Mirror core

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
${\displaystyle {}_{10}^{22}\mathrm {Ne} }$	22nd	10	12	straight-straight (gg) core
${\displaystyle {}_{12}^{22}\mathrm {Mg} }$	22nd	12	10	straight-straight (gg) core, radioactive
${\displaystyle {}_{14}^{30}\mathrm {Si} }$	30th	14th	16	straight-straight (gg) core
${\displaystyle {}_{16}^{30}\mathrm {S} }$	30th	16	14th	straight-straight (gg) core, radioactive
${\displaystyle {}_{15}^{32}\mathrm {P} }$	32	15th	17th	odd-odd (uu) nucleus, radioactive
${\displaystyle {}_{17}^{32}\mathrm {Cl} }$	32	17th	15th	odd-odd (uu) nucleus, radioactive
${\displaystyle {}_{17}^{35}\mathrm {Cl} }$	35	17th	18th	odd-even (ug) core
${\displaystyle {}_{18}^{35}\mathrm {Ar} }$	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 .

literature

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