Coulomb barrier

As Coulombwall or Coulomb potential is called, against which a positively charged particle must start to get into the likewise positively charged atomic nucleus. This potential is based on the Coulomb force (named after Charles Augustin de Coulomb ), which is repulsive between two electric charges of the same sign.

To overcome the barrier a minimum energy needed by the particles of classical mechanics. According to quantum mechanics, however, is also at a lower particle energy is a certain chance of tunneling through such a barrier.

Ernest Rutherford observed first that alpha radiation - which consists of positively charged particles - overcoming the barrier of atomic nuclei and thus can trigger nuclear reactions. Such experiments gave the first indications of components and structure of atomic nuclei.

To the discovery of quarks and gluons postulation of overcoming the Coulomb barrier of the proton was necessary.

The potential in the nucleus and in its vicinity is determined by the electromagnetic and the "strong " interaction. The long-range electromagnetic interaction effects (here in the form of the aforementioned Coulomb ) a repulsive potential at large distances. At small distances, however, the short-range strong interaction for an attractive nuclear potential makes and thus determines the magnitude of the atomic nucleus. The summation of these two effects results in a binding or quasi -binding potential.

The effective height of Coulombwalls depends not only on the charge of the nucleus and the load of the incoming particle and from the angular momentum of the incoming particle.

The finite amount of Coulombwalls explains the alpha decay of certain atomic nuclei.

Calculation

The height of the Coulombwalls is:

Approximation, it can be determined in MeV with the following rule:

Therein Z1 and Z2 are the atomic numbers of the projectile and the target, and A is the mass number of the target.

Trivia

The "Am Coulombwall " in Garching near Munich, was named after the Coulombwall.