Craig, I don't if this helps, but most metals tend to be relatively transparent to neutrons, due to the scattering cross-section which is caused by spin, not by anything related to charge. The Coulomb barrier is not involved AFIK with neutrons.
A few metals like cadmium will absorb neutrons of the correct velocity to nullify spin effects, but in general neutrons must be slowed way-down (thermalized) before they can interact with say nickel; and usually they easily would escape the reactor long before that happens unless they are extremely "cold" - low velocity. Thus the W&L "ULM", which because it is cold/slow can stay around longer and have a much better chance of an interaction. IOW the approaching neutron will only interact at a significant rate if it extraordinarily slow in velocity. Jones -----Original Message----- From: Craig Haynie Hello all! I've got a question that I believe you could help me with: I understand that the coulomb barrier is the point at which the Strong Force will become dominant, and overcome the natural repulsion of two nuclei as they are moved closer together. But can neutrons penetrate the coulomb barrier without any problem, since they are not repelled by the positive charge in the nucleus? Is this why the Widom-Larsen hypothesis posits the entry of weak neutrons into the nucleus? Craig Haynie Manchester, NH
