Fusor 2020 Activation Experiments

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Mark Rowley
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Re: Fusor 2020 Activation Experiments

Post by Mark Rowley »

Thanks Jon, here’s a subsequent 3.75hr gamma spec of the same sample showing a much larger 511 photopeak.
C76AE72F-8192-4FE7-9435-CD42DA99B530.jpeg

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:
A8B5A772-61F2-441E-B879-6B859873DAE8.png
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Jon Rosenstiel
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Re: Fusor 2020 Activation Experiments

Post by Jon Rosenstiel »

Mark, I suspect your 1" x 1" piece of Mo will work fine.

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Richard Hull
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Re: Fusor 2020 Activation Experiments

Post by Richard Hull »

Great 511 annihilation peak!

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
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Mark Rowley
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Re: Fusor 2020 Activation Experiments

Post by Mark Rowley »

-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.

B3A10D81-F57A-433A-9694-D5D4B711F02E.jpeg


Here it is comfortably nestled within the HDPE moderator.

99119AC6-31BF-47A2-90BE-864DCE46A157.jpeg

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.

8A2163CC-343B-44D2-A1B1-20AFA4483F6A.jpeg
So that will be it for a few weeks till I get the power supply issue figured out.

Mark Rowley
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Richard Hull
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Re: Fusor 2020 Activation Experiments

Post by Richard Hull »

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
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
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Mark Rowley
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Re: Fusor 2020 Activation Experiments

Post by Mark Rowley »

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.

8ADE7A74-A668-466F-82DA-A0445340BB95.jpeg

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.

3CF6805B-6189-487C-9644-0BFCE364B810.jpeg

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.

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Jim Kovalchick
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Re: Fusor 2020 Activation Experiments

Post by Jim Kovalchick »

I bought a piece of that vanadium on ebay a month ago. You beat me to the activation! As always, nice work Mark.

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Richard Hull
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Re: Fusor 2020 Activation Experiments

Post by Richard Hull »

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
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
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Mark Rowley
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Re: Fusor 2020 Activation Experiments

Post by Mark Rowley »

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

5E4A5D3E-0E7F-4419-BEAE-CCEE95259C3D.jpeg
CD8746F9-4546-42CB-BE92-0826660DB1CA.jpeg
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Mark Rowley
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Re: Fusor 2020 Activation Experiments

Post by Mark Rowley »

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.
63E6A33C-33A5-4553-AA62-CFDA2B2E7B9A.jpeg

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.
BFD99929-A6D1-41A9-8C10-303E3E0934E6.jpeg
Molybdenum is the ultimate goal but will require some extra modifications to ensure the system can endure a 45minute to 1hr run time.

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Richard Hull
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Re: Fusor 2020 Activation Experiments

Post by Richard Hull »

Without sounding like a broken record.......Fabulous work! Kudos.

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
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