Lithium Detection

This area is for discussions involving any fusion related radiation metrology issues. Neutrons are the key signature of fusion, but other radiations are of interest to the amateur fusioneer as well.
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Captain_Proton
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Lithium Detection

Post by Captain_Proton »

If I'm not mistaken, He4 (1.7MeV) and He3 (2.3 MeV) can fuse to form Li6 and a proton.
Shouldn't this be detectable with an RGA if pressures are low enough, say in the 10-11 torr range...?
Is its half life even long enough to detect....?
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Richard Hull
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Re: Lithium Detection

Post by Richard Hull »

Lithium 6 is stable and will never decay. To get enough Li6 to detect with an RGA even with an electron multiplier to extend the range to 10-13 torr, You would have to do one heck of a lot of fusion. The He3 + He4 fusion is not an easy amateur reaction either.

A lot of this has been hashed over about 4 years ago on the first list. There are a lot of fusion possibilities all but one or two are tough to do. I would think that if we can't do the easy ones well, the tougher ones ought not even be considered beyond simple amusement.

Each reaction has a minimal seed energy level. Only d-d and d-t are normally considered due to the relative ease of their fusion. Compared to all other reactions d-t can almost be casually fused in a TV picture tube environment!! Unfortunately, even this prime combo can't be efficiently fused....YET.

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
guest

Re: Lithium Detection

Post by guest »

To add to the fun, 3He is hideously expensive. I may be misquoting., but I think one of the earlier U of Wisconsin papers mentioned a price of around $5k/gm. Too steep for me...
DaveC
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Re: Lithium Detection

Post by DaveC »

I think... a good RGA or better yet, a real Mass Spectrometer, in fine tune, ( ionization energy set to just enough to make Li ions, electron multiplier detector in good condition, cranked way up, and a good electrometer) you can probably get below 10 -15 torr. Light molecules like lithium are a bit easier to detect too, since they travel faster for the same energy, which affects the efficiency in initial impact ionization electron production at the multiplier.

The analyzer volume is hard to get below a couple hundred mL, or about 0.01Mole. So 10-16 torr partial pressure of a Li Ion would be about 10-19 atm, or about about 100 molecules, give or take a bit. I suspect this ...should... be detectable, if the process runs without too large an increase in background pressure. But it would be a delicate measurement.

Anyone agree?

Dave Cooper
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