CHM-14 Neutron counter troubleshooting

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Ibrahim A Ozcan
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Re: CHM-14 Neutron counter troubleshooting

Post by Ibrahim A Ozcan »

Will investing in a more expensive detection system, an example being the likes of the "dragonfly", would combat this issue to some extent?, having more control over the tube and pulses would mean I could drown out pulses from other sources. Would you say a system like this is worth the price?
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Dennis P Brown
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Re: CHM-14 Neutron counter troubleshooting

Post by Dennis P Brown »

Fusors are giant noise producing machines. You suspect your setup but as some have suggested your detector tube might be the issue. Also, shielding on your system - is the base of your detector tube in the copper tube electrically sealed?
Ibrahim A Ozcan
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Re: CHM-14 Neutron counter troubleshooting

Post by Ibrahim A Ozcan »

what do you mean by electrically sealed? It is covered.
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Dennis P Brown
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Re: CHM-14 Neutron counter troubleshooting

Post by Dennis P Brown »

Blocking stray electric noise is difficult. Are both ends of the copper tube electrically sealed so the detector tube is fully isolated? From the picture I can not tell if the location where the cable connects to the detector tube is also electrically sealed - i.e. a solid metal barrier?
Ibrahim A Ozcan
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Re: CHM-14 Neutron counter troubleshooting

Post by Ibrahim A Ozcan »

The end is inside the copper tube, and the exterior is wrapped in copper tape and some painter tape (I was just testing the rig out before finalising everything)
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Dennis P Brown
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Re: CHM-14 Neutron counter troubleshooting

Post by Dennis P Brown »

Well, not sure if electrical noise is your main issue. But that arrangement for the connector cable and detector does not appear to be a good seal to prevent stray RF. But again, maybe a non-issue anyway.

Even copper tape can have issues blocking RF since it is not an electrical conductor due to the adhesive layer. Through it is superior to no seal.
Ibrahim A Ozcan
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Real name: Ibrahim Ali Ozcan

Re: CHM-14 Neutron counter troubleshooting

Post by Ibrahim A Ozcan »

how would you recommend i protect the connection then?
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Dennis P Brown
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Re: CHM-14 Neutron counter troubleshooting

Post by Dennis P Brown »

Well, I'm not certain at all that this is the source of your issues. But if you want to do a better RF seal, use a metal cap that makes tight physical contact with the copper tube (both ends). Drill a hole in one cap and use a proper coaxial cable connector that can be screwed down tight. This will both electrically and physically protect the detector tube.

I'll add that partial electrical shield is essentially no shielding. A copper tube with no electrically sealed end caps provide no significant shielding against stray RF (maybe improved x-ray blocking through.) Any open end allows RF to enter.

Again, I'm not fully convinced this is really required but it can't hurt. Certainly my He-3 tube didn't care when I used my Ludlum 2000 unit and a std coaxial HV cable. But when I built a rack using a special preamp, ground loops did bring in stray RF (my turbo was terrible in that respect) and this was a real problem. So, I have mixed results and can't really tell you whether your setup has any of these problems. Eliminating a possible problem is a good idea but this step does add complexity and work.
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Richard Hull
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Re: CHM-14 Neutron counter troubleshooting

Post by Richard Hull »

Corona with its associated RFI, EMI, and all x-rays from a fusor are all nothing but noise that must be dialed out of any neutron detection system.
The choice of, and electronic shepherding of any neutron detection tube are key in neutron only detection. Bias is just one part of this effort. Discrimination is the other part.

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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