Influence of Electronic Media on the Reading Habits of Pupils |
The study of nuclear properties shows evidence of nuclearshells analogous to those observed in the atoms. One clear piece of evidence inthe nuclear case is the sharp discontinuity in nucleon separation energies forcertain numbers of N (neutron number) and Z (proton number), known as magicnumbers. In the case of the electronic shells in atoms the picture is veryclear, since there is a central Coulomb potential, due to the charge carried bythe nucleus and electrons. In the case of the nucleus there is no such externalpotential but the nucleons move in the potential created by them selves. Thispotential contains many terms: central, spin-orbit, tensor, spinspin, etc. Atlong distances it has a Yukawa form , while at short distances it shows anextremely repulsive core. The idea of a shell model for the nucleus may seemcontradictory with these strong correlations because this rudely breaks theindependent particle picture.