Hi, I typed up some notes that come from an email exchange between Robin and myself. They are about the possibility of the forced "decay" of isotopes that do not normally undergo alpha decay (emission of a helium-4 nucleus).
Eric This briefly describes a possible alpha decay channel in otherwise stable elements. It is inspired by a recent paper by Urutskoev and Filippov [1], although, inconsistent with their pessimism that “transformations” are unlikely to produce much in the way of energy, the pathway proposed here might produce useful energy if it can be made to happen at scale. Certain isotopes are unstable under alpha decay, for which, over a period of time, an alpha particle will be emitted. Once the alpha particle has departed, the resulting daughter nucleus will have four less nucleons. For example: 187Re => 4He + 183Ta + 2 MeV (half-life ~ 41e9 years) Here a rhenium-187 nucleus has been observed to alpha decay to tantalum-183 with a half-life of about 41 billion years. There are other isotopes that are observed to be stable, but which, if an alpha particle could somehow be separated out, the reaction would be an exothermic one: 192Pt => 4He + 188Os + 2422 keV (no observed half-life) In this case, if a platinum-192 nucleus could be made to part with an alpha particle, the decay would be to osmium-188 and would produce 2.4 MeV of energy. Because there has been no observed half-life, platinum-192 is said to be “observationally stable.” The line between isotopes that are stable and unstable under alpha decay is not a clear one. There is a known relationship between the energy of the separation and the half-life. All else being equal, the higher the energy of the separation of the alpha particle the shorter the half-life. Typical half-lives of heavy even-even nuclei range from ~ 0.1 second, at ~ 10 MeV (thorium-218), to 1e18 seconds, at ~ 4 MeV (thorium-232) [2]. The relationship is roughly logarithmic, so that if you go below 4 MeV, the half-lives get longer and longer. Presumably some isotopes are still unstable against alpha decay and we simply haven’t developed the methods to measure the decay rates because they are of such long duration. One question is whether isotopes in which there is no observed half-life actually are unstable under alpha decay, and the half-life is simply too long for us to measure it. If so, perhaps these long-lived isotopes are actually only “quasi-stable,” we can do something to the system to speed up their decay. Assume for the moment that electrons can do the trick. Here are some possible reactions that would result under a PdD electrolytic system with typical impurities in the palladium: e- + 190Pt => e- + 4He + 186Os + 3252 keV e- + 192Pt => e- + 4He + 188Os + 2422 keV e- + 191Ir => e- + 4He + 187Re + 2083 keV e- + 204Pb => e- + 4He + 200Hg + 1969 keV e- + 194Pt => e- + 4He + 190Os + 1522 keV e- + 195Pt => e- + 4He + 191Os + 1176 keV e- + 206Pb => e- + 4He + 202Hg + 1135 keV e- + 193Ir => e- + 4He + 189Re + 1018 keV e- + 197Au => e- + 4He + 193Ir + 972 keV e- + 196Pt => e- + 4He + 192Os + 812 keV e- + 208Pb => e- + 4He + 204Hg + 517 keV e- + 207Pb => e- + 4He + 203Hg + 392 keV e- + 198Pt => e- + 4He + 194Os + 107 keV As can be seen, all of these reactions are energetically possible. If the electron can somehow be made to decrease the half-life of what we’re calling “quasi-stable” isotopes, then the ones with more energetic alpha separation energies might start to decay at a rate that would be observable and possibly even sufficient for generating energy. Since the above reactions are for impurities in palladium, they might be a source of the helium that has been seen in PdD LENR experiments. What might cause electrons to decrease the half-life of quasi-stable isotopes, so that they decay at an appreciable rate? Alpha decay is a quantum mechanical tunneling process in which an alpha particle tunnels through the width of the Coulomb barrier rather than crossing over the top. A change in the charge density around the volume of the nucleus (e.g., under the agency a discharging arc of electrons passing through the volume) might modify the Coulomb barrier and possibly decrease its width. With the decreased barrier width, decays that would have taken too long to measure might now proceed with an appreciable half-life during the time that the arc is underway. If electron-mediated decays of this kind were responsible for the helium measured in PdD electrolysis experiments, they might explain the correlation between helium and heat that has been seen. In addition, since the separation energies are relatively small, they will be on the order of ~ 1 MeV per alpha particle nucleon or less and will result in relatively little penetrating radiation. But there would also be many difficulties that would need to be explained. First, there is nothing obvious about why there might be a hydrogen isotope effect, which has been seen in many PdD LENR experiments; and indeed there is no obvious role to be played either by hydrogen or deuterium. (Note that this is different than saying that there is no isotope effect or that deuterium plays no role.) Second, a more in-depth investigation shows that decays of this kind are unable to explain many of the transmutations that have been reported. Third, neither lithium nor nickel are expected to participate in this process. So if excess heat is really happening in the nickel system, it would need to be explained by something else. For these reasons, If the alpha decay process described here is eventually found to occur, there are many questions that come up. It also raises the possibility that there several unknown nuclear processes involved in LENR rather than a single one, each of which have escaped scrutiny up to now. This takes us in a direction opposite of the “conservation of miracles.” The general idea described here was anticipated by William Barker in a 1991 patent. Barker was focusing on remediating radioactive waste, while the focus here has been on initiating alpha decay in otherwise stable nuclei. [1] Leonid Urutskoev, D. V. Filippov, "Phenomenological model of collective Low Energy Nuclear Reactions (Transformation).” http://egooutpeters.blogspot.ro/2015/10/leonid-urutskoev-phenomenological-model.html [2] Krane, Kenneth, "Introductory Nuclear Physics," 1988 (John Wiley & Sons), p. 249. [3] William A. Barker, “Method for enhancing alpha decay in radioactive materials” (patent). http://www.google.com/patents/US5076971
