and most drinking water test kits are not accurate. They give positive readings on concentrated samples like sewage and not for trace elements in drinking water. So I wanted to try out this interesting Chinese? gadget. Search you tube for..?Water Electrolyzer (Quality Tester). The Most Dangerous Appliance Ever? Negative comments being dangerous? and a scam. I checked it out There are 2 pairs of electrodes A shiny aluminium and a dull? iron pair. Repeated usage caused the? iron to rust. Aluminium was confirmed? by exclusion being shiny,light,cheap and nondescript. My drinking water? sample is RO? waste water . This discharged RO waste water is about 4 times more concentrated than my tap water depending on machine cycling. Concentrated means more residue better than plain tap water for analysis. My 14 in 1test kit was basically negative? for heavy metals. I tested this RO concentrated with this Chinese toy. It produced a brownish residue as expected. Collected it and allowed it dry on cap and a tissue. This cap/tissue was analyzed with Xrf with Am241/Si pin detector. True enough like the you tubers described there is Fe from galvanic reactions. There appears to be Pb peak as well I need to repeat this test with a thicker sample? to confirm . Taray
After running the 19.2us peaking time and being satisfied with the tweaking and calibration, here are the results from a and overnight U L X-Ray test and for comparison an old similar test on the same very weakly radioactive sample using 4.8us PT (both in Gamma Spectrum Analyzer mode- not excited XRF)
The differences are subtle but real, with the clarity of large peaks and better separation on smaller peaks going to the slower peaking time.
However in gross analysis, both are very accurate and would probably be equally useful for element identification purposes. Differences between the scans doesn't translate to a pretty picture, so only .mca's included here.
Thanks for that report Charles. Of the two, can you say what is the lowest peak that can be resolved and is there a difference between them?? My just finished overnight run using the Si-PIN on a weakly radioactive sample for Gamma Spec (not excited XRF) is resolving individual peaks down to less than 1.5 keV. In the Peaking Time topic thread I'll post that test @19.2us PT along with a nearly similar test done last February at 4.8us. The main difference between those seems to be both in the clarity and narrowness of the big peaks, and better performance at the lowest end going to the 19.2.
Today I'll try even longer peaking times, up to 32us just for the historical record.?
I think you've been using 32us and I can't fault your scans, that's for sure.
----- Original Message ----- From: Charles David Young <charlesdavidyoung@...> To: XRF <[email protected]> Sent: Fri, 30 Oct 2020 08:26:25 -0400 (EDT) Subject: Re: FW: [XRF] 59.5keV spectrum cleanup
I did 2 runs on a brannerite specimen.? One like normal (red) and the other with a paper adhesive label covering the buttons.? The proportions of the peaks pretty much look the same to me.
Charles
On Wed, Oct 28, 2020 at 11:30 AM Dude <dfemer@...> wrote:
Charles,
My mistake, I now see the problem you¡¯re using a log energy axis. That should always be linear, counts can be log, lin or sqr as appropriate.
Looking at the png you sent there is something seriously wrong on the low energy below 4 keV. Send the mca file for a look as it may just be a Theremino problem. For these low energies you¡¯ll want to keep the Np in there, but to pull these elements out you really need a high flux rate which the Am source isn¡¯t doing. Even with a tube the efficiencies are very poor and the counts are low making it hard to quantify. However, the Al Si, P, S, Ca and K ?are absolutely essential to determining the basic mineralogy types and every effort should be made to verify their presence.
To get the count times up readjust the gain to look only at the low energy range say from 10 on down and see ff that helps pull them out. Using a tight focused beam and close up to the target will also help concentrate the flux.
Dud
?
From:[email protected] [mailto:[email protected]] On Behalf Of Charles David Young Sent: Wednesday, October 28, 2020 8:12 AM To: XRF Subject: Re: FW: [XRF] 59.5keV spectrum cleanup
?
Geo,
?
I agree and I did not mean to dis this exercise, even if it turns out to be primarily academic.
?
When I get a chance I'll try the paper filter with a mineral like Brannerite (UTi2O6) to see how it affects the Ti peak at 4.5keV.? That is typically the lowest element that is essential to my application.? Other peaks like P, K, Ca would be nice but I have learned to live without them.? If we could somehow dig those out by an adjustment it would be great.
"The filter comes at a cost.? Am I reading it correctly that it reduced the input count to %25 of the non-filtered?? Do we need to wait 4x longer for equal counts when this is used as an exciter? "
?
All that is to be determined Charles. It well may be much worse than that, if the low energies in the beam are what's helping to dig out the low energy XRF signals we are looking for.
?
I agree about our perspective points of view too.?
?
You system is as ideal as can be for your main task, and your display program is an advancement in the area of display and identification, especially for the audience of that group. Now the photography meets the same standard too. No one has added all those dimensions in one place to the amateur mineral group before.? All for science' sake, and I applaud that.
?
For you and others I would recommend trying a paper filter over the exciter source, just to see.
?
The rest is for the X-Ray Physics and X-Ray Optics crowd. We now have an inexpensive but powerful tool in our toolbox that wasn't there 2 days ago.
The filter comes at a cost.? Am I reading it correctly that it reduced the input count to %25 of the non-filtered?? Do we need to wait 4x longer for equal counts when this is used as an exciter?? Was all that low energy activity that is filtered out detrimental or beneficial when the button is used to stimulate XRF in the target?
?
I come at this from a different perspective.? I use the Si-PIN with an Am241 exciter to identify minerals.? In my experience the XRF coming from the target is much stronger than the noise introduced by the Am241, which is mounted on a shield and facing away from the detector.? Attached is a scan of xenotime, which shows a large Y component as well as some U and Pb.? I turned on the Am241 reference lines to show that the Np and Au peaks are very small in comparison.? One quickly learns to recognize and ignore them when identifying the important peaks that emanate from the target: Ti, Mn, Fe, Ta, Th, U, Y, Zr, Nb, REEs.
After trying many slight thickness variations of Source Filter components, the best result is show in the second picture.
First up is the spectra coming out of the Am exciter source with just a paper alpha blocking filter. That alone made significant improvements at the low end vs no alpha filter. The goal of this project is to apply a filter to the source that will effectively remove most of the low energy component that is caused by Np- daughter and self-XRF of elements in the button, such as Au, Ag, Fe.
Error! Filename not specified.
Now a filter applied to the source and another Gamma Spectrum ran.
Error! Filename not specified.
Thanks to member Dudley Emer for the design of the filter elements and thicknesses, based on selective filtering using the K-edge X-Ray absorption effect.
I did 2 runs on a brannerite specimen.? One like normal (red) and the other with a paper adhesive label covering the buttons.? The proportions of the peaks pretty much look the same to me.
Looking
at the png you sent there is something seriously wrong on the low energy below
4 keV. Send the mca file for a look as it may just be a Theremino problem. For
these low energies you¡¯ll want to keep the Np in there, but to pull these
elements out you really need a high flux rate which the Am source isn¡¯t doing.
Even with a tube the efficiencies are very poor and the counts are low making
it hard to quantify. However, the Al Si, P, S, Ca and K ?are absolutely
essential to determining the basic mineralogy types and every effort should be
made to verify their presence.
To
get the count times up readjust the gain to look only at the low energy range
say from 10 on down and see ff that helps pull them out. Using a tight focused
beam and close up to the target will also help concentrate the flux.
Dud
?
From:[email protected]
[mailto:[email protected]] On Behalf Of Charles David Young Sent: Wednesday, October 28, 2020 8:12 AM To: XRF Subject: Re: FW: [XRF] 59.5keV spectrum cleanup
?
Geo,
?
I agree and I did not mean to dis this exercise, even if it
turns out to be primarily academic.
?
When I get a chance I'll try the paper filter with a mineral
like Brannerite (UTi2O6) to see how it affects the Ti peak at 4.5keV.?
That is typically the lowest element that is essential to my application.?
Other peaks like P, K, Ca would be nice but I have learned to live without
them.? If we could somehow dig those out by an adjustment it would be
great.
"The filter comes at a cost.? Am I reading it
correctly that it reduced the input count to %25 of the non-filtered?? Do
we need to wait 4x longer for equal counts when this is used as an exciter?
"
?
All that is to be determined Charles. It well may be much
worse than that, if the low energies in the beam are what's helping to dig out
the low energy XRF signals we are looking for.
?
I agree about our perspective points of view too.?
?
You system is as ideal as can be for your main task, and
your display program is an advancement in the area of display and
identification, especially for the audience of that group. Now the photography
meets the same standard too. No one has added all those dimensions in one place
to the amateur mineral group before.? All for science' sake, and I applaud
that.
?
For you and others I would recommend trying a paper filter
over the exciter source, just to see.
?
The rest is for the X-Ray Physics and X-Ray Optics crowd. We
now have an inexpensive but powerful tool in our toolbox that wasn't there 2
days ago.
?
Geo
?
?
?
?
?
----- Original Message -----
From: Charles David Young <charlesdavidyoung@...>
To: XRF <[email protected]>
Sent: Wed, 28 Oct 2020 08:33:01 -0400 (EDT)
Subject: Re: FW: [XRF] 59.5keV spectrum cleanup
?
The filter comes at a cost.? Am I reading it correctly
that it reduced the input count to %25 of the non-filtered?? Do we need to
wait 4x longer for equal counts when this is used as an exciter?? Was all
that low energy activity that is filtered out detrimental or beneficial when
the button is used to stimulate XRF in the target?
?
I come at this from a different perspective.? I use the
Si-PIN with an Am241 exciter to identify minerals.? In my experience the
XRF coming from the target is much stronger than the noise introduced by the
Am241, which is mounted on a shield and facing away from the detector.?
Attached is a scan of xenotime, which shows a large Y component as well as some
U and Pb.? I turned on the Am241 reference lines to show that the Np and
Au peaks are very small in comparison.? One quickly learns to recognize
and ignore them when identifying the important peaks that emanate from the
target: Ti, Mn, Fe, Ta, Th, U, Y, Zr, Nb, REEs.
After trying many slight thickness variations of Source
Filter components, the best result is show in the second picture.
First up is the spectra coming out of the Am exciter source with just a paper
alpha blocking filter. That alone made significant improvements at the low end
vs no alpha filter. The goal of this project is to apply a filter to the source
that will effectively remove most of the low energy component that is caused by
Np- daughter and self-XRF of elements in the button, such as Au, Ag, Fe.
Error! Filename not specified.
Now a filter applied to the source and another Gamma Spectrum ran.
Error! Filename not specified.
Thanks to member Dudley Emer for the design of the filter elements and thicknesses,
based on selective filtering using the K-edge X-Ray absorption effect.
----- Original Message ----- From: Dude <dfemer@...> To: [email protected] Sent: Wed, 28 Oct 2020 15:06:47 -0700 (PDT) Subject: Re: [XRF] How about Sodium?
Randall, Wow that¡¯s going to be tough. #1 it has a Ka of only 1.04 keV with a 1 4% yield and # 2 its behind glass sucking up that 1.04. I can't say I've ever seen anything below Al and Al is tough in low concentrations. Down in that region you want a He or vacuum atmosphere and a detector set up for the low energies. It would be nice to see as Na Mg, K, Ca and Al will determine the basic mineralogy composition you're looking at. It is, however, fun to play with in water. Dud -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Randall Buck Sent: Wednesday, October 28, 2020 2:27 PM To: XRF Subject: [XRF] How about Sodium?
I asked before with no response but since you are now down at Ca, it seems appropriate to check again.
Does anyone want a small sample of sodium metal, sealed under argon in glass.
Sounds fancy but it is (they are) just low pressure sodium vapor lamps pulled from working fixtures. When cooled, the sodium vapor condenses to a small lump at the tip of the bulb (they normally run upside down).
(I have the sockets and the 120VAC ballasts as well)
Randall
(X-Ray tube) edge-absorption type Source Filters De-Mystified
essentially saying the same things, the first probably written by a tech the second by a sales person.
From the first link this is what I needed to know, condensed down:
To see an element, you must send in at least 2 keV more of energy to see that element.
Source Filter: Allows you to focus on key elemental ranges to identify elements at detection limits
The green filter is composed of 150 ¦Ìm (6mil) Cu, 25 ¦Ìm (1mil) Ti, and 300 ¦Ìm (12mil) Al. The green filter sees the optimization in a higher energy range, from 13 - 17 keV (Th, Rb, U, Sr, Y, Zr, Nb, Mo). Use 40kVp @30uA
?
The red filter uses 25 ¦Ìm(1mil) Cu, 25 ¦Ìm (1mil) Ti, and 300 ¦Ìm (12mil) Al -with the red filter we end up with a zone of about 9 - 12 keV were there is an ideal signal to background ratio for elements (Pb, Hg As, Br, Au). Use 40kVp @30uA
The black filter (250 ¦Ìm Cu/25 ¦Ìm Ti/300 ¦Ìm Al). You can see much higher peaks for the heaviest elements (Ba, La, ?Ce).?Use 40kVp @30uA or 45kVp @30ua for K¡¯s from La+Ce
?
The above are the K-Edge type filters, utilizing the abrupt change in X-Ray absorption at the K (or L) edge of an element. Each element is different. These are effective and don/t require much in the area of exciter power. FYI what I'm doing with Cd and Al etc. metals is different and requires more power (or longer count times). The Cd for example is more of a secondary-target system with a built in attenuator. I like to think of it simply as a wavelength shifter.
Might as well add the spectrum from the earlier test showing what the modified beam looks like after passing through the Cd filter- exciter was? 1 Am button
Also just now Mo stamp (pure metal) exciter is 30kVp @ 40uA
In earlier experiments (see Cd FAIL!) we gained information and data about how a cadmium (Cd) filter inserted into the exciter beam altered the output of that beam.
That allowed this experiment to use the altered output spectra for a specific purpose.
A similar experiment has been on the back burner for a long time, specifically pointing the source, not at the intended target but an intermediate target, then using the rays excited from that target to excite the target to be analyzed. Up to 2 intermediate targets or crystals have been used in published experiments. Getting all that set up in my counting room would be impossible, due to the space required and the precision geometries needed. Not to mention my setup is not conducive for reflection geometries.
Instead we investigated a transmission type filter (source filter) and learned form those experiments that a cadmium filter would seemingly pass through the Cd K lines at ~23 and ~26 pretty well, and block most everything else. The intention was to see if those monochromatic X-Rays would excited the intended target's K line XRF.
It worked so well, I had to run the same test with the Ge removed to make sure I wasn't chasing a ghost. Both .mcas attached.
Randall, Wow that¡¯s going to be tough. #1 it has a Ka of only 1.04 keV with a 1 4% yield and # 2 its behind glass sucking up that 1.04. I can't say I've ever seen anything below Al and Al is tough in low concentrations. Down in that region you want a He or vacuum atmosphere and a detector set up for the low energies. It would be nice to see as Na Mg, K, Ca and Al will determine the basic mineralogy composition you're looking at. It is, however, fun to play with in water. Dud
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Randall Buck Sent: Wednesday, October 28, 2020 2:27 PM To: XRF Subject: [XRF] How about Sodium?
I asked before with no response but since you are now down at Ca, it seems appropriate to check again.
Does anyone want a small sample of sodium metal, sealed under argon in glass.
Sounds fancy but it is (they are) just low pressure sodium vapor lamps pulled from working fixtures. When cooled, the sodium vapor condenses to a small lump at the tip of the bulb (they normally run upside down).
(I have the sockets and the 120VAC ballasts as well)
----- Original Message ----- From: "Randall Buck" <rbuck@...> To: "XRF" <[email protected]> Sent: Wednesday, October 28, 2020 4:27:26 PM Subject: [XRF] How about Sodium?
I asked before with no response but since you are now down at Ca, it seems appropriate to check again.
Does anyone want a small sample of sodium metal, sealed under argon in glass.
Sounds fancy but it is (they are) just low pressure sodium vapor lamps pulled from working fixtures. When cooled, the sodium vapor condenses to a small lump at the tip of the bulb (they normally run upside down).
(I have the sockets and the 120VAC ballasts as well)
