Merge branch 'main' of github.com:project-ida/notes

Author: mklilley

latex/Nucleonics.tex

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+\urlstyle{same}
+
+\title{Nucleonics}
+  \author{Matt Lilley}
+  \date{\today}  % Default to today if no date is provided
+
+\begin{document}
+\maketitle
+
+\section{What is nucleonics?}\label{what-is-nucleonics}
+
+\begin{quote}
+\textbf{Nucleonics is a scientific and engineering discipline that
+studies and applies the principles of physics to design, create, and
+operate devices that manipulate nucleons.}
+\end{quote}
+
+We take inspiration from the emergence of electronics that marked a
+fundamental shift in humanity's relationship to information. Underlying
+that shift was a revolution in the way we understood and interacted with
+electrons: rather than continuing to blow large aggregates of electrons
+through vacuum tubes, the transistor represented deliberate, precise
+control of electronic states.
+
+What if, similar to our control of electronic states, we gained precise
+control of nuclear states? Before we can answer that question, it's
+essential to first ask the ``Is it possible?'' question.
+
+Some of the essential physics of nucleonics (e.g.~nuclear superradiance)
+was already proposed in
+\href{https://doi.org/10.1103/physrevlett.14.589}{1965 by Terhune and
+Baldwin}, but it's only in recent years that it's been possible to
+verify those ideas - see
+\href{https://www.nature.com/articles/s41567-017-0001-z}{Chumakov et.al
+2017}. We're now seeing increased interest and experimental progress in
+the controlling of nuclear states
+e.g.~\href{https://www.science.org/doi/10.1126/sciadv.abc3991}{Bocklage
+et.al 2021} ,
+\href{https://www.nature.com/articles/s41586-021-03276-x}{Heeg et.al
+2021}, and
+\href{https://www.nature.com/articles/s41567-024-02773-w}{Chai et.al
+2025}.
+
+The answer seems to be yes - nucleonics is possible. Now to the question
+of ``What if?''.
+
+\section{A vision for nucleonics}\label{a-vision-for-nucleonics}
+
+What if, similar to our control of electronic states, we gained precise
+control of nuclear states? We might imagine a world where nuclear
+radiation is a thing of the past or a world where we can increase
+nuclear fusion rates in solid states to technologically relevant levels.
+
+There are other possible visions for nucleonics, e.g.~one might take an
+information technology angle relating to nuclear spintronics. However,
+our vision takes an energy angle. We can recast the vision into a
+``mission statement''
+
+\begin{quote}
+\textbf{We want to enable rational engineering of small-scale devices
+fueled by clean nuclear energy}
+\end{quote}
+
+Now that we have a ``destination'', how are we going to get there? Are
+there any potential roadblocks along the way? We need a roadmap.
+
+\section{Nucleonics Roadmap}\label{nucleonics-roadmap}
+
+To meet the vision, we need nucleonics to be more than possible, we need
+it to be practical and so the essential question that a nucleonics
+roadmap is answering is:
+
+\begin{quote}
+\textbf{Is nucleonics practical?}
+\end{quote}
+
+It may be that manipulating nuclear states for the purposes of energy
+technology is sufficiently difficult to make it more of an academic
+curiosity than an enabler of new technology.
+
+From the energy perspective that our mission statement focusses on,
+practicality means that we need to be able to:
+
+\begin{itemize}
+\tightlist
+\item
+  Accelerate nuclear transitions by many orders of magnitude
+\item
+  Transfer nuclear energy from one type of nucleus to another
+\item
+  Control nuclear transitions with low frequency stimulation
+\item
+  Extract nuclear energy in benign forms
+\end{itemize}
+
+From a theoretical perspective, nucleonics does seem practical. In 2024,
+\href{https://arxiv.org/pdf/2501.08338}{Hagelstein et.al} showed for the
+first time that known quantum physics principles could be applied to
+satisfy the above criteria and moreover explain long standing
+experimental nuclear anomalies found in LENR experiments.
+
+Hagelstein's theoretical framework relies on combining several pieces of
+well established quantum physics in a novel way. The central question is
+whether Mother Nature respects this novel combination. The framework
+needs to be stress tested in several carefully designed experiments in
+order to pass the ultimate litmus test.
+
+\subsection{Accelerating nuclear transitions by many orders of
+magnitude}\label{accelerating-nuclear-transitions-by-many-orders-of-magnitude}
+
+One of the key bit of physics responsible for accelerating nuclear
+transitions is Dicke Superradiance. First proposed by
+\href{https://doi.org/10.1103/PhysRev.93.99}{Dicke in the 1950s} for
+atoms and then extended by
+\href{https://doi.org/10.1103/physrevlett.14.589}{Terhune and Baldwin in
+the 1960s} for nuclei, Dicke's model showed that \(N\) particles can
+radiate/decay collectively up to \(N^2\) faster that an individual
+particle. In a solid lattice, the number density is
+\(\sim 10^{28} \ \rm m^{-3}\) and so Dicke enhancements can in principle
+be extremely large.
+
+The challenge for nuclear superradaince is how close the nuclei need to
+be for collective emission to occur. Dicke's model is based on all \(N\)
+nuclei being coupled together through an interaction with a common
+oscillating field. In order to get the full \(N^2\) enhancement, all the
+nuclei need to be located within a single wavelength of one other. The
+wavelength is determined by the frequency (and hence energy) of the
+field oscillations. Typically the frequency is chosen to be matched to
+the nuclear transitions which mostly have energies of
+\(E > 10 \ \rm keV\) and wavelengths of \(\lambda < 0.1 \ \rm nm\). In a
+typical solid lattice you can fit at most one particle in cube whose
+sides are given by such a small wavelength.
+\href{https://www.nature.com/articles/s41567-017-0001-z}{Chumakov et.al
+2017} achieved small levels of nuclear superradiance (\(\sim 10 \times\)
+rate enhancements) in \(\rm ^{57}Fe\) experiments because of this.
+
+Much larger Dicke enhancement rates are required for practical
+applications. Bridging the rate enhancement gap can in principle be
+achieved by choosing a low frequency (and hence long wavelength) that's
+mismatched with respect to the nuclear transitions. In such a set-up, a
+nucleus radiates a number of smaller energy oscillator quanta instead of
+a single large one. The challenge with this approach is that the more
+quanta that are involved, the slower the process becomes - this can
+dominate over Dicke enhancements depending on the specific details.
+
+There is a novelty in demonstrating Dicke enhancements with oscillator
+and nuclei that are mismatched. It would therefore be preferable to
+separate that novelty from the specific demonstration of extremely large
+nuclear Dicke enhancements. One way to do this is to repeat the Chumakov
+experiment but instead of using \(\rm ^{57}Fe\) we use
+\href{https://en.wikipedia.org/wiki/Isotopes_of_thorium\#Thorium-229m}{\(\rm ^{229m}Th\)}.
+
+\(\rm ^{229}Th\) has a nuclear isomer \(\rm ^{229m}Th\) whose existence
+was hypothesised for many years but
+\href{https://link.springer.com/article/10.1140/epjs/s11734-024-01098-2}{was
+only nailed down in 2024}. \(\rm ^{229m}Th\) is unique in that it has an
+extremely low energy nuclear transition energy of \(8.36 \ \rm eV\)
+which corresponds to a wavelength of \(148 \ \rm nm\). A cube of this
+size would contain about \(3\times 10^7\) nuclei at typical solid
+density - more than enough to observe some very large Dicke
+enhancements.
+
+The specifics of \(\rm ^{229m}Th\) require us to arrange the system to:
+
+\begin{itemize}
+\tightlist
+\item
+  Maximise radiative decay over internal conversion
+
+  \begin{itemize}
+  \tightlist
+  \item
+    Excite half of the \(\rm ^{229m}Th\) nuclei instead of all of them
+    will give us \(N^2\) enhancement of radiation and only \(N/2\)
+    enhancement of internal conversion
+  \end{itemize}
+\item
+  Minimise the reflection of the UV laser light from the surface
+
+  \begin{itemize}
+  \tightlist
+  \item
+    Embed the \(\rm ^{229m}Th\) into an UV transparent material
+  \end{itemize}
+\end{itemize}
+
+\printbibliography
+
+
+\end{document}