Quoting from the Windom and Larsen (WL) article at:
http://arxiv.org/pdf/cond-mat/0509269v1
"Low energy nuclear reactions in the neighborhood of metallic hydride
surfaces may be induced by ultra-low momentum neutrons. Heavy
electrons are absorbed by protons or deuterons producing ultra low
momentum neutrons and neutrinos. The required electron mass
renormalization is provided by the interaction between surface
electron plasma oscillations and surface proton oscillations. The
resulting neutron catalyzed low energy nuclear reactions emit copious
prompt gamma radiation. The heavy electrons which induce the
initially produced neutrons also strongly absorb the prompt nuclear
gamma radiation, re-emitting soft photons. Nuclear hard photon
radiation away from the metallic hydride surfaces is thereby strongly
suppressed."
"... the mean free path of a hard prompt gamma ray is L ∼ 3.4 Å~
10−8 cm. Thus, prompt hard gamma photons get absorbed within less
than a nanometer from the place wherein they were first created."
" ... one finds a neutron mean free path of ∼ 10^−6 cm. An ultra
low momentum neutron is thus absorbed within about ten nanometers
from where it was first created. The likelihood that ultra low
momentum neutrons will escape capture and thermalize via phonon
interactions is very small."
Twice the Bohr radius of 0.53 Å is about 1x10^-10 m, an angstrom, or
a tenth of a nanometer. So, the neutron mean free path WL suggest,
10^−6 cm = 10^-8 m, is about 100 hydrogen atoms in width. Heavier
atoms are not much bigger than hydrogen because the atomic radius
does not grow much with atomic number, e.g. radii in angstroms: Pd
1.79, Au 1.79, Ni 1.62, Li 2.05, K 2.77, Al 1.82, Cu 1.57, Pb 1.81.
WL apparently ignore the fact that substantial fusion, especially
helium generation, in electrolysis experiments apparently happens
near but below the surface of the cathode. WL apparently ignore the
lack of neutron activation of lattice nuclei, the atomic radii of
which are not much larger than the Bohr radius, and make no effort to
account for lattice element transmutation without signatures. The WL
math and QM is possibly controversial (e.g. via Hagelstein and
Chaudhary), but the logic and common sense in problem definition and
conclusions are clearly controversial and not so complex issues.
Experimentally, and by their own results, their theory can be tested
by including in a co-deposition electrolyte extremely small trace
amounts of metals (cations) suitable for delayed gamma analysis. Even
that is not necessary in most LENR experiments, because the primary
cathode ingredients include NAA sensitive elements in large proportion.
It would be useful to hear the WL take on why the lack of neutron
activation LENR experiments, even those otherwise generating clear
nuclear signatures, doesn't deny the validity of the WL theory. If
their theory encompasses heavy element transmutation then the WL
neutrons have to penetrate heavy nuclei. The effects of adding
thermal neutrons to nuclei is well known. The decay of the resulting
compound nuclei is well established. Some of these decays have long
half-lives and energetic emissions. There is good reason to expect
slow nuclei penetrate heavy nuclei just fine given the extremely low
neutron velocities at which the Mossbauer effect has been measured.
The Mossbauer effect in some cases peaks right on the zero velocity
line. If a di-neutron or ultra-cold neutron can bounce off heavy
atoms then they can be, will be, quickly thermalized, and thus are no
longer ultra cold. The di-neutron is often described as not bound.
If a di-neutron is indeed very weakly bound it should quickly
separate into two neutrons. Neutron activation should be readily
detected, especially in the cases where the cathode was chemically
digested prior to counting.
Real progress is not made in proving a theory until extensive efforts
have been made to disprove it. A few experiments consistent with a
theory exist does not prove a theory. In the case of the WL theory
it seems to me the key experiments to do would be those which are
focused on and carefully look for neutron activation.
Neutrons in the lattice can not be an explanation for the number of
events required to produce even modest excess heat. Neutrons produce
neutron activation, i.e. make some nuclei radioactive with half-lives
that make them easily detectable post-experiment. If neutron
activation were occurring in lattice material elements then it would
have been discovered long ago, because neutron activation analysis
(NAA) is a commonly used and well developed technique. The gamma
spectra and delayed gamma production decay curves are well known and
used in delayed gamma NAA. This information is used to sense trace
amounts of elements.
Consider the sensitivity of NAA for various elements in picograms
(10^-12 g):
http://en.wikipedia.org/wiki/Neutron_activation_analysis
Consider further the fact that the NAA sensitive elements are not
only present in trace amounts in CF electrodes or electrolytes, they
are *primary ingredients* in some experiments, e.g. Ag, Cl, Cu, Na,
Ca, K, Pt, Ti, S. Also present in large quantities are sometimes:
W, Ta, Th, U, V, Mo, Pb. These things are readily detectable in
microgram order quantities. No matter how slow the neutrons, it is
not credible NA is not happening when fusion and heavy element
transmutation clearly is happening. The gammas should light up
geiger counters even long after electrolysis is over. Further, the
spectra and decay curves would be readily identifiable as to origin.
One of the mysteries of CF is why significant high energy radiation
doesn't happen as a general rule.
Note that this is not to say that NA could not happen in certain
environments, even from deflation fusion. It simply does not happen
to a sufficient degree in typical CF experiments, so is not an
explanation for the *primary* processes that produce the amounts of
excess heat or heavy LENR that has been observed.
I think the energy deficit which occurs in CF reactions, necessary to
depress some He* fission channels, and the dissipation of the
reaction enthalpy via multiple low energy gammas, can only occur via
a free electron in the nuclear mix *at the moment of fusion*. What I
have proposed is a means for that happening which might be confirmed
by looking for rare but detectable strange matter decays from CF
cells. This means not only explains the above effects, it explains
how the Coulomb barrier is overcome as well.
If ultra slow neutrons can not move far enough to effect NA (neutron
activation), thus generating both prompt and readily detectable
delayed gammas, then they can not effect heavy element transmutation
LENR with the closest atoms, the lattice heavy elements. Fusion with
a hydrogen atom that is typically even further away than the nearby
lattice heavy elements is then also precluded.
CF is known to happen below the surface, within the lattice. Whether
it also happens on the surface due to collective surface oscillations
as suggested by Windom and Larsen is immaterial. An explanation of CF
needs to cover all observations, not just a select few.
The distance between lattice sites, i.e. the distance from the
potential well an absorbed hydrogen nucleus occupies (a lattice site)
and the adjacent potential well another hydrogen atom can occupy, is
less than the distance between a lattice site and the adjacent
lattice atoms.
Windom and Larsen estimate slow neutrons to be absorbed in less than
a nanometer, 10^-9 meter, about 10 angstroms. That is about 10
hydrogen atoms, or 3 Pd atoms in width. If neutrons can make it 3.5
Å into a nearby hydrogen nucleus they can make it 1.79 Å into Pd or
another lattice element just as well. There are no other nuclei in
the way, so cross sections are not even an issue. Heavier atoms are
not all that much bigger than light ones because atomic radius does
not grow much with atomic number, e.g. radii in angstroms: Pd 1.79,
Au 1.79, Ni 1.62, Li 2.05, K 2.77, Al 1.82, Cu 1.57, Pb 1.81. If
fusion is occurring at a rate sufficient to account for excess heat
then NA should occur at a huge rate also, one that could not possibly
be missed.
Heavy LENR is known to occur, has been observed, and thus requires
just as much explanation as other CF results. The lack of high
energy radiation signatures for both CF and heavy transmutation LENR,
both of which are known to occur both very close to and below the
surface, requires an explanation. The unusual branching ratios
observed require an explanation. The presence of ultra-slow neutrons
in the lattice provides no explanation for these things.
Gammas from NA should be readily observed from heavy element
transmutation if it is due to neutrons. The presence of hypothesized
high mass electrons on a cathode surface, near surface hydrogen
fusion reactions, were suggested to absorb fusion gammas in less than
a nanometer. This explanation can not account for gamma absorption
near heavy elements. NA gammas should be readily detectable.
I think the presence of a free electron in the nucleus at the time of
fusion is the logical explanation of all these things, how the
Coulomb barrier is breached, why high energy particles and gammas are
not seen from hydrogen fusion reactions, why the branching ratios are
so skewed, and why almost no signature, including heat, is seen
corresponding to nuclear mass changes from heavy lattice element
transmutation. How this is proposed to happen is described in "Cold
Fusion Nuclear Reactions" at:
http://www.mtaonline.net/~hheffner/CFnuclearReactions.pdf
with ancillary material here:
http://www.mtaonline.net/~hheffner/dfRpt
Best regards,
Horace Heffner
http://www.mtaonline.net/~hheffner/