Proton Detectors?

It may be difficult to separate "theory" from "application," but let''s see if this helps facilitate the discussion.
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JuanDosio
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Proton Detectors?

Post by JuanDosio » Sat Nov 05, 2016 7:03 am

Hello everyone i have recently been looking into accurate data acquisition methods and was just wondering why no one seems to use proton detectors, which to my understanding are both more accurate and cheaper, given the fact that there are about as many protons shooting out of the fusor as there are neutrons.Im sure there must be a reason why this is and was wondering what the reasoning was. Thanks in advanced!

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JD

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Re: Proton Detectors?

Post by Grigory_Heaton » Sat Nov 05, 2016 4:48 pm

I'm not experienced with proton detectors, but I am almost certain that no useful amount of protons will be able to escape the fusor. Protons are still charged heavy particles, and charged heavy particles do not penetrate materials well at all. Even if you were using a glass jar design I doubt any detectable proton radiation would escape, much less with the common stainless steel designs. As a comparison, alpha radiation is Helium-4 nuclei and is stopped by a sheet of paper. Alphas have double the charge of a proton, but a proton will likely only get a few times further.

All that should be escaping a D-D fusor as a result of fusion are neutrons and the very rare gamma emission from the 1 in 10,000 He-4 production. The latter is essentially impossible to measure unless you are doing huge amounts of fusion, which is why everyone here goes with neutron detectors, as almost all neutrons will pass through the fusor walls as if it wasn't there due to their lack of charge.

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Richard Hull
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Re: Proton Detectors?

Post by Richard Hull » Sat Nov 05, 2016 5:51 pm

0.0000 protons will exit the fusor. 0.000 tritium nuclei will exit the fusor. 0.000 3He nuclei will exit the fusor. Neutrons will whistle through the steel shell like it is not there. In theory, if you are doing 100,000 fusions per second. 50,000 neutrons will shine through the shell each second and about 10 gamma rays. All will come out isotropically. Counting gammas is not an option. This leaves only neutrons as the countable entity.

Richard Hull
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Fusion is the energy of the future....and it always will be
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Re: Proton Detectors?

Post by John Futter » Sat Nov 05, 2016 6:13 pm

Juan
Although possible, damage to the SSD from neutrons would make it an expensive experiment.
SSD's also have a finite life from the damage cascades that the protons leave in the silicon as they enter. This shows up as leakage and noise as the damage increases.
And of course the SSD will be inside the chamber not outside making noise from the fusor electrics almost impossible to filter out

Dan Knapp
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Re: Proton Detectors?

Post by Dan Knapp » Sun Nov 06, 2016 4:08 am

The Wisconsin group has published work on detection of protons in a fusor using a semiconductor detector inside the vacuum chamber. I'll see if I can find the papers and post the references.

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Re: Proton Detectors?

Post by Grigory_Heaton » Sun Nov 06, 2016 5:26 am

Dan Knapp wrote:The Wisconsin group has published work on detection of protons in a fusor using a semiconductor detector inside the vacuum chamber. I'll see if I can find the papers and post the references.
My worry with this would be damage to the detector if used for too long. Outside the fusor there are no protons, but inside with a near-vacuum there should be quite a few high energy protons shooting out of the center.

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Re: Proton Detectors?

Post by JuanDosio » Sun Nov 06, 2016 8:12 am

What about within the chamber, if i recall correctly Doug Coulter has quite a big chamber and he does all of his fusion within a small branch of the fusor. Would it be efficient in a scenario like this?

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Richard Hull
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Re: Proton Detectors?

Post by Richard Hull » Sun Nov 06, 2016 5:49 pm

If you have the money for the silicon PIPS detector ($500.00 - $1000.00) and then the know-how and the electronics needed to filter the noise from within the fusor, let me know how all this works out for you after you ruin the detector.

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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Re: Proton Detectors?

Post by Dan Knapp » Sun Nov 06, 2016 9:54 pm

You can download a PDF of one of the Wisconsin papers describing proton detection at:
http://fti.neep.wisc.edu/pdf/fdm1144.pdf
They used a 25 micron lead foil to protect the PIPS detector from x-rays and alphas.

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