I don't think BEC were using deuterium routinely, so how could the energy be coming from photo disintegration of deuterium?
The reaction can make deuterium from hydrogen. There is a small indication of that in the first example in the reference in my profile. In a second example in the reference in my profile, water (not deuterium oxide) is used as the source of hydrogen. Yet, the mass balance shows the production of de novo nitrogen. I suspect this is an example of entropy. That is a very slow reaction (deuterium production or neutron equivalent production) being coupled to a fast one (de novo nitrogen production).
There is never only low energy photons involved because of phats. The n squared relationship of phats will make some high energy photons of any electrolysis. Phats become a catalyst for fusion. Who needs muons when we got phats?
W may be right about no neutron but rather a neutron equivalent.