Nuclear Shell Model and Spin-Orbit Interaction |
In the liquid drop model wehave emphasized the properties of nuclear matter have said nothing about singlenucleons. This is a great departure from the atomic model where the emphasis ison the motion of the electron in the field provided by the nucleus. Nowquestions are: Can nucleons be existed in well-ordered controlled nuclearshell? Is there any evidence for thegrouping of nucleons into shells? Can quantum number similar to n, l, s, j be applied to the nucleus? Forcertain numbers of neutrons or protons, calledmagic numbers, nuclei exhibit special characteristics of stabilityreminiscent of the properties shown by noble gases among the atoms. Nuclei inwhich either N or Z is equal to oneof these magic numbers (2, 8, 20, 28, 50, 82, 126, 184) show certainparticulars that are not understandable in terms or the liquid drop model. Wewill see that the magic numbers of the nucleons can be explained with a shellmodel of the nucleus. Evidently protons and neutrons in the nucleus are not allequivalent as had been assumed in introducing the liquid drop model.