Axil, your last comment about the energy of the electron/proton having to be "just right" and that "such precision doesn't happen in the real world", is probably wrong. The reason is Compton scattering. Not all, and in fact most, collisions are not a "direct hit" and result in a bounce of the particle with it giving up a portion of its energy to the atom that scattered it. Thus, if a high energy particle enters a region of dense atoms, it will scatter, losing energy gradually, with the energy being delivered into kinetic energy of the scattering atoms. So, there is a continuous range of energy that is available, as an initial high energy particle is Compton scattered in a dense atom field. At some point, it would seem that the energy of the particle will be "just right" for neutrino/anti-neutrino formation.
Bob Higgins On Thu, Apr 16, 2015 at 12:35 AM, Axil Axil <janap...@gmail.com> wrote: > If found another explanation about electron capture from an expert as > follows: > > See below for a "borrowed" explanation from Jim Swenson at the Argonne > National Labs (from their Ask A Scientist program): > > "If an electron with enough energy collides with a proton, then what > happens? > They just form a hydrogen atom? > Or they form a neutron? > If both are possible, then which factor controls the process? > I am asking because I heard that a neutron can decay to a proton and an > electron and the reverse is possible. > ----------------- > To form a hydrogen atom, it is required that the electron and proton have > almost no energy, almost no velocity relative to each other. A hydrogen > atom ionizes at less than 20 electron-volts of energy, so reverse > ionization requires energy less than about 20 electron-volts (eV) AND > freedom and luck to radiate a photon of the right energy to render the > electron "captured". It happens all the time in every electrified gas lamp > (fluorescents, neons, mercury-arc, etc), and in the surface layers of the > sun. > > When a neutron decays into a proton, electron, and neutrino, it also > releases energy, 780,000 eV, as the sum of the kinetic energy of the 3 > particles.It is unreasonably difficult to get 3 separate particles to > collide simultaneously, so the exact reverse of this never happens to a > significant extent. It is particularly difficult to get the ghost-like > neutrino to react on command with an electron and proton. Neutrinos are the > particles that sail all the way through the earth, almost never bumping > anything. > > However, it is not so difficult for a balanced neutrino / anti-neutrino > pair to be accidentally made out of pure excess energy, from the collision > between an electron and a proton. Then you have the situation of the > electron and proton and neutrino in the same place, merging to form a > neutron, and an anti-neutrino flying away free carrying any excess energy > (beyond the 780 keV that was needed to make up the neutron). I think this > is one of the processes which together make sun-sized masses of neutrons > when a neutron star is formed in a supernova explosion. Actually, in that > situation the electron and proton are steadily squeezed together by > pressure of others around them. Increasing pressure and temperature can > smoothly change the energy of repeated collisions until the best energy is > found, and the conversion becomes quite rapid and energy-efficient. > > If the excess energy of collision is over 1,000 keV, other random > particles might be made from the energy too. It only takes 1,020 keV to > make an electron-positron pair, for example. I'm not sure what it takes to > start emitting excess energy as gamma-ray photons. That might happen too. > > Jim Swenson" > > From this answer, we need a neutrino to be around and in the party when > the electron and the proton combine. That is not likely to happen unless > the neutrino is made out of energy. The chance of that neutrino production > from energy is the chance that the reaction will work. > > > The energy of a collision between an election and a proton must be real > close to 780,000 eV to happen. Such precision just don't happen in the real > world. The chance of that energy being just right is very low. If the > energy is not perfect, other particles will form instead or a gamma will > form. But the point that kills the electron capture idea as the driver of > the LENR reaction is that electron capture must happen 10^23 times a second > to make any heat. That is impossible. Not when the electrons are carrying > the energy of soft x-rays into the collision. > > >
