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Coupling between the lattice and internal nuclear degrees of freedom. Peter Hagelstein 1 and Irfan Chaudhary 2 1 Massachusetts Institute of Technology 2 University of Engineering and Technology, Lahore. The problem. Donor-receiver type model closely related to experiment

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coupling between the lattice and internal nuclear degrees of freedom

Coupling between the lattice and internal nuclear degrees of freedom

Peter Hagelstein1 and Irfan Chaudhary2

1Massachusetts Institute of Technology

2University of Engineering and Technology, Lahore

the problem
The problem
  • Donor-receiver type model closely related to experiment
  • Could account for excess heat in F&P experiment if we had a transition strongly coupled to the phonons
  • Could account for Karabut experiment if we had a transition strongly coupled to the phonons
  • Electron-nuclear coupling too weak
  • Electron-electron coupling in atoms too weak
  • Nuclear coupling strong enough…
  • But no known coupling with phonons
go back to beginning
Go back to beginning…
  • If nuclear coupling could exchange phonons, then we could understand new experiments
  • But we know that nuclear coupling does not exchange phonons
  • Let’s go back and see how it works…
  • If we understand why there is no coupling, perhaps we might be able to find some fine print
center of mass separation
Center of mass separation

Consider two-body problem with central field potential

Introduce center of mass and relative variables

clean separation
Clean separation

Hamiltonian in center of mass and relative coordinates separates

Center of mass

Relative

Center of mass and relative degrees of freedom are independent, with no coupling between them

clean separation is powerful and important
Clean separation is powerful and important
  • The separation between the center of mass problem and relative problem in nonrelativistic physics is very powerful!
  • Means that can work relative problem in rest frame
  • Means that can analyze center of mass dynamics independent of relative problem
  • Separation is clean even with many bodies
  • Our intuition about how the world works is strongly connected to this separation
separation of condensed matter and nuclear physics
Separation of condensed matter and nuclear physics

Suppose that we wanted to describe the coupling between condensed matter and nuclear degrees of freedom. We might start with a model that considers neutrons, protons, and electrons at the outset on equal footing:

separation of nuclear and condensed matter physics
Separation of nuclear and condensed matter physics

Since the center of mass problems and relative problems separate cleanly, the nuclear and condensed matter problems are independent in this model

Nuclear problem

Condensed matter problem

two separate fields
Two separate fields

Condensed matter physics

Nuclear physics

slide10

No basic coupling between condensed matter problem and internal nuclear problem in fundamental construction of the nonrelativistic theory. (But there is some weak coupling due to electron-nuclear interactions.) This basic result is a consequence of the clear separation of center of mass and relative problems in the nuclei.

take away message
Take away message
  • Donor-receiver model consistent with excess heat and Karabut
  • As long as can find a strongly-coupled transition
  • Electron-nuclear coupling too weak
  • Electron-electron coupling also too weak
  • Only coupling strong enough is internal nuclear
  • But internal nuclear separates cleanly
  • Which is why condensed matter and nuclear physics are separate fields
relativistic two body problem
Relativistic two-body problem

Two-body Dirac equation:

Normally people work with field theory models that are much more complicated… We choose Dirac model here since it is the simplest model that could conceivably be relevant.

center of mass separation is problematic
Center of mass separation is problematic
  • Problem is very old and very famous
  • Studied since 1930s
  • Mathematical problems associated with center of mass separation in relativistic problem
  • No general separation in literature
  • Mathematical no go theorem about separation
need for a cmns hamiltonian
Need for a CMNS Hamiltonian
  • Want to include configuration mass effects on lattice dynamics
  • Recently understood that we can work with Dirac models
  • We can make a new Hamiltonian to describe condensed matter nuclear physics (CMNS)
  • We hope that it clarifies what the strongly-coupled receiver transition is
need to revisit dirac
Need to revisit Dirac

Now assume that many states are present:

Can we get an equation for the expansion coefficients?

slide19

Each state now has its own kinematic mass, and we now understand the energy-momentum relation for each basis state.

off diagonal matrix elements
Off-diagonal matrix elements

New term

Mixing within relative part of problem

P. L. Hagelstein and I. U. Chaudhary, “Including nuclear degrees of freedom in a lattice Hamiltonian,” J. Cond. Mat. Nucl. Sci. (in press)

nonrelativistic limit
Nonrelativistic limit

Nonrelativistic limit of finite basis expansion:

slide23

Now have a better description for the dynamics of a composite particle (such as a nucleus. And we have a coupling between the center of mass motion and the internal nuclear states.

new relativistic model for nucleons and electrons
New relativistic model for nucleons and electrons

Start with relativistic model for nucleons and electrons

slide27

This gives us a new starting point for condensed matter nuclear physics modeling that includes coupling between vibrations and nuclear excitation

not two separate fields
Not two separate fields

Condensed matter physics

Nuclear physics

lattice nuclear hamiltonian
Lattice-nuclear Hamiltonian

Now use Born-Oppenheimer approximation to replace electrons with equivalent potentials between nuclei

slide30

Now we have a fundamental Hamiltonian for Fleischmann-Pons excess heat effect and Karabut collimated x-ray emission

slide31

If new coupling term goes away…

Then we recover usual condensed matter lattice model

take away message1
Take away message
  • Wanted a model to describe mass shift for excited nuclear configurations
  • Start with many-body Dirac model
  • Develop finite basis approximation
  • Get new relativistic and nonrelativistic finite basis models
  • Use to construct new condensed matter nuclear Hamiltonian
  • Get mass shift effect
  • Also get new coupling term
new matrix element
New matrix element

The new coupling matrix element in the case of the deuteron can be written as

results from numerical calculations
Results from numerical calculations

We used the Hamada-Johnston model for strong force interactions, and computed deuteron wavefunctions to evaluate the matrix element:

what does it mean
What does it mean?
  • We had estimated earlier that a coupling matrix element of 1 keV would allow us to be consistent with the model numbers of the Letts 2 laser experiment excess heat
  • The new evaluation of the coupling matrix element corresponds to a maximum of about 100 eV
  • Result is orders of magnitude larger than for electron-nuclear or electron-electron coupling
  • Is sufficiently large to motivate developing a new model for excess heat in Letts experiment and others
d 2 4 he calculation in progress
D2/4He calculation in progress

We are evaluating the new interaction matrix element now for phonon exchange in connection with the D2/4He transition

Calculation involves lots of terms and some significant numerical integrations. Hope to complete it in a few weeks

significance of results
Significance of results
  • Donor-receiver model requires estimates for coupling matrix elements
  • New relativistic CMNS Hamiltonian describes coupling between lattice and internal nuclear degrees of freedom
  • Now have receiver coupling matrix element for deuteron
  • Will shortly have donor coupling matrix element
  • Will allow ab initio calculation of excess heat within donor-receiver model