From: Eric Walker
Secondly, and most importantly - the neutron of the deuteron offers Coulomb shielding. Can you elaborate on this? I would have expected the neutron to be more or less invisible, as far as the Coulomb field is concerned. Eric Of course, the neutron looks to be neutral – from a distance, so it's not generally expected to shield anything massively in the same way that magnetism is shielded by a high mu metal or a dielectric shields against an electrostatic field. But both of those mechanisms may offer a clue. Unless, of course, the neutron has a significant dipole moment or a significant near-field charge, so that is aligns geometrically between the proton and the approaching nickel nucleus – to partially shield in the same way a dielectric would. The strong force is so much stronger than electrical repulsion, that any small effect can make a difference at close range. This may an open matter, as to whether current theory suggests the dipole moment of the neutron may be nonzero (does anyone know for sure?) but the neutron is reported to have a negative near-field, which means that it could provide some degree of shielding effect – certainly the electrostatic field lines are much different than with a bare proton. I do not have a handy reference for the proof of a neutron near-field, so this should be double checked. Jones
