Eric, Great work. Thanks.
I was not aware that official data was imprecise. Nice to know that. If the thermal neutron generation is actually occurring, it seems there should be a small amount of radioactive ash (maybe short-lived) after the reaction is stopped. I believe some of the sonofusion experiments report this. I do not know if these reports are reliable. As far as build up of Ni59 - Perhaps its cross section guarantees that it lasts only for a short time in the reaction chain before converting to copper. Also, in most experiments, the liquid of the Ni-nanoparticle emulsion may have a significant impact. Cheers, Lou Pagnucco Eric Walker wrote: > On Sat, Mar 23, 2013 at 5:11 PM, <[email protected]> wrote: > > Then you should be able to follow the same procedure, but include all the >> natural isotopes, no? >> > > I've gone back and corrected the calculation to take into account the > missing isotopes. This time I obtained upper and lower bounds for the > total cross section, from both Robin's Web site [1] and Lou's site [2], > and > I did the calculation using Robin's method along with a modified version > of > that method. > > Here are the estimated upper and lower bounds for the total neutron cross > sections for nickel as it is found in its natural isotopic abundances. > The > combined cross sections are the weighted values of the cross sections for > individual isotopes of nickel. > > UB Kaeri: 206 barns > LB Kaeri: 45 barns > UB NDS: 94 barns > LB NDS: 29 barns > > On the basis of these cross sections, I calculated the upper and lower > bounds for the transmitted fraction of an incident beam of neutrons at 1mm > and 10mm, using Robin's approach as well as a modified version of Robin's > approach relying upon the mean free path described in Wikipedia's article > on the neutron capture cross section [3]. The two sets of calculations > agreed to within two degrees of precision, which was nice to see. Since > they agreed, I'll just give the transmitted percentages using Robin's > approach: > > UB, 1mm: 76.6 percent > LB, 1mm: 15.2 percent > UB, 10mm: 7 percent > LB, 10mm: small > > For 1W of power being generated by way of neutron capture, assuming around > 10 MeV per capture, there would be about 624 billion neutrons generated > per > second. The number of neutrons per second that would be transmitted > through 1mm and 10mm of inactive nickel shielding would be: > > UB, 1mm: 478 billion > LB, 1mm: 94 billion > UB, 10mm: 43 billion > LB, 10mm: 4000 > > This assumes that there are no neutrons being generated in the nickel > shielding surrounding the active core, an assumption that runs counter to > conjecture that LENR (in Pd/D) is a surface effect. > > An interesting thing that I discovered as I was looking into this was that > Robin's Web site and Lou's Web site disagree significantly on what happens > to the total cross sections when the energies are small. In general, > Robin's Web site gave values that were well below the maximums, at around > 10E-4 MeV, while Lou's site gave values that were highest at the very > lowest energies, around 10E-10 MeV. I'm not sure what was going on there. > Just to be safe, the above calculations make use of both the cross > sections at the lowest energies as well as the maximum values for the > cross > sections. > > It interesting to note that the combined cross section can be expected to > go way up as 58Ni transmutes to 59Ni, which normally exists in trace > amounts but would build up over time, as 59Ni has an extremely large > neutron capture cross section. Note that nickel would become dangerously > radioactive over time as it was activated under this kind of neutron flux. > > Eric > > > [1] http://atom.kaeri.re.kr/ > [2] http://www-nds.iaea.org/ngatlas2/ > [3] http://en.wikipedia.org/wiki/Neutron_cross_section >
