Bremsstrahlung Radiation Detection

[Rex Allers]

For a cheap but effective MCA, here's a link to to a popular Italian project.
http://www.theremino.com/downloads/radioactivity

I haven't used it myself but have seen others' good results posted. It is based on getting the signal input through a decent sound card. The software is free for download. If you browse around the links on the page above, they have a design for a simple interface board to power the PMT and do initial processing of the signal. I think you can buy the board too.

You still need to find yourself a probe (crystal/PMT combination). NaI(Tl) is probably the most common and available crystal for gamma spectrometry. If opened to air the NaI is very hygroscopic and absorbed water will destroy it. Just a warning that some of the stuff you find on eBay may not be good.

The Gammaspectrometry group on Yahoo Groups is probably one of the most accessible places to start acquiring basic knowledge.

[Richard Hull]

Pure uranium in a fusor would fission, not activate. It has been tried and no one detected activation and fission detection would be difficult to detect without special internal sensors. There is just not enough neutron flux to do enough fission for easy detection or make good measurements with amateur equipment.

Uranium glass would most likely glow from UV Fluoresence. XRF data would be lost due to the shell, unless an internal sensor capable of detecting it were used. Even then the internal X-ray continuum might overpower the signal. There is only a tiny U mass in Uglass. Pure U would be the thing or a crystal of solid uraninite.

Still, no one would do this here as maybe only 3 people have the gear needed and they have been here long enough to read Carl Willis' report on the matter.

Richard Hull

[RealBorg]

With activation I meant increased radiation due to fission products, not as in neutron capture.

Of course you would have to shield the uranium glass against the UV radiation, but given it's reaction to UV radiation and the amount of low energy x-ray produced in a fusor the result should be impressive.

Tom

[Richard Hull]

Again, there will be no radiation due to fission products as the flux is not significant enough to produce enough fission products to be readily detectable once removed. It has been tried by one of our best fusioneers with good gear.

Richard Hull

[Dan Tibbets]

If this threat is still active a perspective may be gained from this PDF. EMC2 measured Bremsstruhlung radiation in order to demonstrate what is called the Wiffle Ball effect. Initially the filtered x-ray output was low- buried in the noise floor, only after the density of electrons above a KE of 2000 eV increased was a signal achieved. There are reasons why the X-ray origins were from Bremsstruhlung, rather than electron - wall impacts, mostly, I think, from sensor geometry relative to the plasma, and the dynamics expected as the plasma confinement and thus density increased while the high energy (above 2000eV) electron input was constant. I don't know if these situations could be obtainable in a glow discharge fusor or even an ion gunned fusor. Without this dynamic I'm uncertain how Bremsstruhlung x-rays could be distinguished from electron - wall origins. I suspect this second source of X-rays dominates unless, as is paramount in this study, the energetic electron confinement can be pushed to where the Bremsstruhlung sourced x-rays can become dominate, or at least prevalent enough that the signal can be massaged to get convincing results.

http://arxiv.org/pdf/1406.0133v1.pdf

Dan Tibbets

[Reid Byron]

Speaking of economic and effective sound card MCA's the gamma spectacular may work wonderfully for the experiments you are trying to do.

http://www.gammaspectacular.com/gamma-s ... ry-drivers


and to my knowledge was developed by someone on this forum, which is very cool.

[Tom McCarthy]

Thanks for the bump on the thread, Dan and Reid.

Dan,
I've taken a quick scan through the EMC2 paper..It seems to be mainly about the Polywell in general with very little on the actual Bremsstrahlung detection (that's just from a quick look, correct me if I'm wrong), I'll search around for related papers when I get a chance. Nonetheless, thanks for supplying the link.

Reid,
I have a GS-2000-PRO Gamma Spectacular system for neutron detection (with He-3 tube). Steven's a great guy to work with and if you're looking for something of that nature, I'd absolutely recommend Steven's wares. At the moment, I'm putting together a PMT set-up, but I haven't been able to get a NaI(Tl) crystal yet...I have a Hamamatsu R6233-05 PMT with a 76mm diameter face, so I'm looking for a 3" crystal. I'm not well versed in the details of PMT set-up, but I'm working towards it.

Cheers,
Tom