Fusor 2020 Activation Experiments
- Mark Rowley
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Re: Fusor 2020 Activation Experiments
-Manganese 56-
Since 2009 I’ve always been impressed with the Manganese activation experiment conducted by Carl Willis (https://youtu.be/ng6NOH8S7Bk). I’ve attempted it with weak static sources with no luck. Since the fusor has been operating fairly good lately I gave it a shot exposing a small 1.2” puck of manganese dioxide for 5 minutes at a neutron TIER of roughly 1.7E+6.
Once complete, it was quickly put in the gamma spectrometer which instantly displayed a strong 850keV photopeak.
Time lapse MCA spectra acquisition of 2000 seconds can be seen here.
https://youtu.be/AfX5w53ZB1s
Since 2009 I’ve always been impressed with the Manganese activation experiment conducted by Carl Willis (https://youtu.be/ng6NOH8S7Bk). I’ve attempted it with weak static sources with no luck. Since the fusor has been operating fairly good lately I gave it a shot exposing a small 1.2” puck of manganese dioxide for 5 minutes at a neutron TIER of roughly 1.7E+6.
Once complete, it was quickly put in the gamma spectrometer which instantly displayed a strong 850keV photopeak.
Time lapse MCA spectra acquisition of 2000 seconds can be seen here.
https://youtu.be/AfX5w53ZB1s
- Richard Hull
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Re: Fusor 2020 Activation Experiments
Fabulous work Mark! I have to get my numbers way up before I get to manganese activation. I remember Carl used the sulfate dissolved in a gallon jug. The water was the moderator as well with the saturated solution of manganese sulfate. That was really cool....A two fer...
Richard Hull
Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
- Mark Rowley
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Re: Fusor 2020 Activation Experiments
-Copper 66-
This has been a tough nut to crack. I got some promising results this afternoon but nowhere near the nice photopeak I had with Mn56. To do so would’ve required a good 10+ minutes of flux time at the same neutron numbers (or higher) as I did with Manganese. Unfortunately at 1.5 to 2E+06 I’m limited to under 5 minutes due to chamber heating. Today’s copper activation experiment resulted in 3.5 minutes of activation time at an approximate neutron TIER 2E+06. I shut off the activation run when the chamber hit a surface temp of 160F.
-Gamma Spec Results-
For both background and the 1x1.5” copper plate specimen,count times were 1500 seconds respectively.
Normal background in the lead gamma spec castle was 3.0cps with a 1.5x2.25” NaI(TI) Bicron pmt.
The copper specimen registered 6.8cps when initially placed in the chamber. After 500 seconds it decayed to 4cps and at 900 seconds, 3.8cps. By 1500s seconds it was at 3.3cps.
Photopeaks at 511keV and 1040keV can be clearly seen. When equivalent background is subtracted, the 1040keV peak is more pronounced and the 511keV Is reduced by the removal of the natural lead induced photopeak at the same energy.
Total background counts:4592
Total counts with activated copper: 5575
Total counts over background: 983
I referenced Carl and Jon’s 15 year old copper activation experiment for general guidance.Their excellent report can be seen here:
viewtopic.php?f=13&t=5607&p=37584&hilit ... ion#p37584
A time lapse video of the gamma spec run can be seen here. Due to camera issues, it’s only 900 seconds of the 1500sec run.
https://youtu.be/xD3GXA-_Oqw
This is the copper sandwiched between HDPE slabs. The copper plate is exactly 17cm from the grid.
Lead Castle,Activated Copper Plate and PMT
Once I get the cooling issue resolved I’ll try again for larger photopeaks.
Mark Rowley
This has been a tough nut to crack. I got some promising results this afternoon but nowhere near the nice photopeak I had with Mn56. To do so would’ve required a good 10+ minutes of flux time at the same neutron numbers (or higher) as I did with Manganese. Unfortunately at 1.5 to 2E+06 I’m limited to under 5 minutes due to chamber heating. Today’s copper activation experiment resulted in 3.5 minutes of activation time at an approximate neutron TIER 2E+06. I shut off the activation run when the chamber hit a surface temp of 160F.
-Gamma Spec Results-
For both background and the 1x1.5” copper plate specimen,count times were 1500 seconds respectively.
Normal background in the lead gamma spec castle was 3.0cps with a 1.5x2.25” NaI(TI) Bicron pmt.
The copper specimen registered 6.8cps when initially placed in the chamber. After 500 seconds it decayed to 4cps and at 900 seconds, 3.8cps. By 1500s seconds it was at 3.3cps.
Photopeaks at 511keV and 1040keV can be clearly seen. When equivalent background is subtracted, the 1040keV peak is more pronounced and the 511keV Is reduced by the removal of the natural lead induced photopeak at the same energy.
Total background counts:4592
Total counts with activated copper: 5575
Total counts over background: 983
I referenced Carl and Jon’s 15 year old copper activation experiment for general guidance.Their excellent report can be seen here:
viewtopic.php?f=13&t=5607&p=37584&hilit ... ion#p37584
A time lapse video of the gamma spec run can be seen here. Due to camera issues, it’s only 900 seconds of the 1500sec run.
https://youtu.be/xD3GXA-_Oqw
This is the copper sandwiched between HDPE slabs. The copper plate is exactly 17cm from the grid.
Lead Castle,Activated Copper Plate and PMT
Once I get the cooling issue resolved I’ll try again for larger photopeaks.
Mark Rowley
- Richard Hull
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Re: Fusor 2020 Activation Experiments
Wow! You got copper to give it up! Great work and great fusor!
Richard Hull
Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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- Real name: Jon Rosenstiel
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Re: Fusor 2020 Activation Experiments
Great results with the copper, Mark. I think you’re close to being able to activate aluminum.
Jon Rosenstiel
Jon Rosenstiel
- Mark Rowley
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Re: Fusor 2020 Activation Experiments
Thanks!
Hmmmm, you piqued my interest Jon. Background noise in the 1.78meV region of the gamma spec system is comparatively nil, just natural K40 at 1.46meV. This should assist with detecting a low yield activation, which no doubt would be the case.
If I can get the cooling under control for a solid 5 minutes, I’ll give it a shot.
Mark Rowley
Hmmmm, you piqued my interest Jon. Background noise in the 1.78meV region of the gamma spec system is comparatively nil, just natural K40 at 1.46meV. This should assist with detecting a low yield activation, which no doubt would be the case.
If I can get the cooling under control for a solid 5 minutes, I’ll give it a shot.
Mark Rowley
- Mark Rowley
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Re: Fusor 2020 Activation Experiments
Today’s run activated a small amount of aluminum powder to create the short lived isotope of Al28. This isotope has a gamma energy of 1.78MeV.
The activation consisted of a 10 minute exposure to a roughly estimated neutron TIER of 1.5E+6. During this time a small sachet of aluminum powder(pictured) was situated in an HDPE moderator 17cm from the fusor grid.
Following activation, the aluminum sample was quickly placed in the gamma spectrometer lead castle for a 606 second assessment run. Almost immediately a distinguishable photopeak was evident at the expected Al28 gamma energy of 1.78MeV. Just to the left the natural K40 peak can be seen at 1.46MeV.
Total counts during the 606 second run was 2377.
I conducted three background counts using the same time span. They were 1875, 1856, and 1889. Using 1875 as the average, the activated assessment registered 502 counts over background.
When the aluminum sample was placed in the spectrometer, it averaged approximately 7cps and decayed to 3.9cps after 606 seconds. An hour afterwards the sample was indistinguishable from normal background (~3cps).
Once again, many thanks to Jon R for sharing the cooling maze modification. This 10 minute run never peaked over 24 deg Celsius!
Mark Rowley
The activation consisted of a 10 minute exposure to a roughly estimated neutron TIER of 1.5E+6. During this time a small sachet of aluminum powder(pictured) was situated in an HDPE moderator 17cm from the fusor grid.
Following activation, the aluminum sample was quickly placed in the gamma spectrometer lead castle for a 606 second assessment run. Almost immediately a distinguishable photopeak was evident at the expected Al28 gamma energy of 1.78MeV. Just to the left the natural K40 peak can be seen at 1.46MeV.
Total counts during the 606 second run was 2377.
I conducted three background counts using the same time span. They were 1875, 1856, and 1889. Using 1875 as the average, the activated assessment registered 502 counts over background.
When the aluminum sample was placed in the spectrometer, it averaged approximately 7cps and decayed to 3.9cps after 606 seconds. An hour afterwards the sample was indistinguishable from normal background (~3cps).
Once again, many thanks to Jon R for sharing the cooling maze modification. This 10 minute run never peaked over 24 deg Celsius!
Mark Rowley
- Richard Hull
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Re: Fusor 2020 Activation Experiments
Mark, you are becoming the activation hero!
I have a great Canberra gamma spec, but prefer the instant gratification of a beta activation where an embedded GM counter is the best for demo work before a group of spectators. As the fusor lab is unheated, my valuable 3 and 5-inch NaI:Tl Bircon heads and gamma spec system is located upstairs in my heated home. In spite of having the nice gamma spec system I have never once used it on any activation over the last 15 years of activation work! Figure that one out! I tend to use it to sniff out rock samples and the relative amounts of various natural radio nuclides.
Great work and I love the continuing efforts on your part and fabulous detailed reports.
Richard Hull
I have a great Canberra gamma spec, but prefer the instant gratification of a beta activation where an embedded GM counter is the best for demo work before a group of spectators. As the fusor lab is unheated, my valuable 3 and 5-inch NaI:Tl Bircon heads and gamma spec system is located upstairs in my heated home. In spite of having the nice gamma spec system I have never once used it on any activation over the last 15 years of activation work! Figure that one out! I tend to use it to sniff out rock samples and the relative amounts of various natural radio nuclides.
Great work and I love the continuing efforts on your part and fabulous detailed reports.
Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
- Mark Rowley
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Re: Fusor 2020 Activation Experiments
Thanks Richard
Knowing that I only had about 2.5 minutes with it’s half life, in short order I had to this:
Turn off the fusor
Turn off the fuel supply
Disassemble the moderator
Remove the irradiated sample
RUN to the house from the backyard lab
Put it in the spectrometer
Stack a few lead bricks
And turn on the spectrometer
In all that wasted time I lost a significant portion of it initial activation to necessary chores. Doubt I’ll ever move the spectrometry system into the shop.
Like you, I do enjoy silver and indium. Silver’s instant flurry of beta decay totally sends a nice message to visitors. I recently activated some sterling Ag items for some folks showing their subsequent activity with a TBM-3S pancake unit. Fun and undeniable results. Reminds me of the old irradiated dimes from the 1965 worlds fair.
Not sure what’s left to activate but for now my only remaining goal is to get a larger photopeak from Cu66 at 1.4MeV.
Suggestions are welcome!
Mark Rowley
Knowing that I only had about 2.5 minutes with it’s half life, in short order I had to this:
Turn off the fusor
Turn off the fuel supply
Disassemble the moderator
Remove the irradiated sample
RUN to the house from the backyard lab
Put it in the spectrometer
Stack a few lead bricks
And turn on the spectrometer
In all that wasted time I lost a significant portion of it initial activation to necessary chores. Doubt I’ll ever move the spectrometry system into the shop.
Like you, I do enjoy silver and indium. Silver’s instant flurry of beta decay totally sends a nice message to visitors. I recently activated some sterling Ag items for some folks showing their subsequent activity with a TBM-3S pancake unit. Fun and undeniable results. Reminds me of the old irradiated dimes from the 1965 worlds fair.
Not sure what’s left to activate but for now my only remaining goal is to get a larger photopeak from Cu66 at 1.4MeV.
Suggestions are welcome!
Mark Rowley
- Richard Hull
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Re: Fusor 2020 Activation Experiments
As you know, and as I have told it, Even in my lab, I had to race to the lab NIM bin counter for silver measurements in the past. Thus, my custom Arduino counting system and moderator-embedded GM detector on Fusor V.
Copper is a bold stroke by any measure. Cut time by pre-starting your gamma spec. open doors and warn the wife you are coming through at high speed. You could even have an assistant press the collect button the minute they here you rush into the house. You won't foul the collection by having it run a few seconds before you arrive Have every thing set for speed. Cutting a number of seconds off the dash will really help. Don't trip in the dash and fall, it ain't worth it.
Richard Hull
Copper is a bold stroke by any measure. Cut time by pre-starting your gamma spec. open doors and warn the wife you are coming through at high speed. You could even have an assistant press the collect button the minute they here you rush into the house. You won't foul the collection by having it run a few seconds before you arrive Have every thing set for speed. Cutting a number of seconds off the dash will really help. Don't trip in the dash and fall, it ain't worth it.
Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Re: Fusor 2020 Activation Experiments
Mark,
As to your copper count conundrum, maybe try copper metal powder in a Marinelli beaker. I think they run somewhere around $15.00 each.
https://www.drct.com/dss/accessories/be ... eakers.htm.
Jon R
As to your copper count conundrum, maybe try copper metal powder in a Marinelli beaker. I think they run somewhere around $15.00 each.
https://www.drct.com/dss/accessories/be ... eakers.htm.
Jon R
- Mark Rowley
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Re: Fusor 2020 Activation Experiments
Hi Jon,
Not a bad idea. The site looks like a good overall resource too!
I’ve yet to give the copper bar a nice long exposure with the new cooling system. Tonight or tomorrow I’ll flux it with a good 15 minute run and see what turns up. Stay tuned!
Mark Rowley
Not a bad idea. The site looks like a good overall resource too!
I’ve yet to give the copper bar a nice long exposure with the new cooling system. Tonight or tomorrow I’ll flux it with a good 15 minute run and see what turns up. Stay tuned!
Mark Rowley
- Mark Rowley
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Re: Fusor 2020 Activation Experiments
Much better results with Copper activation. 10 minutes of flux time at a rough TIER estimate of 1.7E+6 n/s.
The Cu66 photopeak at 1.04MeV is very pronounced at 346 seconds.
At 1000 seconds shown with natural background in gray.
This is a 1000 second natural background count with a non-irradiated copper sample of the same size.
Total counts from irradiated sample: 5039
Total counts from non-irradiated sample: 3298
Total counts over background: 1741
Mark Rowley
The Cu66 photopeak at 1.04MeV is very pronounced at 346 seconds.
At 1000 seconds shown with natural background in gray.
This is a 1000 second natural background count with a non-irradiated copper sample of the same size.
Total counts from irradiated sample: 5039
Total counts from non-irradiated sample: 3298
Total counts over background: 1741
Mark Rowley
- Mark Rowley
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Re: Fusor 2020 Activation Experiments
More progress with Copper activation today. The chart shows results after 533 seconds in the spectrometer. The 1.04MeV photopeak decayed to about nothing after 90 minutes however the 511keV is still cranking out gammas well above the natural artifact.
Flux time was 10 minutes.
Mark Rowley
Flux time was 10 minutes.
Mark Rowley
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Re: Fusor 2020 Activation Experiments
Way cool Mark,12.7-hour Cu-64 spittin’ out the positrons. Just think how large that 511 peak would be if you could activate your copper sample for 24-hours.
Jon Rosenstiel
Jon Rosenstiel
- Mark Rowley
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Re: Fusor 2020 Activation Experiments
Thanks Jon, here’s a subsequent 3.75hr gamma spec of the same sample showing a much larger 511 photopeak.
On that note I’m working on getting a sustained 1hr flux time so I can take a crack at your Molybdenum / Tc99m run a few years back.
viewtopic.php?t=5817
I have a small sheet of 1x1” of 99% Molybdenum however I noticed yours was more like a heavy billet. Will my attempt suffer or totally fail from the comparative thinness?
Here’s a pic of what I have on hand:
Mark Rowley
On that note I’m working on getting a sustained 1hr flux time so I can take a crack at your Molybdenum / Tc99m run a few years back.
viewtopic.php?t=5817
I have a small sheet of 1x1” of 99% Molybdenum however I noticed yours was more like a heavy billet. Will my attempt suffer or totally fail from the comparative thinness?
Here’s a pic of what I have on hand:
Mark Rowley
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Re: Fusor 2020 Activation Experiments
Mark, I suspect your 1" x 1" piece of Mo will work fine.
JonR
JonR
- Richard Hull
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Re: Fusor 2020 Activation Experiments
Great 511 annihilation peak!
Richard Hull
Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
- Mark Rowley
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Re: Fusor 2020 Activation Experiments
-Iodine Activation-
Subjected approx 30 grams of pure iodine prills to about 2.5 minutes of flux time at approx 6E+06 TIER n/s at 17cm distance.
Here it is comfortably nestled within the HDPE moderator.
So the plan was to zap this for a full 15 minutes so I could get not only the main activation product at 441keV but also the lesser one at 528keV. Unfortunately that didn’t work out due to operator error. Being that I’ve been conditioning my fusor the past 4 days I was overly elated to see my neutron count hovering in the 6E+06 range! So I added a tad more deuterium which caused a spike in current draw. That instantly put the precip power supply into some type of fault mode or failure where it’s only supplying 50% of its rated output. I’ve yet to dig into to the supply but when I do I’ll start a new topic or add it to one of the old ones.
Anyhoo, I decided to throw the 2.5 minute activated Iodine in the spectrometer. It was nice to see the decay product at 441keV but not a peep from the 528keV.
So that will be it for a few weeks till I get the power supply issue figured out.
Mark Rowley
Subjected approx 30 grams of pure iodine prills to about 2.5 minutes of flux time at approx 6E+06 TIER n/s at 17cm distance.
Here it is comfortably nestled within the HDPE moderator.
So the plan was to zap this for a full 15 minutes so I could get not only the main activation product at 441keV but also the lesser one at 528keV. Unfortunately that didn’t work out due to operator error. Being that I’ve been conditioning my fusor the past 4 days I was overly elated to see my neutron count hovering in the 6E+06 range! So I added a tad more deuterium which caused a spike in current draw. That instantly put the precip power supply into some type of fault mode or failure where it’s only supplying 50% of its rated output. I’ve yet to dig into to the supply but when I do I’ll start a new topic or add it to one of the old ones.
Anyhoo, I decided to throw the 2.5 minute activated Iodine in the spectrometer. It was nice to see the decay product at 441keV but not a peep from the 528keV.
So that will be it for a few weeks till I get the power supply issue figured out.
Mark Rowley
- Richard Hull
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Re: Fusor 2020 Activation Experiments
Getting great result on the activation. Mark, you have probably activated more stuff than any one here, Keep up the good work and incredible neutron numbers.
Richard Hull
Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
- Mark Rowley
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Re: Fusor 2020 Activation Experiments
Thanks Richard. Fusoring and gamma spec is quite the mix!
After repairing the power supply I elected to try activating Vanadium. Figured it’d be better to go for a new element in the case I had another unexpected power supply issue. Happy to report that wasn't the case.
The vanadium sample was a 9.5g 5x10cm sheet at 99.98% purity.
This sample was fluxed at roughly 2E+06 n/s TIER for 12 minutes. Far cry from the numbers I had last week but I’m not going to press my luck. Best to take it easy. Spacing from the grid was 17cm.
Once it hit the spectrometer it registered 15.1 cps.
200 seconds: 12.1 cps
1000 seconds: 6.9 cps
2000 seconds: 5.1 cps
The expected photopeak at 1434keV was immediately apparent once the spectrometer started its run.
Since the fusor was down for repairs most of my wall loading had gone away. However, I’ll try building it back up again for a couple days in hopes of getting a better gamma spec of iodine. The 528keV photopeak was missing but I think a good 15 minute exposure at higher numbers should remedy that.
Mark Rowley
After repairing the power supply I elected to try activating Vanadium. Figured it’d be better to go for a new element in the case I had another unexpected power supply issue. Happy to report that wasn't the case.
The vanadium sample was a 9.5g 5x10cm sheet at 99.98% purity.
This sample was fluxed at roughly 2E+06 n/s TIER for 12 minutes. Far cry from the numbers I had last week but I’m not going to press my luck. Best to take it easy. Spacing from the grid was 17cm.
Once it hit the spectrometer it registered 15.1 cps.
200 seconds: 12.1 cps
1000 seconds: 6.9 cps
2000 seconds: 5.1 cps
The expected photopeak at 1434keV was immediately apparent once the spectrometer started its run.
Since the fusor was down for repairs most of my wall loading had gone away. However, I’ll try building it back up again for a couple days in hopes of getting a better gamma spec of iodine. The 528keV photopeak was missing but I think a good 15 minute exposure at higher numbers should remedy that.
Mark Rowley
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Re: Fusor 2020 Activation Experiments
I bought a piece of that vanadium on ebay a month ago. You beat me to the activation! As always, nice work Mark.
Jim K
Jim K
- Richard Hull
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Re: Fusor 2020 Activation Experiments
Indeed, fabulous work! I have added you to the elite fusioneers touting your multi-element continuous activation. Great work and a seeming non-stop effort.
Richard Hull
Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
- Mark Rowley
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Re: Fusor 2020 Activation Experiments
I’m running out of things to activate! lol. Gadolinium seems like something fun to experiment with, at least in the neutron detector department.
Tonight’s run was a 15 minute Iodine activation at roughly 2.8E+06 n/s TIER. Compared to the ill fated first attempt (Nov 12th) which was abruptly stopped after the first couple minutes, this one resulted with a much stronger peak at 441keV. The peak at 528keV is still elusive, however when background was subtracted a small peak (or possibly noise) was near the 528keV region. Fwiw, after another 1000 seconds in the spectrometer the peak had decayed to zero but I’m still not really convinced.
It’s also likely that my spectrometer resolution is not good enough to isolate such a small photopeak so close to the wide base of the 411keV photopeak. As pointed out by Carl Willis in his Iodine activation report from years earlier, the 528keV accounts for a minuscule 1.5% of decays while the 411keV a whopping 14%. That’s a tiny blip to isolate with a crude NaI(TI) spectrometer. This actually highlights my concern with attempting a Molybdenum activation. Any hint of TC99m (140keV) will be very small and nudged up against or enveloped by the the wide base of the natural lead XRF peak at around 90kev. Background subtraction on Theremino MCA has a tendency to leave a bunch of xrf noise.
Regarding the iodine, maybe it just needs more neuts thrown at it! I may revisit this one again in the future.
Mark Rowley
Tonight’s run was a 15 minute Iodine activation at roughly 2.8E+06 n/s TIER. Compared to the ill fated first attempt (Nov 12th) which was abruptly stopped after the first couple minutes, this one resulted with a much stronger peak at 441keV. The peak at 528keV is still elusive, however when background was subtracted a small peak (or possibly noise) was near the 528keV region. Fwiw, after another 1000 seconds in the spectrometer the peak had decayed to zero but I’m still not really convinced.
It’s also likely that my spectrometer resolution is not good enough to isolate such a small photopeak so close to the wide base of the 411keV photopeak. As pointed out by Carl Willis in his Iodine activation report from years earlier, the 528keV accounts for a minuscule 1.5% of decays while the 411keV a whopping 14%. That’s a tiny blip to isolate with a crude NaI(TI) spectrometer. This actually highlights my concern with attempting a Molybdenum activation. Any hint of TC99m (140keV) will be very small and nudged up against or enveloped by the the wide base of the natural lead XRF peak at around 90kev. Background subtraction on Theremino MCA has a tendency to leave a bunch of xrf noise.
Regarding the iodine, maybe it just needs more neuts thrown at it! I may revisit this one again in the future.
Mark Rowley
- Mark Rowley
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- Real name: Mark Rowley
- Location: Sacramento California
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Re: Fusor 2020 Activation Experiments
Aside from silver, this marks the first substantial activation with the newly constructed flyback power supply (viewtopic.php?f=11&t=13907). In this test, the same puck of manganese used in last August’s test was used today.
At approximately 1.2E+6 n/s, the sample was fluxed for 5 minutes at a distance of 18cm from the grid. Moderator was HDPE.
As before, the MCA arrangement is Theremino with a Bicron scintillation probe. The 850keV photopeak was readily apparent within a second or two of activating the MCA.
Molybdenum is the ultimate goal but will require some extra modifications to ensure the system can endure a 45minute to 1hr run time.
Mark Rowley
At approximately 1.2E+6 n/s, the sample was fluxed for 5 minutes at a distance of 18cm from the grid. Moderator was HDPE.
As before, the MCA arrangement is Theremino with a Bicron scintillation probe. The 850keV photopeak was readily apparent within a second or two of activating the MCA.
Molybdenum is the ultimate goal but will require some extra modifications to ensure the system can endure a 45minute to 1hr run time.
Mark Rowley