Transcript Thinking about cold fusion experiments

Energy from Fleischmann-Pons
experiments: How does it work?
Peter L. Hagelstein
Research Laboratory of Electronics
Massachusetts Institute of Technology
Outline
•Relevant experimental results
•Constraint on energetic particle emission
•Fractionation of a large quantum
•Coherent energy exchange
•Two-laser experiment
•Karabut experiment
•Proposed mechanism
•Conclusions
Electrochemical cell
Excess energy in F&P expt
4 MJ observed during 80
hours
Get 1.2 kJ for detonation of
equivalent cathode volume
(0.157 cc) of TNT
Effect not chemistry!
M Fleischmann et al, J Electroanalytical Chem 287 293 (1990)
But why no support for the
technology?
•Experiments point to new disruptive technology
•No place in nuclear physics, condensed matter physics for excess heat
effect in Fleischmann-Pons experiment
•If known physics rules out effect, easy to argue that experimental error
involved
•No support available for research and development on new technology
deemed inconsistent with known physics
•Clarification of mechanism could help move things forward
Constraints on energetic 4He
Observations of 4He correlated with excess energy are consistent with
a Q value (energy/He atom ratio) near 24 MeV
Important since mass difference between two deuterons and 4He is 24
MeV
2M[d]c2 – M[4He]c2 = 23.85 MeV
If we suppose a reaction of the form
d d  X 
4
He  X  23.85 MeV
Then we could gain information about what X is by measuring the
kinetic energy of the 4He
How to measure a energy?
•4He doesn’t go very far, and loses energy in PdD, D2O
•Hard to detect directly
•Propose indirect detection! When 4He hits deuterons can get
primary and secondary neutrons
•And neutrons can be measured outside of the cell
•But wait, neutron measurements have been done on cells
producing excess power!
Yield/energy for secondary neutrons
Klein (1990)
Y/E (n/J)
1
0.1
Ue = 800 eV
Gozzi (1994)
Ue = 0Wolf
eV (1990)
Takahashi (1993)
Scott (1990)
0.01
0.001
4
5
6
7
8
9 10
E (keV)
P. L. Hagelstein, Naturwissenschaften (2010)
20
30
What can we conclude?
•4He is born with a very low energy (less than 20 keV out of 24 MeV);
result similar for upper energy of t in tritium production (less than 12 keV)
•Can rule out all Rutherford picture reactions with two-body final states
(lowest 4He energy is about 76 keV for recoil with gamma or electron)
•If we add the practical constraint that energetic electrons and gammas
would have been detected if created in amounts commensurate with the
energy produced, then the constraint is much more severe
•If 24 MeV shared with deuterons, then sharing must involve more than
24,000 deuterons to be consistent with upper limit near 0.01 neutron/J
•Can rule out all Rutherford-picture mechanisms as inconsistent with
experiment
Impact on theory
•This result has a dramatic impact on theory!
•Can rule out nearly all proposals, as only a few can be consistent with
these constraints
•Only three approaches left:
1) Transfer reaction energy to condensed matter mode
2) Find new mechanism to slow down energetic MeV particles without
observable products
3) Find new mechanism for collective reaction that shares energy with
more than 24,000 nearby deuterons
The theoretical problem
•Nuclear system involves large (MeV) energy quanta
•Condensed matter system involves small (meV) energy quanta
•Not easy to exchange energy coherently between systems with
mismatched energy quanta
•But experiments seem to indicate that it happens
New model for fractionation of
a large quantum
Lossy spin-boson model:
Macroscopic
excited mode
E
0
Two-level systems
Loss near E
E  0
Letts 2-laser experiment
D. Letts, D. Cravens, and P.L. Hagelstein, LENR Sourcebook Volume 2, ACS: Washington
DC. p. 81-93 (2009).
Excess power with 2 lasers
lasers on
Pxs (mW)
300
200
100
0
0
200
400
600
800
t (min)
In single laser experiments, excess heat turns off when laser turns off; in twolaser experiments, excess heat stays on
What oscillator modes?
300
Pxs (mW)
250
200
150
100
50
0
0
5
10
15
20
25
30
f (THz)
Results from dual laser experiments of Letts, J Cond. Mat. Nucl. Sci. 3 59,77 (2010)
Dispersion curve for PdD
PdD
16
[110]
[111]
14
12
f (THz)
Operation was predicted
on compressional modes
with zero group velocity
[100]
10
8
6
4
2
0
XK
L
Coherent energy exchange
between phonons and nuclei
•Can we study effect in isolation?
•Excite compressional vibrational mode strongly
•Coherent energy exchange between mode and nuclei
•Would be easiest for lowest energy nuclear excitation
•If interaction with mode uniform in space, then nuclei excited in phase,
would expect collimated x-ray emission (linear phased array effect)
•So, which nuclei are best candidates?
What are lowest energy
nuclear transitions?
1.5 keV collimated x-rays in
Karabut experiment (ICCF10,11)
Pinhole camera
x-ray image of
cathode
Interpretation and model
•Propose interpretation of Karabut experiment:
•Discharge turn off causes excitation of compressional vibrational mode
•Highly-excited mode couples to strongly-coupled nuclear transition
•Allows weakly-coupled transition in
201Hg
to be excited
•In-phase excitation leads to phased-array effect collimation
•Consistent with Karabut experiment if 201Hg taken to be weakly coupled to
oscillator, and second transition strongly coupled
•Can only get consistency for phonon exchange in association with nuclear
configuration mixing
Proposed mechanism for
excess heat production
•Need to arrange for highly excited vibrational mode
•Need to arrange for vacancies in Pd (or Ni, or other metals)
•Need to load to create molecular D2 (or HD) near vacancies
•Highly excited phonon mode plus interstitial D causes mixing of
vibrational and nuclear (3S and 1D states) degrees of freedom
•If insufficient D, then highly excited phonon mode causes mixing of
vibrational and nuclear (host Pd, Ni, etc) degrees of freedom
•D2 interacts to make 4He (or HD to make 3He), with energy to
vibrational mode
•Need to remove helium (high temperature helps diffusion)
“Clean” vs “dirty” operation
•Operation with interstitial D and optical phonon mode excitation in the
model results in little excitation of host nuclei, get 4He and little else
•Acoustic mode operation in the model results in mixing with host lattice
nuclei to allow D2/4He and HD/3He transitions, but now can excite longlived states that decay by disintegration
•So PdD (and other metal deuterides) can run “cleanly” based on optical
phonon excitation in the model
•And NiH (and other metal hydrides) expected to run “dirty” based on
acoustic phonon excitation in the model
•PdD (and other metal deuterides) can run “dirty” if acoustic phonon
mode excitation used, but can get energy boost from induced fissions
Take away message I
•Large amounts of energy production observed in Fleischmann-Pons
experiments
•Absence of commensurate energetic nuclear radiation indicates that
fundamentally new physical process involved
•Only viable theoretical approach is for coherent energy exchange with
quantum fractionation
•Karabut experiment seems to show effect in isolation
•Letts 2-laser experiment seems to show effect for excess heat
production
Take away message II
•Theoretical models constructed which predict/explain coherent energy
exchange with fractionation of large quantum
•Models require highly excited vibrational mode
•In Fleischmann-Pons experiment, molecular D2 transitions to 4He,
energy goes into optical phonon models according to model
•In Piantelli experiment, molecular HD transitions to 3He, energy goes
into acoustic phonon modes according to model
•Acoustic mode operation according to model leads to inadvertent
excitation of long-lived fission unstable states of host nuclei, causing
substantial induced disintegration (with energy loss in NiH, and energy
gain in PdD)