The Mossbauer effect has been mentioned in many past LERN experiments where gain is seen -- but in a nebulous way. In fact nickel as well as iron has a Mossbauer isotope (61 Ni)
Despite the association of heat with gamma radiation of any kind, when a thermal anomaly is seen with iron it is often cooling (magnetocaloric effect) rather than excess heating. The idea of a nucleus being “recoil free” essentially means it does not heat up so as to thermalize applied gamma radiation. In fact, cooling could be more likely than heating due to an as yet undescribed mechanism. Magnetic cooling in iron, due to a lossless resonance at 14.4 keV is a concept which fits into surprising phenomena known as the “Manelas effect”. For a nucleus to emit a gamma-ray and a second nucleus to absorb it with no thermal gain and then reemit it - implies a thermal loss since there is a time constant in which nothing else can take place (during that delay). The delay in iron is very long on that scale <50 ns. With nickel the and the Mossbauer gamma, the delay is much shorter and the radiation is much stronger likely (67.4 keV), so a magnetocaloric effect is far less by two orders of magnitude. That may be a naïve way to describe the situation but it could be one reason LENR with nickel is difficult to accomplish on a reliable basis and does not happen with iron at all .... since it could be the case that sometimes Nickel can self-cool with the magnetocaloric effect which cancels out thermal gain from the gamma. Iron is more likely to self-cool all the time unless the geometry forces the gamma to be retained longer. Thus an iron rod could heat but an iron sheet would cool due to gammas being emitted readily from the higher surface area and field lines. In all cases, the thermal anomaly would begin with a gamma, which could be initiated by some other mechanism such as neutron hopping - and since tunneling is involved, far less net energy is involved than the isotopic mass difference would suggest. Jones Yes it is clear that Meyer got the theory wrong - and possibly most of the data. Other features of the experiment are interesting in a historical context. I can find no claimed replication online. The significance of his experiment today is mostly in relationship to the more recent work of Hagelstein and Wallace. The possibility that iron could be unstable in any nuclear sense (i.e. “hopping”) raises the possibility of a “back door” to gain with both iron and nickel, which is so contrary to expectation that it doesn’t settle well with what we know or think we know about the nucleus. >Going back to the general principle of stimulating the element iron with waves >of another type and/or frequency, in order to cause actual isotope >transmutation - there is another entry: the Meyer-Mace device which received a >flurry of attention 20 years ago, was patented and then all but disappeared.. > >http://jnaudin.online.fr/html/mmcgen.htm Fe56 can't be converted to Fe54 unless you can find another isotope that is even hungrier for neutrons than Fe56. (Difficult considering that Fe56 is near the top of the binding energy curve). So I think their theory is probably nonsense, but they may have had something practical nevertheless.