From: Eric Walker
The nuclear force is very short range. Ø Here is where I'm inclined to part with conventional wisdom. Consider that 1 barn is the approximate area of a medium-sized nucleus presented to an oncoming neutron, that nuclei such as 135Xe have neutron-capture cross sections of 1e6 barns, and that with a neutron the Coulomb interaction is not involved. Eric – This is arguable not true. A degree of Coulomb interaction can be involved at close range with neutrons due to the spatial geometry of charge distribution. Don’t forget the neutron has a magnetic moment, and therefore has at least a near-field or segmented charge. Luis Alvarez discovered the neutron's magnetic moment many moons ago, and there is no doubt about this detail. Now consider at the implications of having magnetic moment and zero net charge. For a particle to have an intrinsic magnetic moment, it must have both spin and electric charge at some level. The neutron has half spin, but no net charge. Now– place the emphasis on the “net” in net charge… … so that when we consider that the neutron is composed of three charged quarks “no net charge” is a relative statement. Consequently, the smaller negative down quark charge (of two down quarks) is technically balanced by the larger up charge of one quark – but there is spatial imbalance at femtometers geometry of this charge due to the location of charge carriers vis-à-vis the center of mass. This is a charge imbalance at close range. A similar oddity is seen when a deuteron approaches another deuteron – there is a bit of geometric shielding of net positive repulsion which is provided by the neutrons of either nucleon, which only appears at close range.
