Joe Gayo's Fusor - Neutron Detection Upgrade

Current images of fusor efforts, components, etc. Try to continuously update from your name, a current photo using edit function. Title post with your name once only. Change image and text as needed. See first posting for details.
Joe Gayo
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Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Joe Gayo » Wed Jan 16, 2019 4:44 am

Upgraded detection to BF3 tube with TC174 preamp
IMG_1025_sm.jpg
Clean detection pulse with shaping
IMG_1026_sm.jpg
90n/sec @ 27mTorr, 43kV, and 10mA
IMG_1041_sm.jpg

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Richard Hull
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Richard Hull » Wed Jan 16, 2019 5:39 am

Looks great with your new, far superior tube and windowing. Once again, tube in vs tube out data?
I think you are doing fusion. Let's see the comparison now.

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
Retired now...Doing only what I want and not what I should...every day is a saturday.

Joe Gayo
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Joe Gayo » Wed Jan 16, 2019 6:04 am

All done during the same run ...
27 mTorr D2
43 kV @ 11mA

90 sec (with moderator): 8186 counts
90 sec (no moderator or oven): 13 counts
90 sec (with moderator): 7993 counts

————————————
Activation Run:

4g Ag 0.5 mm Foil 0.15m distance in oven

300 sec @ 80-100n/sec

60 sec 141 counts
300 sec background avg 44

(Activation Edited: Previous math error)

Joe Gayo
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Joe Gayo » Wed Jan 16, 2019 6:18 pm

Adjusted the P/Z on the shaping amplifier to improve the return to zero (runs still consistent with previous measurements)

Next steps:
- Bubble dosimeter calibration
- Upgrade feedthrough and power supply to 70kV

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Richard Hull
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Richard Hull » Wed Jan 16, 2019 9:17 pm

Joe, welcome to the neutron club. What a difference with the 3He tube. over the Russian tube. As you have a gauge and have used both tubes. You might go back to assist everyone with a future Russian tube and give a report on how to get it to function even marginally for neutron detection.

Re-bias it so that the returns look close to your 3He tube or as close as possible.

Report the tube number, your bias, the input circuit component you used as you did before and what the differences between the x-ray component and the neutron components look like on the scope picture and how you might best window out non-neutronic responses in the tube.

I genuinely feel that the Russian tube is a good tube, but it just can't compete in the far more casual world of the 4 atmosphere 3He tube for ready and stunning results unless it is critically handled from the front end to the final windowing.

In your report give us a qualitative feel for both tube experiences you have had.

You may be the only person here who used both tubes and have a special perch to tweet from on this matter.

Thanks

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
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Dennis P Brown
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Dennis P Brown » Wed Jan 16, 2019 10:52 pm

Congratulations on really good work; few get both neutron detection via a tube and Ag activation for their first runs to join the neutron club.

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Richard Hull
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Richard Hull » Thu Jan 17, 2019 5:21 am

A great example of having the "right stuff", in two cases.... In the first case both Joe's carefully working, taking a bit of direction, learning and adjusting. The second case was obtaining the right stuff in that matched pre-amp and 3He tube and windowing it to perfection. That last run report was a classic study of what we love to see from the "tube-in vs. tube-out" acid test preformed in a virtually perfect detection setup and in good fusor operation, the latter he seemed to have already mastered as we dragged him through a lot of hoops. He now has the touch that few here ever master to the fullest degree.

I hope Joe never felt pressured or dis-believed. In the end it doesn't really matter what he felt, it is what he did. "He had guts and guts is enough" ...He won!

I hope he sticks around after his win. We can use another hands-on, "git er done", winner.

Oh, I assume he spent a bundle. That helps but, only up to a point

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
Retired now...Doing only what I want and not what I should...every day is a saturday.

Joe Gayo
Posts: 112
Joined: Mon Jan 07, 2019 2:34 am
Real name: Joe Gayo
Location: Los Angeles, CA

Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Joe Gayo » Thu Jan 17, 2019 6:39 am

Not surprisingly, Richard’s feedback was extremely valuable and provided the helpful nudge.

I feel as if the journey has just begun. Operational experience (and wall loading?) is pushing count rates higher and higher (140/sec last run), but I still need to calibrate with the bubble dosimeter. Activating silver seems easy and I want to setup a gamma spectrometer and run indium and manganese.

I built my 50kV supply with an inverter I designed and an old Glassman multiplier stack. Now I’m doing the same thing with a Spellman 70kV stack. My goal is 5M n/sec and to use it for real science (neutron optics, etc.)

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Dennis P Brown
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Dennis P Brown » Thu Jan 17, 2019 1:33 pm

I would think that your design for your 50 kV power supply would be a great post. You should consider that since that would be both useful and insightful for other people here. Also, maybe include your construction of your new 70 kV system, as well, as it progresses. Sharing methodologies and practices is what this forum is all about.

Joe Gayo
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Joe Gayo » Sat Jan 19, 2019 3:55 am

Just to be clear: my fusor only uses a dual stage rotary vane pump (Pfeiffer Duo 2.5) with a base pressure of 3mTorr.

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