Neutrons!

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Garrett Young
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Re: Neutrons!

Post by Garrett Young » Thu Mar 30, 2017 1:59 am

Interesting. Thank you for sharing. I'll have to read more about their device.

Part of choosing the dimensions for my device was making sure child-langmuir space charge didn't limit the ion beam current.
- Garrett

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Garrett Young
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Re: Neutrons!

Post by Garrett Young » Tue Apr 04, 2017 3:01 am

Attempted a gamma spec of Indium (background removed). The signal to noise isn't great but that's probably due to the short activation time and low neutron numbers. In addition, it seems the detector is more sensitive to lower energy gammas. Does that make sense for a NaI crystal? Can Theremino MCA be calibrated for this variation in sensitivity using the energy equalizer?
ThereminoMCA_20170403_In.png
- Garrett

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Richard Hull
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Re: Neutrons!

Post by Richard Hull » Wed Apr 05, 2017 7:46 am

The lower end of NaI:Tl xtals are always a noise fest, as the background is a mix of low energy gammas, xrays and weakened cosmic interactions with local matter. The only thing you can background out are terrestrial NORM signals as they are present and rather constant. Random cosmic interactions are not so easy. Depending on the crystal size, low energy stuff, (noise in low energy end), is 100% captured in the xtal and makes a flash. Lots of clutter under 50kev and only a strong source will push out of it enough to be seen easily. Log mode energy display will often assist, but you will never have sharp peaks from and NaI:Tl crystal.

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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Garrett Young
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Re: Neutrons!

Post by Garrett Young » Mon May 01, 2017 12:25 am

Acquired a new power supply capable of -60kV and 11mA and have performed several lower power runs and the results are very exciting.

Pressure: 33 mTorr
Cathode Voltage: 44.1 kV
Cathode Current: 10.9 mA

TIER: 1.30 E+6 n/sec (!!)
Q: 3.16 E-9
- Garrett

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Steven Sesselmann
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Re: Neutrons!

Post by Steven Sesselmann » Mon May 01, 2017 1:38 am

Garrett,

Congratulations on reaching the mega neutron mark, well done.

My next target..

Steven
http://www.gammaspectacular.com - Gamma Spectrometry Systems
https://www.researchgate.net/profile/Steven_Sesselmann - Various papers and patents on RG

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Garrett Young
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Re: Neutrons!

Post by Garrett Young » Sat May 06, 2017 3:10 am

Thanks Steven.

I ran tonight with my rebuilt Spellman DXM70N600 (viewtopic.php?f=11&t=11146&start=146) and sustained >1 E+6 n/sec for a couple of minutes.

Though this performance may be standard for the stock 6 inch fusor, it seems this is several multiples above previous results from a compact fusor.
- Garrett

Andrew Seltzman
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Re: Neutrons!

Post by Andrew Seltzman » Sat May 06, 2017 3:54 am

I agree, there hasn't been(on this forum) a compact system with this output level. The compact system would allow a sample to be placed closer to the center allowing faster neutron activation.

I noticed you have a patent pending sticker on your custom inverter, was this built just for the spellman supply?
Andrew Seltzman
www.rtftechnologies.org

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Garrett Young
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Re: Neutrons!

Post by Garrett Young » Sat May 06, 2017 4:31 am

The custom inverter was designed/built especially for the Spellman DXM70N600 (and can be modified for other DXM models).

The "patent pending" label came printed on the extruded heatsink I'm using for the IGBTs. I'm not seeking a patent for the design, but if you wanted the operational ease of a x-ray transformer with the compactness/weight of a smps this is the way to do it. I have been thinking about designing a power supply especially for fusors. Targeting low cost and about 300W (40kV/7.5mA). The user would supply the variac and panel meters and I would provide the inverter and high voltage section.
- Garrett

RobertTubbs
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Re: Neutrons!

Post by RobertTubbs » Sat May 06, 2017 6:33 am

Really cool project Garrett, and nice work. This concept has been on my list of things to try as it functions much like a beam on target system would but with discharge mantained and directed by the central cathode. I ultimately opted for the persuit of monoatomic species of ions for their favorable qualities during bombardment. Your config here is an excellent, though not commonly discussed route to what basically amounts to a twin diatomic beamed beam-target arrangement. Your conditioning is the loading of deuterium into the materials on the two ends of the beams' axis. Though most documentation will say to use Ti for loading, you can use a Ti cathode and it'll sputter your vessel with an appropriate thickness of Ti during a bit of operation, just leave it in if you do this. Alternatively you can just use solid aluminum ends which perform twice as well as a thick (non-sputter layer thickness) piece of Ti. Either of these should increase your yields by a factor of some number.

This thread's ultra-premium quality is like something out of the early days of the forum.
RT

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Garrett Young
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Re: Neutrons!

Post by Garrett Young » Sun May 07, 2017 6:33 am

New personal best:

Cathode Voltage: 59.8 kV
Cathode Current: 8.5 mA
Pressure: 28 mTorr

TIER: 1.74 E+6
Q: 4.01 E-9
- Garrett

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