And I'm asking if you have seen any actual evidence that it happens. I have not, and the information I have seen, which I mentioned, leads me to believe that it should not have happened in any fusion experiments we've done to date. That's why I asked you for a reference.
> the sun is 1/10th of ITER's goal temperature so your well in the range for PP fusion
No, the ITER is not "in the range for PP fusion", because temperature is not the only requirement. You also need sufficient density. The density in the Sun's core is many orders of magnitude larger than the density of plasma in ITER or any other Earthbound fusion experiment. That has a huge effect on the PP reaction cross section.
As to PP fusion from what read. Without a large enough plasma the beta more common proton emission path >99.99% ends up costing more energy than you gain from beta-plus decay <0.01%. "The least stable is 5He, with a half-life of 7.6×10−22 seconds, although it is possible that 2He has an even shorter half-life" http://en.wikipedia.org/wiki/Isotopes_of_helium#Helium-2_.28...
How much less common? Again, have you seen any actual evidence that P-P fusion events actually happen in actual Earth-bound plasmas? Because the numbers I've seen indicate that at Earth-bound plasma densities, such events are so unlikely that we should not expect to have observed any.
PS: And thanks for this, it's good to be called out on something like this. I tossed out the PP comment without thinking though simple contamination is a far larger source of high energy neutrons.
It looks to me like the comment about the rate being too small to measure in the lab applies to the PP fusion into deuterium; that's the reaction referred to in the statement you quote. The positron that's produced is not a "beta-plus decay of deuterium"; it's a product of the PP fusion into deuterium, part of the same overall reaction.
As to PP fusion from what read. Without a large enough plasma the beta more common proton emission path >99.99% ends up costing more energy than you gain from beta-plus decay <0.01%. "The least stable is 5He, with a half-life of 7.6×10−22 seconds, although it is possible that 2He has an even shorter half-life" http://en.wikipedia.org/wiki/Isotopes_of_helium#Helium-2_.28...
As to the long term potential I don't think we can rule it out in the longer term, just that when people talk about fusion without neutrons they mean low levels or don't actually know what there talking about.