Constraints on energetic particles in the Fleischmann–Pons experiment
In recent Fleischmann–Pons experiments carried out by different groups, a thermal signal is seen indicative of excess energy production of a magnitude much greater than can be accounted for by chemistry. Correlated with the excess heat appears to be 4He, with the associated energy near 24 MeV per helium atom. In nuclear reactions, the energy produced is expressed through the kinetic energy of the products; hence, it would be natural to assume that some of the reaction energy ends up as kinetic energy of the 4He nucleus. Depending on the energy that the helium nucleus is born with, it will result in radiation (such as neutrons or x-rays) that can be seen outside of the cell. We have computed estimates of the expected neutron and x-ray emission as a function of helium energy and compared the results with upper limits taken from experiments. Experimental results with upper limits of neutron emission between 0.008 and 0.8 n/J are found to correspond to upper limits in alpha energy between 6.2 and 20.2 keV.