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 If a piece of information is incorrect, a link outdated, or the presentation choppy or unclear, the user can just click "Edit Page" at the bottom and then fix the mistake.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?]
Attached is an example of how radionuclides can be distributed within a mineral specimen, showing the variability of the depth of these included sources. There is an excellent picture of my knee on one of the slides.
Hi Charles, cool observation. If I may guess at it:
We know from experience that an atom will make XRF if excited by energy from alpha, beta (or electron stream) Gamma, X-Rays etc. Probably many other ways too.
So if you rely on internal energy to do this, it will do so in response to the available radiation from the rock. Some have LOTS, some have very little, some almost none.
One advantage to that way is all the atoms, even those deep within a big rock are being excited. If those XRF rays can get out depends only on the energy of the ray and the overburden.
Rays above 50 keV have little problem penetrating silicon-calcium-oxygen atoms.
This goes for adding external energy or gathering internally generated XRF.
So your method might show up something that an external exciter misses.
But a good exciter will work on a rock that has no discernable radioactivity, the thing is how radioactive is the rock and how radioactive is does the external exciter have to be to equal or better it.....
The pro units have a need for speed so they have X-Ray tubes, blasting the sample with as much as the law allows. We don't actually have a need for speed so we can use tiny little exciters, but as far as the elements at the surface and a little further
inside are concerned, it is much more "exciting" than the stuff coming from deep inside and spread over the entire surface of the rock.
In other words it may be small, but it is concentrated where it counts, we substitute long run times to get the results we need.
Say on another note, do you have enough Trinitite to do some Gamma Spec runs on it with your Si-PIN? You could precisely calibrate the detector with Am, the see if the X-Rays coming from Trinitite are from Np or U atoms, or both.
Geo
----- Original Message -----
From: Charles David Young <charlesdavidyoung@...>
To: [email protected], Mike Loughlin <loughlin3@...>
Sent: Fri, 07 Feb 2020 17:12:15 -0500 (EST)
Subject: [XRF] The case of the missing elements
I recently picked up a specimen of melanocerite-Ce at the mineral show and did a scan without Am241 by depending on the internal radiation.? I was not surprised to see Th La Ce and Nd in the blue plot.
Then I wanted to see if I got the same results using Am241 as an additional exciter.? So I carefully moved the specimen just far enough from the detector to allow me to slide in the Am241 jig.? I was careful to keep the same spot on the rock even though
it looked quite uniform.
Curiously I am now getting additional strong Fe and Y peaks in the red plot.? What could account for this?? I am not surprised that the La Ce Nd are lit up as they are.
I have also attached both .mca files in case one wishes to analyze them.? However, I am not really asking for that.? I would just like to understand why the Am241 lights up the Fe and Y so strongly compared to the internal radiation.? It is kind of a pain
to weed through the Am241 background peaks but it appears that I may not get a complete picture with the internal radiation alone.
Thanks for that Steve, I didn't realize about the varying U/Th ratios, that makes sense.
Until Charles started mentioning then showing the self-excited aspect it never occurred to me to XRF radioactive minerals too. Usually all I did was gamma spec on radioactive rocks, and the XRF was for stable elements only. This mix of both is certainly challenging. Have you seen it referred to in the literature? I can't remember anyone ever mentioning it before.
----- Original Message ----- From: WILLIAM S Dubyk <sdubyk@...> To: [email protected] Sent: Fri, 07 Feb 2020 20:57:12 -0500 (EST) Subject: Re: [XRF] The case of the missing elements
Geo, great explanation but it gets even crazier than that. Different mineral districts have different U/Th ratios, and they are different ages. So you have an unknown ratio of these elements and their decay products, and x-ray emissions from these elements and daughter products will vary not only from one district to another, but even one mineral to another. It will be very inconsistent. An external source such as Am241 will be very consistent.
Another variable will be, as you mentioned, refraction within the target mineral, versus reflection from the exciter used. Just my thoughts.
Hi Charles, cool observation. If I may guess at it:
We know from experience that an atom will make XRF if excited by energy from alpha, beta (or electron stream) Gamma, X-Rays etc. Probably many other ways too.
So if you rely on internal energy to do this, it will do so in response to the available radiation from the rock. Some have LOTS, some have very little, some almost none.
One advantage to that way is all the atoms, even those deep within a big rock are being excited. If those XRF rays can get out depends only on the energy of the ray and the overburden.
Rays above 50 keV have little problem penetrating silicon-calcium-oxygen atoms.
This goes for adding external energy or gathering internally generated XRF.
So your method might show up something that an external exciter misses.
But a good exciter will work on a rock that has no discernable radioactivity, the thing is how radioactive is the rock and how radioactive is does the external exciter have to be to equal or better it.....
The pro units have a need for speed so they have X-Ray tubes, blasting the sample with as much as the law allows. We don't actually have a need for speed so we can use tiny little exciters, but as far as the elements at the surface and a little further inside are concerned, it is much more "exciting" than the stuff coming from deep inside and spread over the entire surface of the rock.
In other words it may be small, but it is concentrated where it counts, we substitute long run times to get the results we need.
Say on another note, do you have enough Trinitite to do some Gamma Spec runs on it with your Si-PIN? You could precisely calibrate the detector with Am, the see if the X-Rays coming from Trinitite are from Np or U atoms, or both.
I recently picked up a specimen of melanocerite-Ce at the mineral show and did a scan without Am241 by depending on the internal radiation.? I was not surprised to see Th La Ce and Nd in the blue plot.
Then I wanted to see if I got the same results using Am241 as an additional exciter.? So I carefully moved the specimen just far enough from the detector to allow me to slide in the Am241 jig.? I was careful to keep the same spot on the rock even though it looked quite uniform.
Curiously I am now getting additional strong Fe and Y peaks in the red plot.? What could account for this?? I am not surprised that the La Ce Nd are lit up as they are.
I have also attached both .mca files in case one wishes to analyze them.? However, I am not really asking for that.? I would just like to understand why the Am241 lights up the Fe and Y so strongly compared to the internal radiation.? It is kind of a pain to weed through the Am241 background peaks but it appears that I may not get a complete picture with the internal radiation alone.
Geo, great explanation but it gets even crazier than that. Different mineral districts have different U/Th ratios, and they are different ages. So you have an unknown ratio of these elements and their decay products, and x-ray emissions from these elements
and daughter products will vary not only from one district to another, but even one mineral to another. It will be very inconsistent. An external source such as Am241 will be very consistent.
Another variable will be, as you mentioned, refraction within the target mineral, versus reflection from the exciter used. Just my thoughts.
Hi Charles, cool observation. If I may guess at it:
We know from experience that an atom will make XRF if excited by energy from alpha, beta (or electron stream) Gamma, X-Rays etc. Probably many other ways too.
So if you rely on internal energy to do this, it will do so in response to the available radiation from the rock. Some have LOTS, some have very little, some almost none.
One advantage to that way is all the atoms, even those deep within a big rock are being excited. If those XRF rays can get out depends only on the energy of the ray and the overburden.
Rays above 50 keV have little problem penetrating silicon-calcium-oxygen atoms.
This goes for adding external energy or gathering internally generated XRF.
So your method might show up something that an external exciter misses.
But a good exciter will work on a rock that has no discernable radioactivity, the thing is how radioactive is the rock and how radioactive is does the external exciter have to be to equal or better it.....
The pro units have a need for speed so they have X-Ray tubes, blasting the sample with as much as the law allows. We don't actually have a need for speed so we can use tiny little exciters, but as far as the elements at the surface and a little further
inside are concerned, it is much more "exciting" than the stuff coming from deep inside and spread over the entire surface of the rock.
In other words it may be small, but it is concentrated where it counts, we substitute long run times to get the results we need.
Say on another note, do you have enough Trinitite to do some Gamma Spec runs on it with your Si-PIN? You could precisely calibrate the detector with Am, the see if the X-Rays coming from Trinitite are from Np or U atoms, or both.
Geo
----- Original Message -----
From: Charles David Young <charlesdavidyoung@...>
To: [email protected], Mike Loughlin <loughlin3@...>
Sent: Fri, 07 Feb 2020 17:12:15 -0500 (EST)
Subject: [XRF] The case of the missing elements
I recently picked up a specimen of melanocerite-Ce at the mineral show and did a scan without Am241 by depending on the internal radiation.? I was not surprised to see Th La Ce and Nd in the blue plot.
Then I wanted to see if I got the same results using Am241 as an additional exciter.? So I carefully moved the specimen just far enough from the detector to allow me to slide in the Am241 jig.? I was careful to keep the same spot on the rock even though
it looked quite uniform.
Curiously I am now getting additional strong Fe and Y peaks in the red plot.? What could account for this?? I am not surprised that the La Ce Nd are lit up as they are.
I have also attached both .mca files in case one wishes to analyze them.? However, I am not really asking for that.? I would just like to understand why the Am241 lights up the Fe and Y so strongly compared to the internal radiation.? It is kind of a pain
to weed through the Am241 background peaks but it appears that I may not get a complete picture with the internal radiation alone.
Hi Charles, cool observation. If I may guess at it:
We know from experience that an atom will make XRF if excited by energy from alpha, beta (or electron stream) Gamma, X-Rays etc. Probably many other ways too.
So if you rely on internal energy to do this, it will do so in response to the available radiation from the rock. Some have LOTS, some have very little, some almost none.
One advantage to that way is all the atoms, even those deep within a big rock are being excited. If those XRF rays can get out depends only on the energy of the ray and the overburden.
Rays above 50 keV have little problem penetrating silicon-calcium-oxygen atoms.
This goes for adding external energy or gathering internally generated XRF.
So your method might show up something that an external exciter misses.
But a good exciter will work on a rock that has no discernable radioactivity, the thing is how radioactive is the rock and how radioactive is does the external exciter have to be to equal or better it.....
The pro units have a need for speed so they have X-Ray tubes, blasting the sample with as much as the law allows. We don't actually have a need for speed so we can use tiny little exciters, but as far as the elements at the surface and a little further inside are concerned, it is much more "exciting" than the stuff coming from deep inside and spread over the entire surface of the rock.
In other words it may be small, but it is concentrated where it counts, we substitute long run times to get the results we need.
Say on another note, do you have enough Trinitite to do some Gamma Spec runs on it with your Si-PIN? You could precisely calibrate the detector with Am, the see if the X-Rays coming from Trinitite are from Np or U atoms, or both.
----- Original Message ----- From: Charles David Young <charlesdavidyoung@...> To: [email protected], Mike Loughlin <loughlin3@...> Sent: Fri, 07 Feb 2020 17:12:15 -0500 (EST) Subject: [XRF] The case of the missing elements
I recently picked up a specimen of melanocerite-Ce at the mineral show and did a scan without Am241 by depending on the internal radiation.? I was not surprised to see Th La Ce and Nd in the blue plot.
Then I wanted to see if I got the same results using Am241 as an additional exciter.? So I carefully moved the specimen just far enough from the detector to allow me to slide in the Am241 jig.? I was careful to keep the same spot on the rock even though it looked quite uniform.
Curiously I am now getting additional strong Fe and Y peaks in the red plot.? What could account for this?? I am not surprised that the La Ce Nd are lit up as they are.
I have also attached both .mca files in case one wishes to analyze them.? However, I am not really asking for that.? I would just like to understand why the Am241 lights up the Fe and Y so strongly compared to the internal radiation.? It is kind of a pain to weed through the Am241 background peaks but it appears that I may not get a complete picture with the internal radiation alone.
"although I don¡¯t recall that he quantified percentages of each of the metals in the mix."
Ken I don't have the program to do that. It is very costly. All I can do? is (to try to) identify elements.
The Mystery Wire insulation is very Teflon like, I haven't tried its melting point yet. We use all Teflon wire in the shop, some has a really high melting point. Because if the tiny little silver plated wires inside our hookup wire, we use a heat-stripper. It has adjustable temp and can be read with an IR thermometer.
----- Original Message ----- From: Ken Sejkora <kjsejkora@...> To: [email protected] Sent: Fri, 07 Feb 2020 18:37:56 -0500 (EST) Subject: Re: [XRF] Mystery wire
Hi Dud,
?
Thanks for the very detailed analysis of the mystery wire.? I see in the description that you call it ¡®insulated wire¡¯.? Was the insulation still on the wire when you ran the analysis, or had the insulation been removed?? I don¡¯t know for certain, but suspect the insulation might possibly be Teflon, or something of similar nature.? If the analysis was performed with the insulation still on the wire, could that account for some of the low-energy (LE) response, potentially from the Carbon, Chlorine, and Fluorine, etc. if the insulation was indeed Teflon?
?
I¡¯ll have to pull out Geo¡¯s results and see how they compare, although I don¡¯t recall that he quantified percentages of each of the metals in the mix. Again, many thanks for your analysis of the wire.?
?
Have a great weekend.
?
73s? --? Ken
?
?
From: Dude Sent: Friday, February 7, 2020 04:05 PM To: [email protected] Subject: [XRF] Mystery wire
?
Ken,
Attached are the results of your Mystery Wire.
The data were taken with an Olympus DP4050 pXRF. As I don¡¯t have an ALLOY calibration for this gun I used the Mining Mode to get the percentage of elements present
The set up used a 50kV 11 uA x-ray beam with a live time of 30 secs obtaining account rate of 9505 cps from the SDD detector.
?
Mn was identified but it has an interference from Cr and Fe, probably there but not confirmed
From:[email protected] [mailto:[email protected]]
On Behalf Of Charles David Young Sent: Friday, February 7, 2020 2:12 PM To:[email protected]; Mike Loughlin Subject: [XRF] The case of the missing elements
?
I recently picked up a specimen of melanocerite-Ce at the
mineral show and did a scan without Am241 by depending on the internal
radiation.? I was not surprised to see Th La Ce and Nd in the blue plot.
?
Then I wanted to see if I got the same results using Am241
as an additional exciter.? So I carefully moved the specimen just far
enough from the detector to allow me to slide in the Am241 jig.? I was
careful to keep the same spot on the rock even though it looked quite uniform.
?
Curiously I am now getting additional strong Fe and Y peaks
in the red plot.? What could account for this?? I am not surprised
that the La Ce Nd are lit up as they are.
?
I have also attached both .mca files in case one wishes to
analyze them.? However, I am not really asking for that.? I would
just like to understand why the Am241 lights up the Fe and Y so strongly
compared to the internal radiation.? It is kind of a pain to weed through
the Am241 background peaks but it appears that I may not get a complete picture
with the internal radiation alone.
Thanks for the very detailed analysis of the mystery wire.? I see in the description that you call it ¡®insulated wire¡¯.? Was the insulation still on the wire when you ran the analysis, or had the insulation been removed?? I don¡¯t know for certain, but suspect the insulation might possibly be Teflon, or something of similar nature.? If the analysis was performed with the insulation still on the wire, could that account for some of the low-energy (LE) response, potentially from the Carbon, Chlorine, and Fluorine, etc. if the insulation was indeed Teflon?
?
I¡¯ll have to pull out Geo¡¯s results and see how they compare, although I don¡¯t recall that he quantified percentages of each of the metals in the mix. Again, many thanks for your analysis of the wire.?
From: Dude Sent: Friday, February 7, 2020 04:05 PM To: [email protected] Subject: [XRF] Mystery wire
?
Ken,
Attached are the results of your Mystery Wire.
The data were taken with an Olympus DP4050 pXRF. As I don¡¯t have an ALLOY calibration for this gun I used the Mining Mode to get the percentage of elements present
The set up used a 50kV 11 uA x-ray beam with a live time of 30 secs obtaining account rate of 9505 cps from the SDD detector.
?
Mn was identified but it has an interference from Cr and Fe, probably there but not confirmed
I recently picked up a specimen of melanocerite-Ce at the mineral show and did a scan without Am241 by depending on the internal radiation.? I was not surprised to see Th La Ce and Nd in the blue plot.
Then I wanted to see if I got the same results using Am241 as an additional exciter.? So I carefully moved the specimen just far enough from the detector to allow me to slide in the Am241 jig.? I was careful to keep the same spot on the rock even though it looked quite uniform.
Curiously I am now getting additional strong Fe and Y peaks in the red plot.? What could account for this?? I am not surprised that the La Ce Nd are lit up as they are.
I have also attached both .mca files in case one wishes to analyze them.? However, I am not really asking for that.? I would just like to understand why the Am241 lights up the Fe and Y so strongly compared to the internal radiation.? It is kind of a pain to weed through the Am241 background peaks but it appears that I may not get a complete picture with the internal radiation alone.
----- Original Message ----- From: Dude <dfemer@...> To: [email protected] Sent: Fri, 07 Feb 2020 15:59:56 -0500 (EST) Subject: [XRF] Mystery wire
Ken,
Attached are the results of your Mystery Wire.
The data were taken with an Olympus DP4050 pXRF. As I don¡¯t have an ALLOY calibration for this gun I used the Mining Mode to get the percentage of elements present
The set up used a 50kV 11 uA x-ray beam with a live time of 30 secs obtaining account rate of 9505 cps from the SDD detector.
?
Mn was identified but it has an interference from Cr and Fe, probably there but not confirmed
The data were taken with an Olympus DP4050 pXRF. As I don¡¯t
have an ALLOY calibration for this gun I used the Mining Mode to get the
percentage of elements present
The set up used a 50kV 11 uA x-ray beam with a live time of
30 secs obtaining account rate of 9505 cps from the SDD detector.
?
Mn was identified but it has an interference from Cr and Fe,
probably there but not confirmed
Sounds good.? These two big side holes are from the two inch PMT units.? ?I also have the thick shield tubes from them.? It's heavy like lead but adds you can see looks like copper/bronze, probably a passivation layer??
I'm in San Antonio so LN2 shouldn't be an issue,? but haven't checked prices yet.?
"I think the shield from a liquid scint counter I parted out will work for this with some work. "
No doubt, we did learn the lining (passivation layer) is nearly as important as the safety shielding.
Nothing wrong w LN2 if you lie in/near a city and can get it delivered. I hear Carl W. transports it in the trunk of his car (not recommended).
Great on the Kevex, now look at the THERMO power supplies, some as low as $30, and will handle an SDD. If it's a Si-PIN, then the DP-5 should work with it. My SDD is another brand, and won't work with DP-5 (yet- it should when the DP5 is set up as a stand alone MCA). SDD uses high voltage of opposite polarity from Si-PIN.
DP-5 stacks marked Si-PIN will drive the SI-PIN with its own preamp nothing else needed. For use with other detectors, the PC5 isn't used, just the DP5 which must be configured as a stand alone MCA, but there is no preamp in in the DP5.
Geo
----- Original Message ----- From: Nick Andrews <nickjandrews@...> To: [email protected] Sent: Fri, 07 Feb 2020 10:48:29 -0500 (EST) Subject: Re: [XRF] 2020 Portable X-Ray Tube XRF Outfit.Sensor Port Upgrades
Cool.? ?I think the shield from a liquid scint counter I parted out will work for this with some work. While I can foresee moving to a more modern (no LN2 needed) detector than the HPGe, I did buy the thing so I might as well play with it. If it works.?
I did pick up that Kevex fan cooled detector for $200?and that should be interesting to try. It arrives Monday.?
On the Amptek board stacks.? ?What's the consensus on value??
The inner aluminum layer is held in place inside the lead layer by a threaded pipe. The length of that pipe limits the insertion depth when that hole is used for the sensor port:
New machined threaded coupling pipe allows for greater insertion and can be trimmed another 1/4" if needed. The diameter was also increased to allow other probes to be inserted into this port.
However, the design allows the Exciter Port to be located anywhere on the floor of the chamber:
When the beam leaves the Exciter Module, its is round and 10mm diameter:
?By the time it leaves the floor of the chamber it is slightly larger and at 3" from the Exciter Module brass fitting it is 25mm diameter.
Beam diameter test jig (Shop-Built Industrial Spinthariscope):
Re: 2020 Portable X-Ray Tube XRF Outfit.Sensor Port Upgrades
"I think the shield from a liquid scint counter I parted out will work for this with some work. "
No doubt, we did learn the lining (passivation layer) is nearly as important as the safety shielding.
Nothing wrong w LN2 if you lie in/near a city and can get it delivered. I hear Carl W. transports it in the trunk of his car (not recommended).
Great on the Kevex, now look at the THERMO power supplies, some as low as $30, and will handle an SDD. If it's a Si-PIN, then the DP-5 should work with it. My SDD is another brand, and won't work with DP-5 (yet- it should when the DP5 is set up as a stand alone MCA). SDD uses high voltage of opposite polarity from Si-PIN.
DP-5 stacks marked Si-PIN will drive the SI-PIN with its own preamp nothing else needed. For use with other detectors, the PC5 isn't used, just the DP5 which must be configured as a stand alone MCA, but there is no preamp in in the DP5.
----- Original Message ----- From: Nick Andrews <nickjandrews@...> To: [email protected] Sent: Fri, 07 Feb 2020 10:48:29 -0500 (EST) Subject: Re: [XRF] 2020 Portable X-Ray Tube XRF Outfit.Sensor Port Upgrades
Cool.? ?I think the shield from a liquid scint counter I parted out will work for this with some work. While I can foresee moving to a more modern (no LN2 needed) detector than the HPGe, I did buy the thing so I might as well play with it. If it works.?
I did pick up that Kevex fan cooled detector for $200?and that should be interesting to try. It arrives Monday.?
On the Amptek board stacks.? ?What's the consensus on value??
The inner aluminum layer is held in place inside the lead layer by a threaded pipe. The length of that pipe limits the insertion depth when that hole is used for the sensor port:
New machined threaded coupling pipe allows for greater insertion and can be trimmed another 1/4" if needed. The diameter was also increased to allow other probes to be inserted into this port.
However, the design allows the Exciter Port to be located anywhere on the floor of the chamber:
When the beam leaves the Exciter Module, its is round and 10mm diameter:
?By the time it leaves the floor of the chamber it is slightly larger and at 3" from the Exciter Module brass fitting it is 25mm diameter.
Beam diameter test jig (Shop-Built Industrial Spinthariscope):
Re: 2020 Portable X-Ray Tube XRF Outfit.Sensor Port Upgrades
Cool.? ?I think the shield from a liquid scint counter I parted out will work for this with some work. While I can foresee moving to a more modern (no LN2 needed) detector than the HPGe, I did buy the thing so I might as well play with it. If it works.?
I did pick up that Kevex fan cooled detector for $200?and that should be interesting to try. It arrives Monday.?
On the Amptek board stacks.? ?What's the consensus on value??
The inner aluminum layer is held in place inside the lead layer by a threaded pipe. The length of that pipe limits the insertion depth when that hole is used for the sensor port:
New machined threaded coupling pipe allows for greater insertion and can be trimmed another 1/4" if needed. The diameter was also increased to allow other probes to be inserted into this port.
However, the design allows the Exciter Port to be located anywhere on the floor of the chamber:
When the beam leaves the Exciter Module, its is round and 10mm diameter:
?By the time it leaves the floor of the chamber it is slightly larger and at 3" from the Exciter Module brass fitting it is 25mm diameter.
Beam diameter test jig (Shop-Built Industrial Spinthariscope):
From:[email protected]
[mailto:[email protected]] On Behalf Of GEOelectronics@... Sent: Thursday, February 6, 2020 11:56 AM To:[email protected] Subject: Re: [XRF] 2020 Portable X-Ray Tube XRF Outfit.Sensor Port
Upgrades
?
The inner aluminum layer is
held in place inside the lead layer by a threaded pipe. The length of that pipe
limits the insertion depth when that hole is used for the sensor port:
New machined threaded coupling pipe allows for greater insertion and can be
trimmed another 1/4" if needed. The diameter was also increased to allow
other probes to be inserted into this port.
However, the design allows the Exciter Port to be located anywhere on the floor
of the chamber:
When the beam leaves the Exciter Module, its is round and 10mm diameter:
?By the time it leaves the floor of the chamber it is slightly
larger and at 3" from the Exciter Module brass fitting it is 25mm
diameter.
Beam diameter test jig (Shop-Built Industrial Spinthariscope):
Re: 2020 Portable X-Ray Tube XRF Outfit.Sensor Port Upgrades
The inner aluminum layer is held in place inside the lead layer by a threaded pipe. The length of that pipe limits the insertion depth when that hole is used for the sensor port:
New machined threaded coupling pipe allows for greater insertion and can be trimmed another 1/4" if needed. The diameter was also increased to allow other probes to be inserted into this port.
However, the design allows the Exciter Port to be located anywhere on the floor of the chamber:
When the beam leaves the Exciter Module, its is round and 10mm diameter:
?By the time it leaves the floor of the chamber it is slightly larger and at 2.25" from the Exciter Module brass fitting it is 25mm diameter.
Beam diameter test jig (Shop-Built Industrial Spinthariscope):
Aluminum scrap from the shop, for some unknown past project:
Top view
The thickness is fine, works as expected to eliminate unwanted XRF, but the diameter is way to large. Initial testing shows scattering from exposed edges, so new final version of the lid will have all the internal aluminum XRF passivation layer shielded on the outside by 1/4" of Pb. The aluminum interior is to provide clean spectrum scans, reducing or eliminating Pb XRF from the personnel safety shielding.
Lathe rough cut to dimensions for fit testing:
As expected, the plug section is 1mm oversized, and the retainer lip on top is way to thick. More measurements were taken, then back to the shop for the final machining cuts.
More test fitting, then back to lathe for touch-up and polishing. ?The finished piece:
and the fit test:
Now all that's left to do is craft the final layer of the top from 1/4" Pb and a handle.
Dud,
I'll look at the link tomorrow, thanks. Meantime, per your request,?
my? module gives a 10mm round beam at the surface of the brass port that
is part of the module. 3 inches away the spot it still circular and has spread
to 25mm.
?
?
Geo
?
-----
Original Message -----
From: Dude <dfemer@...>
To: [email protected]
Sent: Wed, 05 Feb 2020 19:19:29 -0500 (EST)
Subject: Re: [XRF] Stainless Steel XRF
?
Geo,
You
use XRF filters to remove tube artifacts, Brem, ?and
fine tune low energy response. The filters are used in conjunction with the
tube voltage and the filter material is tailored for the absorption edge for
the analytes you are interested in. ?Putting a 4.8mm block of Al will
reduce
the 50 kV intensity by a factor 0.6, at 30 kV the beam is attenuated down to
0.2. At 20 kV its gone at 0.012.? The only thing ¾±³Ù¡¯²õ doing is killing
your
beam intensity (count time) and shape resulting in excitation only by the
highest
energies.? For looking at a broad band range of elements don¡¯t use a
filter.
When looking to reduce noise select a filter and beam kV tailored to that
material of interest.? Filters are used to maximize the sensitivity to
different groups of elements.? They are not thick, they are thin, a couple
of um
to mils, and are single or layered composite of Al , Ti, Cu, C, Pd, In,
etc.?
Filters are used to tailor the excitation ?energy range. The filter is
designed
to absorb x-rays with energies immediately above the absorption edge of the
filter
material.? Lower energy x-rays and the much higher energy x-rays will make
it ?through.?
This reduces the Brem just above the absorption edge.? For an Al filter
(not a 4.8
mm! but a mil or so), the absorption edge of Al is 1.56 keV so the Ka of the
lower
Z elements Mg (1.2 keV) and Na (1.0 keV) will be absorbed by filter while the
region just above that will have a very low background allowing better
sensitivity to elements from Si (1.7 keV) to Ca (3.7) due to the lower brem.
Above that the higher energies are unaffected.? The filter is used to help
pull
up the sensitivity in energy ranges defined by the element¡¯s Z.
The
?only thing you are doing with the Al block is
reducing the total excitation flux rate, lowering the low energy flux rate and
killing
the low energy element sensitivity while increasing the count time.
Take
the Al filter out. ?If you¡¯re getting Sum peaks then
attenuate the beam but use the beam current first.
"
Geo,Why is
there ?4.8mm of Al attenuator in the beam path? "
?
Two
reasons, the first is to selectively block the lowest energies from the tube
(to help the detector see less noise at the area of interest below 15keV, then
the top layer is to control beam spreading and provide a clear path (1mm hole)
for the beam I want to strike the target.
?
Some
of the same thought went into the Am_X8 to reduce the 13.9 +17.74 but leave the
59.5 pretty much unaffected flux-wise.
Dud, I'll look at the link tomorrow, thanks. Meantime, per your request,? my? module gives a 10mm round beam at the surface of the brass port that is part of the module.2.25 inches away the spot it still circular and has spread to 25mm.
----- Original Message ----- From: Dude <dfemer@...> To: [email protected] Sent: Wed, 05 Feb 2020 19:19:29 -0500 (EST) Subject: Re: [XRF] Stainless Steel XRF
?
?
Geo,
You use XRF filters to remove tube artifacts, Brem, ?and fine tune low energy response. The filters are used in conjunction with the tube voltage and the filter material is tailored for the absorption edge for the analytes you are interested in. ?Putting a 4.8mm block of Al will reduce the 50 kV intensity by a factor 0.6, at 30 kV the beam is attenuated down to 0.2. At 20 kV its gone at 0.012.? The only thing ¾±³Ù¡¯²õ doing is killing your beam intensity (count time) and shape resulting in excitation only by the highest energies.? For looking at a broad band range of elements don¡¯t use a filter. When looking to reduce noise select a filter and beam kV tailored to that material of interest.? Filters are used to maximize the sensitivity to different groups of elements.? They are not thick, they are thin, a couple of um to mils, and are single or layered composite of Al , Ti, Cu, C, Pd, In, etc.? Filters are used to tailor the excitation ?energy range. The filter is designed to absorb x-rays with energies immediately above the absorption edge of the filter material.? Lower energy x-rays and the much higher energy x-rays will make it ?through.? This reduces the Brem just above the absorption edge.? For an Al filter (not a 4.8 mm! but a mil or so), the absorption edge of Al is 1.56 keV so the Ka of the lower Z elements Mg (1.2 keV) and Na (1.0 keV) will be absorbed by filter while the region just above that will have a very low background allowing better sensitivity to elements from Si (1.7 keV) to Ca (3.7) due to the lower brem. Above that the higher energies are unaffected.? The filter is used to help pull up the sensitivity in energy ranges defined by the element¡¯s Z.
The ?only thing you are doing with the Al block is reducing the total excitation flux rate, lowering the low energy flux rate and killing the low energy element sensitivity while increasing the count time.
Take the Al filter out. ?If you¡¯re getting Sum peaks then attenuate the beam but use the beam current first.
" Geo,Why is there ?4.8mm of Al attenuator in the beam path? "
?
Two reasons, the first is to selectively block the lowest energies from the tube (to help the detector see less noise at the area of interest below 15keV, then the top layer is to control beam spreading and provide a clear path (1mm hole) for the beam I want to strike the target.
?
Some of the same thought went into the Am_X8 to reduce the 13.9 +17.74 but leave the 59.5 pretty much unaffected flux-wise.
You use XRF filters to remove tube artifacts, Brem, ?and
fine tune low energy response. The filters are used in conjunction with the
tube voltage and the filter material is tailored for the absorption edge for
the analytes you are interested in. ?Putting a 4.8mm block of Al will reduce
the 50 kV intensity by a factor 0.6, at 30 kV the beam is attenuated down to
0.2. At 20 kV its gone at 0.012.? The only thing ¾±³Ù¡¯²õ doing is killing your
beam intensity (count time) and shape resulting in excitation only by the highest
energies.? For looking at a broad band range of elements don¡¯t use a filter.
When looking to reduce noise select a filter and beam kV tailored to that
material of interest.? Filters are used to maximize the sensitivity to
different groups of elements.? They are not thick, they are thin, a couple of um
to mils, and are single or layered composite of Al , Ti, Cu, C, Pd, In, etc.?
Filters are used to tailor the excitation ?energy range. The filter is designed
to absorb x-rays with energies immediately above the absorption edge of the filter
material.? Lower energy x-rays and the much higher energy x-rays will make it ?through.?
This reduces the Brem just above the absorption edge.? For an Al filter (not a 4.8
mm! but a mil or so), the absorption edge of Al is 1.56 keV so the Ka of the lower
Z elements Mg (1.2 keV) and Na (1.0 keV) will be absorbed by filter while the
region just above that will have a very low background allowing better
sensitivity to elements from Si (1.7 keV) to Ca (3.7) due to the lower brem.
Above that the higher energies are unaffected.? The filter is used to help pull
up the sensitivity in energy ranges defined by the element¡¯s Z.
The ?only thing you are doing with the Al block is
reducing the total excitation flux rate, lowering the low energy flux rate and killing
the low energy element sensitivity while increasing the count time.
Take the Al filter out. ?If you¡¯re getting Sum peaks then
attenuate the beam but use the beam current first.
"
Geo,Why is
there ?4.8mm of Al attenuator in the beam path? "
?
Two
reasons, the first is to selectively block the lowest energies from the tube
(to help the detector see less noise at the area of interest below 15keV, then
the top layer is to control beam spreading and provide a clear path (1mm hole)
for the beam I want to strike the target.
?
Some
of the same thought went into the Am_X8 to reduce the 13.9 +17.74 but leave the
59.5 pretty much unaffected flux-wise.
?
Geo
?
-----
Original Message -----
From: Dude <dfemer@...>
To: [email protected]
Sent: Wed, 05 Feb 2020 00:25:05 -0500 (EST)
Subject: Re: [XRF] Stainless Steel XRF
?
Geo,
Why is there ?4.8mm of Al attenuator in the beam path?
?What is the
no collimated diameter of the micro-focus beam on the target? Is it well
aligned with the 1mm collimator, if ¾±³Ù¡¯²õ not you¡¯ll have ?a lot of attenuation.?
Collimation usually uses 2 ?separated collimators and sometimes one on the
detector. ?Start simple, no collimator, no attenuators. Look at the beam
diameter at the target plane. Set up the collimation to get the beam diameter
you want at the target plane. ?Then move the Detector close to the target
say
about 1 ¨C 2cm. ?Take a shot using the lowest beam current and look at Dead
Time.
You should be able to count at 40Kcps and have good resolution and count
time.?
Play with the beam current. Play with Detector distance to target.
Your comment ¡°¡allows the sensor to be considerably close to the center of the
chamber. Not that? it maters very much¡± ?What is considerably
closer? It matters very much. The beam will expose a small circle on the target
that will fluoresce over a solid angle. The flux in is proportional to the flux
out. The percentage of that signal your detector will get is directly dependent
on the distance from the target and that solid angle. Close up its 1/r, at a
distance it falls as 1/r2.? Remember the time distance shielding thing
?Do a sensitivity analysis. What gets the best signal? What
changes
things the most? ¨C where do I optimize my effort? Is it Distance, geometric
angle
between beam and detector, collimation, need for attenuator, what size beam
spot do I want on the target, what s that get me in count time etc.
The problem here is not the difference between a SDD and a SI-PIN
¾±³Ù¡¯²õ
the set up geometry and the shield system limiting you to very poor performance.
Yes,
the exciter flux is very low. Only 20 uA and in the beam port right now are 3
ea. 1.6mm Aluminum plates (solid) and then a 4.75mm plate with a 1mm hole in
the center. I'm please with the clean patterns, even tho slow. This is a
Si-PIN, not an SDD.?
?
I
did machine a new part the other day that connects the Al and Pb?
cylinders together, that allows the sensor to be considerably close to the
center of the chamber. Not that? it maters very much, as the beam can be
positioned anywhere on the floor of the chamber.
?
Also
today, a trip to the garage yielded a good thick aluminum part that can be
turned
on the lather to make the lid-liner,
With
luck, the lid will be finished tomorrow and work on the
permanent collimator started.
" Geo,Why is there ?4.8mm of Al attenuator in the beam path? "
Two reasons, the first is to selectively block the lowest energies from the tube (to help the detector see less noise at the area of interest below 15keV, then the top layer is to control beam spreading and provide a clear path (1mm hole) for the beam I want to strike the target.
Some of the same thought went into the Am_X8 to reduce the 13.9 +17.74 but leave the 59.5 pretty much unaffected flux-wise.
----- Original Message ----- From: Dude <dfemer@...> To: [email protected] Sent: Wed, 05 Feb 2020 00:25:05 -0500 (EST) Subject: Re: [XRF] Stainless Steel XRF
Geo,
Why is there ?4.8mm of Al attenuator in the beam path? ?What is the no collimated diameter of the micro-focus beam on the target? Is it well aligned with the 1mm collimator, if ¾±³Ù¡¯²õ not you¡¯ll have ?a lot of attenuation.? Collimation usually uses 2 ?separated collimators and sometimes one on the detector. ?Start simple, no collimator, no attenuators. Look at the beam diameter at the target plane. Set up the collimation to get the beam diameter you want at the target plane. ?Then move the Detector close to the target say about 1 ¨C 2cm. ?Take a shot using the lowest beam current and look at Dead Time. You should be able to count at 40Kcps and have good resolution and count time.? Play with the beam current. Play with Detector distance to target.
Your comment ¡°¡allows the sensor to be considerably close to the center of the chamber. Not that? it maters very much¡± ?What is considerably closer? It matters very much. The beam will expose a small circle on the target that will fluoresce over a solid angle. The flux in is proportional to the flux out. The percentage of that signal your detector will get is directly dependent on the distance from the target and that solid angle. Close up its 1/r, at a distance it falls as 1/r2.? Remember the time distance shielding thing
?Do a sensitivity analysis. What gets the best signal? What changes things the most? ¨C where do I optimize my effort? Is it Distance, geometric angle between beam and detector, collimation, need for attenuator, what size beam spot do I want on the target, what s that get me in count time etc.
The problem here is not the difference between a SDD and a SI-PIN ¾±³Ù¡¯²õ the set up geometry and the shield system limiting you to very poor performance.
Yes, the exciter flux is very low. Only 20 uA and in the beam port right now are 3 ea. 1.6mm Aluminum plates (solid) and then a 4.75mm plate with a 1mm hole in the center. I'm please with the clean patterns, even tho slow. This is a Si-PIN, not an SDD.?
?
I did machine a new part the other day that connects the Al and Pb? cylinders together, that allows the sensor to be considerably close to the center of the chamber. Not that? it maters very much, as the beam can be positioned anywhere on the floor of the chamber.
?
Also today, a trip to the garage yielded a good thick aluminum part that can be turned on the lather to make the lid-liner,
With luck, the lid will be finished tomorrow and work on the permanent collimator started.
Nick Andrews
