Re: Reducing unwanted X-Rays with filters.
If it's the? one with Am_X8, the detector WAS the target. Nothing but air between them. An effort to see it for myself rather than go to the attenuation charts. Info gathered will be useful later.
Geo
----- Original Message ----- From: Dude <dfemer@...> To: [email protected]Sent: Sat, 01 Feb 2020 15:01:22 -0500 (EST) Subject: Re: [XRF] Reducing unwanted X-Rays with filters.
I’ve been out all week with the flu and playing catch up right
now. Charles’s new labeling looks nice. If someone is going to run another Al filter test it would be nice
to use a metal standard as the target so we can see the change in peak amplitude
as a function of ?filter thickness. ?Geo, What was the target material for the filter test? Dud ? ? ? Excellent, George.? I have some 1/64" Al sheeting
that I'll try when I get a chance.? About 5 layers should do it. ? In medical X-Ray imaging, it
was long ago discovered that the lowest energies coming from the X-Ray
generator did nothing at all to improve the image on the film, but rather,
instead of penetrating the target, they were needlessly absorbed by the skin and
upper layers of the body In the early days these unwanted rays became known as
"burning rays" and for good reason. ALL medical X-Ray generators
today have? aluminum filters.
In the science lab, the low powered X-Ray tubes don't have filters, so they
must be added, if needed.
X-Rays from isotopes are also a nuisance especially in the area of XRF
detection. So many of these X-Rays interfere and simply clutter up the scan,
causing all sorts of interpretation problems in the analysis stage.
Am- is particularly bad for this because the daughter Np has X-Rays right in
the middle of our range of interest, the worst being 13.9 and 17.74.
Borrowing the aluminum filter idea from our medical colleagues, an experiment
was conducted to determine if filtering could perhaps clean up our exciters.
Using the Spectrum Techniques RAS absorber set, all of the aluminum filters
were sequentially placed between the business end of an? Am_X8 exciter,
pointing directly at the CdTe detector. CdTe was chosen for these tests because
it gives a truer representation of the 59.5 energy, although the resolution is
much poorer than the Si-PIN.
The Al absorbers were labeled G (0.20" or 129 mg/Mm^2) through P
(0.125" or 849 mg/CM^2), the others in the set being made of plastic and
lead.
A ideal goal was set to chase, 90% reduction of said interfering X-Ray, while
retaining 90% of the 59.5.
Enough data was gathered to make a full blown report, but here are the
highlights in picture form.
First scan, source directly illuminating the detector with NOTHING but air
between them.
Then scan repeated with the 0.20" filter and all the others in sequence,
one at a time.
0.40 was determined to be a very good end point, but the test was continued all
the way to 0.125" to see what happens. The final result, while not being
much use to use directly set off yet another experiment with really thick
aluminum (inches) to examine what was noticed and guessed to be scattering or
channeling within.
Test Zero- NO FILTER NOTE: The outline of this test remains on all others as a
reminder of the original levels.
Test-G-0.020"Aluminum = 129 mg/cm^2
Test-J 0.40 Aluminum= 258 mg/cm^2 looked good, but not quite to the ultimate
goal 90%/10%
Test-M - First to break over 90% reduction @ 17.74, and then some! 0.080"
= 516 mg/cm^2
Have fun,
Geo>K0FF
|
Here's the one from just now, done with the new filter stack:  .mca attached.
|
I think you’re right, Dud.? I questioned the identification of Kr and Ru, but didn’t pursue the possibilities of Kb or sum peaks. Both of your arguments seem like probable explanations given the other constituents in the wire. Krypton would be very unlikely, given its atmospheric content of only 0.000114%. Given that most of the elements in the mystery wire are near-ferrous, the Kb energy from Mo makes more sense for the 19.6 keV peak. ? Thanks for your insights? --? Ken ?
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From: DudeSent: Saturday, February 1, 2020 03:48 PM To: [email protected]Subject: Re: [XRF] Ken's "Mystery Wire" ? Geo, I don’t have the .mca file but looking at the mystery wire .png the Ka1 Ru reported at 19.7 would actually be the Mo Kb1 at 19.6. The no match at 15.55 would appear to be a Ni -Cu sum peak at 15.6. ?It’s not real likely you’re actually seeing intrinsic or atmospheric Kr so my best guess would be a Ni-Cr sum peak at 12.8. If this is from a taught wire PID then we could ?expect it was designed for a very low coefficient of thermal expansion, now how? to test that? Interesting stuff. Dud KK7IF ? ? ?
|
Re: Reducing unwanted X-Rays with filters. TUBE EXCITERS
Beautiful results, 10 second scan. This was a cool project and great experience for the cabinet XRF machine project.?  .mca file attached. Geo>K0FF
|
Reducing unwanted X-Rays with filters. TUBE EXCITERS
A typical X-Ray tube exciter module as made by Kevex, Oxford, Thermo and others is a 10 Watt 50 kV tube that can handle 0.2 mA? (200 microAmps) of current.
This is a good match to "X-Ray Image Intensifiers" which are direct viewers that convert X-Rays first into a weak photo? image on a chemical layer, them amplify that visible light using an image intensifier tube. This intensifier amplifies photo-electrons, smashing them into a phosphor screen where the visible-to-human-eye image appears. It is upside down and backwards, all the ones I have encountered at work are green screen. Reversal can be done optically or electrically
with video cameras. LIXI machines are such devices, marrying the generator and image intensifier together for real time inspection purposes.
XRFing does not require near that much power, so in my XRF chamber, we've tailored the beam shape and intensity with filters to lessen the tramp XRF for the chamber materials itself.
First step measure the bare beam, then determine the tenth-value layer of aluminum for the typical HV and low current needs anticipated for XRF.
Using plates of 1.6mm thick aluminum sheet? from the shop, it was determined by testing with a micro-rem meter that 3 layers reduced the doserate? to less than 10%. at 4" distance from the tube's beryllium window.
Next a collimator was made out of a 4.75mm thick aluminum disc. This we drilled? a #55 hole in the center and stacked it on top of the filters, and except for the beam hole, further reduced the remaining 10% from the filters by another 90%.
What is left is a clean beam, with the tramp XRF from the X-Ray tube housing's bronze bushing filtered out.
Measuring the final setup at the very top of the chamber we see 1.24 R/m without the filter stack and only 0.03 R/m with the filter stack installed (Fluke Rad-Check plus Mdl 06-526).
Sample loaded  Results up next. Geo
|
Geo,
I don’t have the .mca file but looking at the mystery wire .png
the Ka1 Ru reported at 19.7 would actually be the Mo Kb1 at 19.6.
The no match at 15.55 would appear to be a Ni -Cu sum peak at 15.6.
?It’s not real likely you’re actually seeing intrinsic or atmospheric Kr so my
best guess would be a Ni-Cr sum peak at 12.8.
If this is from a taught wire PID then we could ?expect it was
designed for a very low coefficient of thermal expansion, now how? to test
that?
Interesting stuff.
Dud KK7IF
?
?
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From: [email protected]
[mailto:[email protected]] On Behalf Of GEOelectronics@...
Sent: Wednesday, January 29, 2020 10:12 AM
To: [email protected]
Subject: [XRF] Ken's "Mystery Wire"
?
Member Ken S
sent in a wire labeled "Mystery Wire".
It is silver in color, very hard but not springy. Non magnetic. Extremely light
for its volume.
Many more tests to be done, but XRF was easy, and based on the elemental makeup
my best guess as of today is one of the super alloys under ASTM B649-17
ASTM B649 - 17 
Standard Specification for Ni-Fe-Cr-Mo-Cu-N
Low-Carbon Alloys (UNS N08925, UNS N08031, UNS N08034, UNS N08354
Small mass, non magnetic even though Fe is major, low Ni content, low Cu
content. Not a Nicrome, maybe an Alchrome?
Will test further, hardness, electrical resistivity, thermal
conductivity,? radioactivity etc.
Geo
|
Re: Reducing unwanted X-Rays with filters.
I’ve been out all week with the flu and playing catch up right
now.
Charles’s new labeling looks nice.
If someone is going to run another Al filter test it would be nice
to use a metal standard as the target so we can see the change in peak amplitude
as a function of ?filter thickness.
?Geo, What was the target material for the filter test?
Dud
?
?
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From: [email protected]
[mailto:[email protected]] On Behalf Of Charles David Young
Sent: Friday, January 31, 2020 2:42 PM
To: [email protected]
Subject: Re: [XRF] Reducing unwanted X-Rays with filters.
?
Excellent, George.? I have some 1/64" Al sheeting
that I'll try when I get a chance.? About 5 layers should do it.
?
In medical X-Ray imaging, it
was long ago discovered that the lowest energies coming from the X-Ray
generator did nothing at all to improve the image on the film, but rather,
instead of penetrating the target, they were needlessly absorbed by the skin and
upper layers of the body In the early days these unwanted rays became known as
"burning rays" and for good reason. ALL medical X-Ray generators
today have? aluminum filters.
In the science lab, the low powered X-Ray tubes don't have filters, so they
must be added, if needed.
X-Rays from isotopes are also a nuisance especially in the area of XRF
detection. So many of these X-Rays interfere and simply clutter up the scan,
causing all sorts of interpretation problems in the analysis stage.
Am- is particularly bad for this because the daughter Np has X-Rays right in
the middle of our range of interest, the worst being 13.9 and 17.74.
Borrowing the aluminum filter idea from our medical colleagues, an experiment
was conducted to determine if filtering could perhaps clean up our exciters.
Using the Spectrum Techniques RAS absorber set, all of the aluminum filters
were sequentially placed between the business end of an? Am_X8 exciter,
pointing directly at the CdTe detector. CdTe was chosen for these tests because
it gives a truer representation of the 59.5 energy, although the resolution is
much poorer than the Si-PIN.
The Al absorbers were labeled G (0.20" or 129 mg/Mm^2) through P
(0.125" or 849 mg/CM^2), the others in the set being made of plastic and
lead.
A ideal goal was set to chase, 90% reduction of said interfering X-Ray, while
retaining 90% of the 59.5.
Enough data was gathered to make a full blown report, but here are the
highlights in picture form.
First scan, source directly illuminating the detector with NOTHING but air
between them.
Then scan repeated with the 0.20" filter and all the others in sequence,
one at a time.
0.40 was determined to be a very good end point, but the test was continued all
the way to 0.125" to see what happens. The final result, while not being
much use to use directly set off yet another experiment with really thick
aluminum (inches) to examine what was noticed and guessed to be scattering or
channeling within.
Test Zero- NO FILTER NOTE: The outline of this test remains on all others as a
reminder of the original levels.
Test-G-0.020"Aluminum = 129 mg/cm^2
Test-J 0.40 Aluminum= 258 mg/cm^2 looked good, but not quite to the ultimate
goal 90%/10%
Test-M - First to break over 90% reduction @ 17.74, and then some! 0.080"
= 516 mg/cm^2
Have fun,
Geo>K0FF
|
Interesting observation, Geo.? I had noticed the same thing, that the end seems to be more ‘magnetic’ than the sides.? It might be interesting to take a weak magnet and try the same thing with a more strongly magnetic object like a paperclip or small screw.? I’m guessing this phenomenon is NOT unique to the “mystery wire”. ? I know if you “pick up” a pile of pins or paperclips with a magnet, they stick together end-to-end, versus side-to-side.? Same goes for picking up a screw with a slightly magnetized screwdriver… the attraction seems stronger at the ends of the screw, rather than along its length.? I wonder if the intensity of the magnetic flux is stronger on the small cross section of the end of a relatively long (much larger in length compared to diameter), than if the field is dispersed along the length of the object when picking it up along its side. ? I’m guessing your observation has more to do with the physics behind magnetic fields, than it has to do with the homogeneity of the elemental composition of the wire itself.? I guess that there might be a possibility the “mystery wire” has an iron/steel core, and is otherwise plated/clad/coated with the other metallic components.? I guess one could stick the wire into the chuck of a drill and grind off the outer layer, and reanalyze it with the XRF.? If there is a coating on the wire, the new XRF should be different than the first.? However, if the wire is homogeneous in composition throughout, then the two spectra should be relatively the same. ? That was actually the impetus behind my first question related to ‘resolution’ (for lack of better terms) of XRF in delineating a homogeneous-composition alloy from a plated/coated object containing the same elemental mix.? The example of brass alloy versus the copper-clad penny. ? Thanks for all of your efforts in this inquiry, Geo. ? I hope everyone has a fantastic weekend --? Ken ?
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Show quoted text
From: GEOelectronics@...Sent: Friday, January 31, 2020 04:44 PM To: [email protected]Subject: Re: [XRF] Ken's "Mystery Wire" ? On Thu, Jan 30, 2020 at 04:05 PM, Ken Sejkora wrote: If you still have your supermagnet, handy check the ends of the wire vs the sides of the wire with it. There seems to be a dramatic difference. See the video clip:
does that seem normal?
Geo ?
|
On Thu, Jan 30, 2020 at 01:38 PM, Ken Sejkora wrote:
that works out to a resistivity of 0.00893 Ohms/cm.?
Looks good Ken.?
I get? 0.00850 but the millivoltmeter hasn't been turned on for a while. Will check again tomorrow after leaving it on overnight. One desk in the shop is setup just for resistor testing, we use hand selected resistors in projects and want to be able to test them under actual HV conditions same goes for capacitors.
Geo
Geo
|
Re: Reducing unwanted X-Rays with filters. ISOTOPE EXCITERS
Thanks Charles.
Even a little helps. Most of my interference is scattered off the target, so the less we present to it the better. No way nor do we need to worry about the 59.5, it's above the range we mostly use anyway. Makes a good calibration point tho. Wish I had thot of that when making 3 months worth of scans at 8k channels back in 2014. Oh well live and learn.
Geo
|
Re: Reducing unwanted X-Rays with filters. ISOTOPE EXCITERS
Excellent, George.? I have some 1/64" Al sheeting that I'll try when I get a chance.? About 5 layers should do it.
Charles
In medical X-Ray imaging, it was long ago discovered that the lowest energies coming from the X-Ray generator did nothing at all to improve the image on the film, but rather, instead of penetrating the target, they were needlessly absorbed by the skin and upper layers of the body In the early days these unwanted rays became known as "burning rays" and for good reason. ALL medical X-Ray generators today have? aluminum filters.In the science lab, the low powered X-Ray tubes don't have filters, so they must be added, if needed.X-Rays from isotopes are also a nuisance especially in the area of XRF detection. So many of these X-Rays interfere and simply clutter up the scan, causing all sorts of interpretation problems in the analysis stage.Am- is particularly bad for this because the daughter Np has X-Rays right in the middle of our range of interest, the worst being 13.9 and 17.74.
Borrowing the aluminum filter idea from our medical colleagues, an experiment was conducted to determine if filtering could perhaps clean up our exciters.
Using the Spectrum Techniques RAS absorber set, all of the aluminum filters were sequentially placed between the business end of an? Am_X8 exciter, pointing directly at the CdTe detector. CdTe was chosen for these tests because it gives a truer representation of the 59.5 energy, although the resolution is much poorer than the Si-PIN.
The Al absorbers were labeled G (0.20" or 129 mg/Mm^2) through P (0.125" or 849 mg/CM^2), the others in the set being made of plastic and lead.
A ideal goal was set to chase, 90% reduction of said interfering X-Ray, while retaining 90% of the 59.5.
Enough data was gathered to make a full blown report, but here are the highlights in picture form.
First scan, source directly illuminating the detector with NOTHING but air between them.
Then scan repeated with the 0.20" filter and all the others in sequence, one at a time.
0.40 was determined to be a very good end point, but the test was continued all the way to 0.125" to see what happens. The final result, while not being much use to use directly set off yet another experiment with really thick aluminum (inches) to examine what was noticed and guessed to be scattering or channeling within.
Test Zero- NO FILTER NOTE: The outline of this test remains on all others as a reminder of the original levels.
Test-G-0.020"Aluminum = 129 mg/cm^2
Test-J 0.40 Aluminum= 258 mg/cm^2 looked good, but not quite to the ultimate goal 90%/10%
Test-M - First to break over 90% reduction @ 17.74, and then some! 0.080" = 516 mg/cm^2
Have fun,
Geo>K0FF
|
On Thu, Jan 30, 2020 at 04:05 PM, Ken Sejkora wrote:
it might make sense to “tune” the wire composition to be relatively ‘neutral’, that is, neither ferromagnetic (e.g., steel wire), diamagnetic (e.g., copper wire), and minimally paramagnetic.
Interesting. Now that you reminded, I think there are still some neutral coil adjusting tools down in the workshop, left over from the radio says. I'll dig one of those out and test it on XRF. for fun. If you still have your supermagnet, handy check the ends of the wire vs the sides of the wire with it. There seems to be a dramatic difference. See the video clip: does that seem normal? Geo
|
Reducing unwanted X-Rays with filters. ISOTOPE EXCITERS
In medical X-Ray imaging, it was long ago discovered that the lowest energies coming from the X-Ray generator did nothing at all to improve the image on the film, but rather, instead of penetrating the target, they were needlessly absorbed by the skin and upper layers of the body In the early days these unwanted rays became known as "burning rays" and for good reason. ALL medical X-Ray generators today have? aluminum filters.In the science lab, the low powered X-Ray tubes don't have filters, so they must be added, if needed.X-Rays from isotopes are also a nuisance especially in the area of XRF detection. So many of these X-Rays interfere and simply clutter up the scan, causing all sorts of interpretation problems in the analysis stage.Am- is particularly bad for this because the daughter Np has X-Rays right in the middle of our range of interest, the worst being 13.9 and 17.74.
Borrowing the aluminum filter idea from our medical colleagues, an experiment was conducted to determine if filtering could perhaps clean up our exciters.
Using the Spectrum Techniques RAS absorber set, all of the aluminum filters were sequentially placed between the business end of an? Am_X8 exciter, pointing directly at the CdTe detector. CdTe was chosen for these tests because it gives a truer representation of the 59.5 energy, although the resolution is much poorer than the Si-PIN.
The Al absorbers were labeled G (0.20" or 129 mg/Mm^2) through P (0.125" or 849 mg/CM^2), the others in the set being made of plastic and lead.
A ideal goal was set to chase, 90% reduction of said interfering X-Ray, while retaining 90% of the 59.5.
Enough data was gathered to make a full blown report, but here are the highlights in picture form.
First scan, source directly illuminating the detector with NOTHING but air between them.
Then scan repeated with the 0.20" filter and all the others in sequence, one at a time.
0.40 was determined to be a very good end point, but the test was continued all the way to 0.125" to see what happens. The final result, while not being much use to use directly set off yet another experiment with really thick aluminum (inches) to examine what was noticed and guessed to be scattering or channeling within.
Test Zero- NO FILTER NOTE: The outline of this test remains on all others as a reminder of the original levels.
Test-G-0.020"Aluminum = 129 mg/cm^2
Test-J 0.40 Aluminum= 258 mg/cm^2 looked good, but not quite to the ultimate goal 90%/10%
Test-M - First to break over 90% reduction @ 17.74, and then some! 0.080" = 516 mg/cm^2
Have fun,
Geo>K0FF
|
Nice work Charles. Ask if you have any questions, but looks like you already have it figured out.
Geo
----- Original Message ----- From: Charles David Young <charlesdavidyoung@...> To: [email protected], Mike Loughlin <loughlin3@...> Sent: Fri, 31 Jan 2020 11:44:35 -0500 (EST) Subject: [XRF] Ta Y Zr La Ce XRF
I am getting ready to start a series of tests so I wanted to make sure my detector is calibrated correctly using a series of elements.? The results show the calibration to be pretty darn close.
In preparation for these tests I have also upgraded my peak labeling to 3 types: - id - large black font for significant peaks associated with the target
- regular - small black font for peaks that were at least examined
- reference - small red for peaks that are part of the environment: Am241 and Pb
I feel like this labeling system will be useful in clarifying complicated scans.
Charles
|
I am getting ready to start a series of tests so I wanted to make sure my detector is calibrated correctly using a series of elements.? The results show the calibration to be pretty darn close.
In preparation for these tests I have also upgraded my peak labeling to 3 types: - id - large black font for significant peaks associated with the target
- regular - small black font for peaks that were at least examined
- reference - small red for peaks that are part of the environment: Am241 and Pb
I feel like this labeling system will be useful in clarifying complicated scans.
Charles
|
All good tests and yes they add to the knowledge base. Use what you have, make the most of it.
Your last clue was the give away, it's a "taught-wire PID". We won't talk about its tech but we can sure analyze this wire...
Geo
----- Original Message ----- From: Ken Sejkora <kjsejkora@...> To: [email protected]Sent: Thu, 30 Jan 2020 17:05:35 -0500 (EST) Subject: Re: [XRF] Ken's "Mystery Wire"
Greetings to the group, ? Some more interesting properties of the “mystery wire”.? Although I don’t have a way to quantify the results, I can at least qualify the results. ? Regarding the magnetic properties of the wire, it appears to be somewhat “neutral”.? I tried to qualify this in two manners.? I hooked up a small solenoid coil to an inductance meter and determined the inductance of the “bare” core,? that is, nothing within the cavity of the core.? The result was 0.42 mH.? As expected, if I introduced a steel screwdriver into the cavity (ferromagnetic composition, that is, can be formed into a ‘permanent’ magnet), the inductance increased (1.53 mH).? If I introduced a few strands of 16-gauge copper wire (diamagnetic composition, that is, repelled by a magnetic field) into the core, the inductance decreased (0.38 mH). ?A roll of aluminum (paramagnetic composition, that is attracted to a magnetic field) also decreased the inductance (0.39 mH).? When I introduced several strands of the mystery wire into the cavity, the inductance didn’t change at all, suggesting that it may be only paramagnetic (attracted to a magnetic field, although in this case only slightly to a strong neodymium magnet). ? Along a similar vein, I pulled out a cheap metal detector and checked its response to various metals.? When the discriminator was properly tuned and producing a steady tone, a pair of pliers or screwdriver (both steel/iron) produced a softer or absent tone, whereas a spool of copper produced a stronger/louder tone. A spool if the “mystery wire” resulted in no change in the tone when the metal detector passed over it. ? Although metal, the “mystery wire” appears to be almost ‘neutral’ in its response to a magnetic fields.? Granted, a small piece (<1 cm) of the wire will “stick” very loosely to a strong neodymium magnet, it does not appear to produce any detectable response to my two electromagnetic tests. I will admit neither test is by no means quantitative, but I do find the qualitative results intriguing. ? When Geo suggested the wire might be some type of “supermetal”, it made me start thinking.? I began to wonder if the composition of the wire was deliberately “tuned” to have a neutral response.? A bit of background into the wire.? I used to work at a facility that had some E-field sensors around it to detect potential intruders.? The “mystery wire” used to be stretched along the perimeter of the facility to detect any objects entering within the vicinity of the wires.? I have no idea if the process worked on detecting changes in inductance, capacitance, or both, but if one were attempting to minimize the inductive response, it might make sense to “tune” the wire composition to be relatively ‘neutral’, that is, neither ferromagnetic (e.g., steel wire), diamagnetic (e.g., copper wire), and minimally paramagnetic.? On top of that, the mixture is strong, stiff, hard, resilient, and has a high tensile strength.? All of these properties would lend well to creating an E-field sensor. ? All speculation on my part.? Thanks for your analyses, George.? Like you said, aren’t supermetals a hoot?? ? Ken
|
Greetings to the group, ? Some more interesting properties of the “mystery wire”.? Although I don’t have a way to quantify the results, I can at least qualify the results. ? Regarding the magnetic properties of the wire, it appears to be somewhat “neutral”.? I tried to qualify this in two manners.? I hooked up a small solenoid coil to an inductance meter and determined the inductance of the “bare” core,? that is, nothing within the cavity of the core.? The result was 0.42 mH.? As expected, if I introduced a steel screwdriver into the cavity (ferromagnetic composition, that is, can be formed into a ‘permanent’ magnet), the inductance increased (1.53 mH).? If I introduced a few strands of 16-gauge copper wire (diamagnetic composition, that is, repelled by a magnetic field) into the core, the inductance decreased (0.38 mH). ?A roll of aluminum (paramagnetic composition, that is attracted to a magnetic field) also decreased the inductance (0.39 mH).? When I introduced several strands of the mystery wire into the cavity, the inductance didn’t change at all, suggesting that it may be only paramagnetic (attracted to a magnetic field, although in this case only slightly to a strong neodymium magnet). ? Along a similar vein, I pulled out a cheap metal detector and checked its response to various metals.? When the discriminator was properly tuned and producing a steady tone, a pair of pliers or screwdriver (both steel/iron) produced a softer or absent tone, whereas a spool of copper produced a stronger/louder tone. A spool if the “mystery wire” resulted in no change in the tone when the metal detector passed over it. ? Although metal, the “mystery wire” appears to be almost ‘neutral’ in its response to a magnetic fields.? Granted, a small piece (<1 cm) of the wire will “stick” very loosely to a strong neodymium magnet, it does not appear to produce any detectable response to my two electromagnetic tests. I will admit neither test is by no means quantitative, but I do find the qualitative results intriguing. ? When Geo suggested the wire might be some type of “supermetal”, it made me start thinking.? I began to wonder if the composition of the wire was deliberately “tuned” to have a neutral response.? A bit of background into the wire.? I used to work at a facility that had some E-field sensors around it to detect potential intruders.? The “mystery wire” used to be stretched along the perimeter of the facility to detect any objects entering within the vicinity of the wires.? I have no idea if the process worked on detecting changes in inductance, capacitance, or both, but if one were attempting to minimize the inductive response, it might make sense to “tune” the wire composition to be relatively ‘neutral’, that is, neither ferromagnetic (e.g., steel wire), diamagnetic (e.g., copper wire), and minimally paramagnetic.? On top of that, the mixture is strong, stiff, hard, resilient, and has a high tensile strength.? All of these properties would lend well to creating an E-field sensor. ? All speculation on my part.? Thanks for your analyses, George.? Like you said, aren’t supermetals a hoot?? ? Ken
|
Hi Geo, ? I moved in June 2019, so there are still boxes of junk (er, I mean “components”) waiting to be unpacked.? I couldn’t find my 1% 100-Ohm power resistor or original test jig, but was able to dig up a 3% 110-Ohm 25-watt resistor and some jumper wires.? I found the longest piece of the mystery wire I could easily lay out on the floor to measure, and it came out to 354 inches, or just shy of 900 cm.? Hooked up in series with the 110-Ohm resistor to a 12-volt regulated power supply, the average current through the circuit was 100.5 mA, producing a voltage of 807.3 mV across the mystery-wire resistor.? Solving by Ohm’s law, the resistance worked out to 807.3 mV ÷ 100.5 mA = 8.033 Ohms.? Dividing by the length of wire (899 cm), that works out to a resistivity of 0.00893 Ohms/cm.? Converting to more conventional units, that’s 893 Ohms/1000 meters, or 272 Ohms/1000 ft.? By comparison, 18-gauge copper wire (closest to 0.975 mm dia), has a resistivity of 20.94 Ohms/1000 meters.? Bottom line, the “mystery wire” has a resistivity that is 43-times greater than that of similar-sized coper wire.? I tried a shorter length of wire, as well as different power supply voltages, and all of the resistivity measurements came out very close to 0.0089 Ohms/cm. ? For what it’s worth, the power dissipation through the 110-Ohm resistor was about 1.1 Watts, and about 0.08 Watts through the 900-cm length of wire.? With these low power dissipation values, there should have been minimal heating effects that could affect the resistance as the components heated up. ? I hope this helps? --? Ken ?
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From: GEOelectronics@...Sent: Thursday, January 30, 2020 10:14 AM To: [email protected]Subject: Re: [XRF] Ken's "Mystery Wire" ? Please do try to look up your resistance readings, we can compare them to my results. ?
|
Thanks for your? thoughts Ken. Yes for sure we know relative thickness is a factor both in pure bare metal XRF and especially in plated items.
The copper foil is measured to be .001" or 0.0254mm the zinc metal is 0.015"
Geo
----- Original Message ----- From: Ken Sejkora <kjsejkora@...> To: [email protected]Sent: Thu, 30 Jan 2020 10:29:04 -0500 (EST) Subject: Re: [XRF] 'Resolution' of XRF?
Thanks for the brain teaser, Geo.? Just a couple of guesses, and ideas for additional experiments.? My first inclination is that in your element ‘sandwich’, the copper foil was significantly thicker than the cladding on a penny coin, and was sufficiently thick to block some of the excitation photons from reaching the zinc foil, and then even more likely, blocking some (most?) of the “returning” emission X-rays from the zinc from reaching the detector.? At only single-digit keV energies, the mass attenuation coefficient of copper can be pretty large, and a millimeter of Cu may be sufficient to effectively block the 8.6 keV Zinc X-rays from getting through to the detector.? Presumably in a penny, the copper cladding would only be thick enough to give the coin a copper color, and much thinner than the zinc core in the center of the penny.? The copper cladding on the penny may be thin enough to allow some of the emission X-ray from the zinc? core? to get back to the detector, and yield the XRF spectrum indicative of both elements.? If the objective behind using a zinc core in a penny is to save copper, it would make sense that the copper clad would be as thin as possible, and the zinc core being much thicker.? Much thinner copper relative to your “sandwich” experiment would likely allow some of the zinc X-rays to make it to the detector. ? As for additional experiments, I’d like to see two more XRF scans.? First, a scan of the zinc foil on top of the copper foil, as opposed to your experiment which had the copper on top of the zinc.? I’d also like to know the thicknesses of your copper and zinc “stamps”.? The second experiment would be to repeat your first “sandwich” scan, except using a much thinner layer of copper foil over the zinc foil.? I guess even another experiment would be to adjust the angle of the “sandwich” relative to the incident excitation beam and/or detector plane to see if there are any effects of scatter angle, but I think that would be a stretch. ? I’ll be interested to see other people’s thoughts. ? Ken ?
Then the results of its XRF scan:
What conclusions can we draw from this failed test? "proof" and what further experiments can be added to this series?
Have fun
Geo>K0FF
|
Thanks for the brain teaser, Geo.? Just a couple of guesses, and ideas for additional experiments.? My first inclination is that in your element ‘sandwich’, the copper foil was significantly thicker than the cladding on a penny coin, and was sufficiently thick to block some of the excitation photons from reaching the zinc foil, and then even more likely, blocking some (most?) of the “returning” emission X-rays from the zinc from reaching the detector.? At only single-digit keV energies, the mass attenuation coefficient of copper can be pretty large, and a millimeter of Cu may be sufficient to effectively block the 8.6 keV Zinc X-rays from getting through to the detector.? Presumably in a penny, the copper cladding would only be thick enough to give the coin a copper color, and much thinner than the zinc core in the center of the penny.? The copper cladding on the penny may be thin enough to allow some of the emission X-ray from the zinc? core? to get back to the detector, and yield the XRF spectrum indicative of both elements.? If the objective behind using a zinc core in a penny is to save copper, it would make sense that the copper clad would be as thin as possible, and the zinc core being much thicker.? Much thinner copper relative to your “sandwich” experiment would likely allow some of the zinc X-rays to make it to the detector. ? As for additional experiments, I’d like to see two more XRF scans.? First, a scan of the zinc foil on top of the copper foil, as opposed to your experiment which had the copper on top of the zinc.? I’d also like to know the thicknesses of your copper and zinc “stamps”.? The second experiment would be to repeat your first “sandwich” scan, except using a much thinner layer of copper foil over the zinc foil.? I guess even another experiment would be to adjust the angle of the “sandwich” relative to the incident excitation beam and/or detector plane to see if there are any effects of scatter angle, but I think that would be a stretch. ? I’ll be interested to see other people’s thoughts. ? Ken ?
Then the results of its XRF scan:
What conclusions can we draw from this failed test? "proof" and what further experiments can be added to this series?
Have fun
Geo>K0FF
|
