A difficult question that any explanation will need to address is that of the gamma ray signature of the LENR experiments. Almost any proton or neutron capture reaction is going to give off powerful gammas, but gammas are not seen in a significant quantity. The evidence here is not unequivocal -- Andrea Rossi is shielding his device with lead, for example, and it's possible that the signature will depend upon the makeup of the device and how it's operated.
But there have been different ways of getting at the problem of low gamma levels. One is to propose inverse Rydberg states, where only a little amount of energy is given off for each fractional transition. If I understand what Ed Storms is suggesting, he's thinking there might be a kind of slow compression of protons sandwiched between electrons, which emits x-rays in a very specific direction and hence are unlikely to be picked up. Other theories, if I've understood them, have suggested that the Mossbauer effect is able to convert the energy directly into phonons. A relevant question here is whether you can have a kind of downshifting from gammas to soft x-rays and extreme ultraviolet. Perhaps there's two challenges here, getting from gammas to hard x-rays, and then getting from hard x-rays to soft x-rays and EUV. The second challenge might be dealt with by a kind of resonance within a nanocavity in the crystal which causes the radiation to gradually convert from a shorter wavelength to a longer one. This could be unlikely, because nickel, to take an example, is almost transparent to high energy photons for most angles of incidence. But apparently under the right conditions, such as when the grazing incidence is very slight, a cavity can potentially confine x-rays. These slides provide an interesting discussion of the topic and mention a number of journal articles that might be of interest: http://www.aps.anl.gov/video/APS_Colloquium/2006/030106/030106.pdf An interesting point that was mentioned was that if you have a cavity that is filled with free atoms of another species, you can potentially get a highly directional coherent scattering, which presumably could keep the grazing incidence low. Eric
