Mirror core

from Wikipedia, the free encyclopedia

Mirror nuclei are pairs of atomic nuclei with exchanged ("mirrored") numbers of protons and neutrons . They therefore differ in their atomic number and thus represent two different chemical elements . Mirror nuclei are a special case of isobars .

Examples of mirror cores:

nuclide Mass number A Proton number Z Neutron number N characterization
22nd 10 12 straight-straight (gg) core
22nd 12 10 straight-straight (gg) core, radioactive
30th 14th 16 straight-straight (gg) core
30th 16 14th straight-straight (gg) core, radioactive
32 15th 17th odd-odd (uu) nucleus, radioactive
32 17th 15th odd-odd (uu) nucleus, radioactive
35 17th 18th odd-even (ug) core
35 18th 17th even-odd (gu) nucleus, radioactive

The mirror cores are interesting for comparative studies in nuclear physics . For example, in the Bethe-Weizsäcker formula the binding energies for mirror nuclei differ only in terms of the Coulomb component, which can then be examined in isolation.

At least one of the two mirror cores is always radioactive , and with the uu mirror cores both are always radioactive . With the exception of the pairs 1 n and 1 H and 3 H and 3 He , the nucleus with the higher number of protons is always radioactive.

Mirror cores show in an impressive way that protons and neutrons have different charges , but otherwise behave very similarly: energy levels as well as the corresponding spins and parities of mirror cores look very similar; the main difference is the energy of the ground state due to differences in the Coulomb potential .


  • Povh, Rith, Scholz, Zetsche: Particles and Cores , Springer, 4th edition 1997, ISBN 3-540-61737-X