STM-D-0782Paper2022Published and peer-reviewed

Recent Progress on Phonon-Nuclear Theoretical Models

Peter L. Hagelstein

Abstract and summary · read the original at the source

In one page

Peter Hagelstein, at MIT, has spent three decades on one question about the Fleischmann–Pons experiment: if the heat is nuclear, where are the fast particles? Textbook nuclear reactions throw their energy out as flying fragments, and those are not seen in amounts that match the heat measured. His answer is that the energy leaves as lattice vibration instead of as debris, and this review is the working state of the model built to make that happen. The chain has three links. A 24 MeV quantum, from a deuterium pair becoming helium, is handed to a nucleus in the metal. That excitation is then subdivided across more and more nuclei at lower and lower energy. What is left is down-converted into an enormous number of vibrational quanta. The coupling that allows any of it is a relativistic phonon–nuclear interaction Hagelstein derives from a many-nucleon Dirac treatment, and the prize he points to is a change in the rate law itself, from the square of the tunnelling factor to the tunnelling factor alone.

Why it matters hereChapter 12 is about making nuclei react inside a lattice rather than inside a plasma, and this is the most developed account of how the released energy could arrive as heat with no commensurate flying particles. Its rate argument is the one to carry away: coherence changes the exponent on the tunnelling factor, and that exponent is the whole difference between a rate nobody could measure and a rate that runs a device.

What it claims

01The theoretical starting point is the absence of commensurate energetic nuclear particles, which implies that nature has found a way to take a very large 24 MeV nuclear quantum and split it into an enormous number of lower energy quanta — on the order of a billion of them — a down-conversion with no precedent in the literature.Section 1, Introduction
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02Coherence changes the rate law. An incoherent fusion rate is governed by the Golden Rule and is quadratic in the coupling matrix element, so it carries the Gamow tunnelling factor squared; a coherent quantum process can be linear in that matrix element and therefore linear in the Gamow factor alone. Since the Gamow factor here is of order ten to the minus fortieth power, the difference is a dramatic acceleration of the reaction rate.Section 1, Introduction, the paragraph accompanying Figure 1
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03The coupling proposed is relativistic rather than electromagnetic: a nucleus embedded in a lattice must be consistent with relativity, undergoing Lorentz contraction and spin and isospin rearrangement as it moves, so changes in the internal nuclear state as the nucleus moves with the lattice vibrations imply a low-order phonon-nuclear interaction stronger than the weak second-order interaction available through local electric and magnetic fields — and it answers how fermi-scale internal nuclear degrees of freedom can talk to vibrations organised across a great many atoms.Section 1, Introduction; Section 2, lowest-order phonon-nuclear interaction from the Dirac model; Section 6, covariant model
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04The excess heat model runs in three stages: excitation transfer of the 24 MeV quantum from the deuterium-to-helium transition into a palladium or other lattice nucleus; a subdivision step giving two excited nuclei at roughly 12 MeV each, and further steps reaching thousands of nuclei at much lower excitation, likely impurity nuclei since the palladium isotopes have no long-lived low-lying excited states; and finally down-conversion of that lower nuclear excitation into phonons.Section 1, Figure 1; Section 13, Subdivision; Section 16, Figure 18
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05There is hardware behind the theory. Hagelstein’s laboratory reports evidence for resonant phonon-mediated nuclear excitation in observations of dynamic angular anisotropy, and observations consistent with non-resonant excitation transfer in delocalization experiments, using cobalt-57 decaying into excited iron-57 under stress-induced terahertz vibration; because the location, frequency and strength of those vibrations are not known well enough to model, a simpler resonant excitation transfer experiment in a near single crystal sample is set out, choosing a nucleus with an electric dipole transition so that only one phonon need be exchanged per nuclear transition.Section 1, Introduction; Section 14, Phase coherence with resonant excitation transfer, and Sections 14.1 and 14.2
On the bench now
06A caesium-137 excited state at 5494.2 keV is identified as nearly resonant with the hydrogen-deuterium to helium-3 transition at 5493.478 keV, which suggests a route by which repeated excitation transfer could populate highly excited caesium-137 states that beta decay faster than the ground state — a possible mechanism behind the accelerated decay rates reported by Kornilova, Vysotskii and coworkers, and a test that would be run by measuring the 661 keV emission before and after.Sections 10.2 and 11, with Figures 8 and 9; Section 11.4, caesium-137 as an indicator of anomalous energy exchange
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Read it · abstract

Abstract

Excess heat in the Fleischmann-Pons experiment presents numerous challenges for theorists, the biggest of which is to account for the absence of energetic nuclear particles in amounts commensurate with the energy produced. Our focus has been on the development of such a model, with recent progress reviewed. To account for excess heat production we contemplate a complicated model based on nuclear excitation transfer, subdivision and the down-conversion of keV nuclear quanta to a large number of phonons. The phonon-nuclear interaction that provides the foundation has been derived from a many-nucleon Dirac formalism, and we discuss recent efforts to confirm and improve upon the derivation. The quantification of the models under consideration require the evaluation of phonon-nuclear matrix elements, with recent progress discussed. The first step in the excess heat model involves the excitation transfer of a 24 MeV quantum associated with the D2/4He transition, which motivates a consideration of modeling and connections with experiments showing low-level energetic nuclear emissions. The analogous first step in the case of the 5.5 MeV quantum associated with the HD/3He transition is considered, where there is the possibility of low-level energetic nuclear emission, and where the issue of the availability of near-resonant energy levels can be studied. A nearby level in 137Cs is identified, which suggests a possible mechanism for the acceleration of the decay rate. We have recently revisited the issue of the null reaction, in which a D2/4He transition leads to the production of a compact D2 state from 4He, with the conclusion that this may be important in models for excess heat production and for low-level nuclear emission. Progress on subdivision is reviewed, including connections with experiments showing low-level nuclear emission, and candidates for laboratory tests. The possibility of a new 57Co/57Fe resonant excitation transfer experiment in a near single crystal sample is presented. A numerical approach for the evaluation of the rate for excess heat production in the models under discussion is discussed.

Peter L. Hagelstein, Massachusetts Institute of Technology. Journal of Condensed Matter Nuclear Science 36 (2022) 210–246.

(Abstract only. The complete review is free to read at https://jcmns.org/article/72598.pdf and via https://doi.org/10.70923/001c.72598 — see the rights note for why the full text is not reproduced here.)

The way in

https://doi.org/10.70923/001c.72598Licence checked directly. The article page and the PDF at jcmns.org carry the line ‘© 2022 ICCF. All rights reserved. ISSN 2227-3123’ and no Creative Commons statement, so only the abstract is reproduced here. The complete article is free to read at the journal. The summary, the claims and the locators below were written from the full published text, J. Condensed Matter Nucl. Sci. 36 (2022) 210–246, Research Laboratory of Electronics, Massachusetts Institute of Technology.

How to cite it

Peter L. Hagelstein (2022) Recent Progress on Phonon-Nuclear Theoretical Models. doi:10.70923/001c.72598

Where it sits in the curriculum

Lattice confinement fusion