Silver activation with planar ring accelerator.

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Rich Gorski
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Silver activation with planar ring accelerator.

Post by Rich Gorski »

The silver activation signal shown in this report was created by the neutron flux from my planar ring accelerator device (fusor) with three circumferential planar ion sources. The device was running at 44kV, about 20mA current, a D2 pressure of 1 mTorr and with a 10 oz silver ingot receiving a 7 minute exposure at 21cm. The plots below show the raw data from the Ludlam M3 rate meter picking up the beta decay from the Ag109 -> Ag110 reaction. A conversion of this raw data into counts per minute appears next.

V = 44kV, P = 1mTorr, 7 minute exposure. D2 from PEM electrolyzed D2O
I PSU varied from 18mA to 21mA (3 circumferential ion sources running)
Neutron count: B10 tube at 21cm ~ 150 cnts/s
Isotropic neutron count rate from B10 = 8.3 x10^5 (cnts/s)
10 oz 99.99% silver bar placed against LND 7311 pancake detector
Reaction 109Ag (n,g) -> 110Ag T1/2 = 24.6s

Procedure:
A 10 oz silver bar (99.999 %) was placed in immediate contact with the LND 7311 pancake detector connected to a Ludlam M3 rate meter. The setup was enclosed in a 9” x 9” x 6” box of HDPE moderator and positioned 21 cm from the center of the vacuum chamber. A 7 minute exposure was completed, the main PSU switched off and the Ludlam M3 simultaneously switched on. After about 20 seconds of initial acquisition in the slow time constant mode the Ludlam peak out at about 176 counts/min which is near 4X higher than background. The M3 was in the slow time constant mode so the count would have been significantly higher if the initial counts near T = 0 could have been determined. However the activation signal is still quite obvious.
sag1.jpg
sag2.jpg

To prove that this is not some electronic issue with the detector the test was repeated using PEM electrolyzed H2 instead of D2. As the plot below shows there is no increase in the count rate above background at T = 0 indicating no activation as expected with H2.
sag3.jpg


View looking down into ring accelerator
Planar ring accelerator with three circumferential anode layer ion sources spaced 120 degrees apart. The ion sources are mounted on the interior wall of the cylindrical vacuum chamber. Three triangular shaped ion beams can be seen focusing at the center collision point (hot spot) in the center of the chamber. The circular ring is the final accelerating electrode that is connected to the main PSU and running at -44kV and appears to be glowing red hot from the near 900 watt input power. The three ion beam focus to a small point in the center and then pass through each other expanding on the opposite side. Snow in the photo is from X-ray photons on the CCD array.
sag4.jpg

The LND 7311 pancake detector setup is shown below immersed in HPDE moderator blocks along with some wax blocks. The silver ingot is the shiny object left of the detector. The detector is 21 cm from the center of the vacuum chamber where the hot plasma spot is located. Lead shielding can be seen covering the vacuum chamber on the right hand side.
sag5.jpg

Ludlam M3 rate meter, the LND 7311 pancake detector with thin mica window (good for beta) and the 10 oz silver ingot. The red and black wires leading from the M3 and connected to the scope probe connect directly to the terminals of the analog meter. This provides the count per minute analog output.
sag6.jpg
LAB PHOTOS
sag7.jpg
SAG8.jpg
sag9.jpg
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Richard Hull
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Re: Silver activation with planar ring accelerator.

Post by Richard Hull »

Rich, You are now placed in the elite neutron fusioneer status! You have used a unique and now proven fusor design and have proven you have activated silver. A fabulous job and an equally stunning and detailed report. This is how it is done!

Great images in an unkept, confused lab that indicates real labor being done in an unconfused, directed, goal orientated manner.......The hands on imperative at work.

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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Rich Gorski
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Real name: Rich Gorski
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Re: Silver activation with planar ring accelerator.

Post by Rich Gorski »

Richard,

Thanks for the kind words and the upgrade into the elite section of the neutron club. Your observation about the condition of my lab (unkept) is spot on... yes, a sign of activity going on at a constant pace. My plan for the future is to continue refining my device, run some other interesting tests where I will report on here and to monitor fusor.net to help out individuals where I can.

Rich G.
Alexey Khrushchev
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Re: Silver activation with planar ring accelerator.

Post by Alexey Khrushchev »

Remarkable work!
I wonder how thick is the lead in the shield and what is the X-ray level of the control desk at maximum voltage?
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Rich Gorski
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Re: Silver activation with planar ring accelerator.

Post by Rich Gorski »

Alexey,
Most of the lead sheet I'm using to block X-rays is 3mm thick although there are a few areas where the lead sheet is 1.5mm thick.

I'm not measuring much X-ray at the control desk as long as the lead sheet is in place. When above 30kV there is significant X-ray reflection/scattering off of metal surfaces nearby so I have to make sure the chamber is completely covered with the lead sheet. I have two means of measuring the X-ray flux;

1. Ludlam M3 GM rate meter: Max reading at the control desk was around 1.0 mR/hr when the fusor was at 35kV @ 15mA
2. Unfors 517L dosimeter: Max reading as I recall was around 0.02uGy/s

Both readings are quite low (as long as the lead shielding is present) and nothing to worry about if the fusor is run for only a few minutes once in a while.

Rich G.
Alexey Khrushchev
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Real name: Alexey Khrushchev
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Re: Silver activation with planar ring accelerator.

Post by Alexey Khrushchev »

Rich, thanks for the detailed response. You said that the dose rate at the control desk reaches 1.0 mR/hr, I think it is quite a lot, 50 times higher than the natural background. Maybe I'm a bit of a safety nut, but when I work my fusor, the dose rate at the control desk is only 0.06 mR/hr and I use a leaded rubber apron.
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Richard Hull
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Re: Silver activation with planar ring accelerator.

Post by Richard Hull »

Most fusors are run at full tilt 30kv @15ma for only about 5 minutes to avoid melting the grid. With 1 merm/hr that is ~.08 mrem total dose. A well made metal fusor will not really emit any radiation of significance at all at 25kv. I operate at 44kv @10ma for about 10 minutes. At the naked fusor shell that is about 6mrem/hr. No lead shielding other than at the view port and I record about 0.9mrem/hr at my seat some 6 feet away.

A charged and zero'd 0-100 mrem dosimeter in my shirt pocket never moves off zero to my eye. That 0.9mrem/hr is read with a victoreen ion chamber in my lap with no shielding at all while seated at the control panel. This doses me with 0.09mrem during the run. No problem. I operate my fusor about 20 times per year at this level for a total dose of 1.8 mrem. No problem at all since the average dose for most non-fusor folks grab 200 mrem/year. Another 2 mrem/year is nothing compared to just living on earth for a year.

Just because you have a fusor idling at 23kv with plasma before a run up for 30 minutes doesn't mean you are getting dosed at all!

Short times of operation at full, max output and distance are as good a lead shielding any day.

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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