There does exist a provocative implication to the expected (but missing) high branching ratio of 50%, which they mention here. IOW the issue is why is so little 3He seen in LENR as well as so few neutrons -IF- this reaction is favored half the time:
d + d -> 3He + n (Q = 3.3MeV) Especially when combined with an observed neutron emission rate which is -10e7 times smaller than expected from the reported levels of energy generation. OK, if the neutrons were ultracold due to the circumstance, and in effect stayed localized, then they might conceivably react again in a 3He(n,γ)4He reaction - BUT instead of the γ (gamma) being radiated, in the constrained matrix of LENR we have an immediate internalized photodisintegration of 4He. This makes things reversible but with a significant "free energy" gap, presumably to be made up by ZPE ;-) Ha ... ROTFL However, some 4He would not photodisintegrate, so there should still be a few big gammas, which are not seen - just as with the other scenarios, and consequently this is unlikely but slightly less unlikely than D + D -> 4He (if we stick to standard reaction branching ratios of hot fusion). Anyway - worth a mention on Vo, but no place else ... especially since there is some available data (not from LENR but from hot fusion) for the 3He(n,γ)4He reaction http://prola.aps.org/abstract/PRC/v48/i5/p2375_1 Jones
