In reply to Eric Walker's message of Fri, 1 Mar 2013 22:47:07 -0800: Hi, [snip] >"the penetration depth of 20KeV deuterons in a metal is not 30 atoms, it's >measured, and it's like microns or a mm (I didn't look it up, but it's the >same as alpha particle penetration in order of magnitude), it's just not 30 >atoms. The ionization is not as efficient as he imagines. I am tired of >repeating this, it is well known experimental fact, no matter how >counterintuitive it is that you can have charged particles zipping through >matter. This was the original stopping power mystery that motivated Bohr >and Bethe.
The stopping power of a material to 20 keV deuterons should be about the same as for 10 keV protons. There is a handy online calculator available for the latter at http://www.physics.nist.gov/PhysRefData/Star/Text/PSTAR.html. Since Pd is not on their list of materials, I chose Silver which is next to it in the Periodic Chart, and hence has almost the same electron density as Pd. This results in a CSDA range of 0.182 microns, or about 630 atoms. > >"Regarding the "entering the Pd nucleus to fuse" OF COURSE NOT, the >deuterons do not enter the Pd nucleus, I never suggested they did. >they have nowhere near enough >energy. They fuse about 100 Fermis away from the Pd nucleus, a K-shell >radius away, and then they transfer the energy by virtual photon >(electrostatic interaction) to the Pd nucleus. This happens at a distance, >it doesn't require contact. Electrostatics is nonlocal. The matrix elements >are not small, because the charge on the Pd nucleus is 46, that's a lot of >charge. I agree. > >"The details of banding of deuterons, if it happens at all, are difficult >to work out, I don't know if they behave more like particles or like waves, >and it doesn't really make much difference. That's simply a question of >their coherence time, the time to do something to a phonon or an electron. >In any case, the deuterons bump around the atoms, focusing near the nuclei, Where does "focusing near the nuclei" come from? Given the positive charge of deuterons, I would expect them to avoid Pd nuclei like the plague. As they penetrate deeper into the electron shells of Pd atoms, the charge on the nucleus becomes ever more exposed (less electron shielding), resulting in an ever increasing repulsive force. This tends to keep them away from precisely the place where he would have them gather. (Note BTW that this is exactly the reverse of the situation where deuterino-deuteride - a negative ion, is involved. These *would* behave just as Ron wishes!) >and the first place where you would see fusion is near a nucleus, at a >range where you could potentially transfer energy to the nucleus. Here we agree. I don't disagree with Ron's overall concept, it's just that I think that he overestimates the chances of success. >This >doesn't require massive conspiracy, or some weird violation of physical >law. All you need is a concentration of deuterons high enough to lead to >fusion, as this fusion will naturally happen unnaturally close to a Pd >nucleus, simply from the mechanism of acceleration of the deuterons, >through the K-shell holes. I can understand an Auger like process, where the D+ accepts the energy and is accelerated, but I suspect the direction of acceleration would be more or less random, resulting in the D ion shooting off through the lattice, from where we come back to the "focusing near the nuclei" question here above. >It's not a crazy idea, it's just something that >needs to be tested in detail, through experiment. Agreed. > >"The easiest experiment is simply to shine X-rays on a deuterated metal, >and see the broadening of the K-shell line into a band (if it happens). If I understand the implication here correctly, then this will only test part of the theory, to wit that D's accept the Auger energy rather than electrons. It won't test whether or not this actually results in a significant number of fusion reactions. >This is an indication that the K-shell and the deuteron states are mixed >up. You can also see this from enhancements of beam fusion on deuterated >targets, and this has been observed in Russia, in the beam experiments, and >the enhancement for the process is by a small factor, but the detection is >through detecting neutrons, so it is blind to any three-body reaction that >might be taking place. The question is, was excess heat detected concurrently? Perhaps the results would be more promising if concurrent x-ray exposure were employed? [snip] Regards, Robin van Spaandonk http://rvanspaa.freehostia.com/project.html
