In nuclear physics, the nuclear shell model is a model of the atomic nucleus. It is analogous to the atomic shell model that is more familiar to those who have studied basic physics. Recall that in the atomic shell model, the electrons populate shells, and once a shell is filled, there is a significant drop in the binding energy for the next electron added. Nuclear physics is the branch of physics concerned with the nucleus of the atom. ... A semi-accurate depiction of the helium atom. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... The first few hydrogen atom electron orbitals shown as cross-sections with color-coded probability density. ... Properties The electron is a lightweight fundamental subatomic particle that carries a negative electric charge. ...

It is similar for the nuclear shell model. When adding nucleons (protons or neutrons) to a nucleus, there are certain points where the binding energy of the next nucleon is significantly less than the last one. This observation, that there are certain magic numbers of nucleons: 2, 8, 20, 28, 50, 82, 126 which are more tightly bound than the next higher number, is the origin of the shell model. In nuclear physics, a magic number is a number of nucleons such that they are arranged into complete shells within the atomic nucleus. ...

Note that the shells exist for both protons and neutrons individually, so that we can speak of "magic nuclei" where one nucleon type is at a magic number, and "doubly magic nuclei", where both are. Due to some variations in orbital filling, the upper magic numbers are 126 and, speculatively, 184 for neutrons but only 114 for protons. This has a relevant role in the search of the so-called island of stability. Besides, there have been found some semimagic numbers, noticeably Z=40. Properties [1][2] In physics, the proton (Greek proton = first) is a subatomic particle with an electric charge of one positive fundamental unit (1. ... This article or section does not cite its references or sources. ... 3-dimensional rendering of the theoretical Island of Stability. ...

In order to get these numbers, the nuclear shell model starts from an average potential with a shape something between the square well and the harmonic oscillator. To this potential a relativistic spin orbit term is added. Even so, the total perturbation does not coincide with experiment, and an empirical spin orbit coupling, named Nilsson Term, must be added with at least two or three different values of its coupling constant, depending on the nuclei being studied.

See also

• Interacting boson model
• Liquid drop model
• Moon nuclear model

The Interacting Boson Model (IBM) is a model in nuclear physics in which nucleons (protons or neutrons) pair up, essentially acting as a single particle with boson properties, with integral spin of 0, 2 or 4. ... The liquid drop model is a model in nuclear physics which treats the nucleus as a drop of incompressible nuclear fluid, first proposed by George Gamow. ... The Moon nuclear model is a model in nuclear physics hypothesized in 1986 by Dr. Robert J. Moon (1911-1989), in which protons are considered to be located at the vertices of a nested structure of four of the five Platonic solids, in a similar way to that conceived by...

External links

• The Lamb's Balance, a proposed mechanism to substitute Nilsson terms.

• Nuclear Shell Model