Mirror nuclei

Mirror nuclei are nuclei where the number of protons of element one (Z1) equals the number of neutrons of element two (N2) and the number of protons of element two (Z2) equals the number of neutrons in element one (N1), such that the mass number is the same (A = N1 + Z1 = N2 + Z2).

Nuclear physics
Nucleus · Nucleons (p, n) · Nuclear matter · Nuclear force · Nuclear structure · Nuclear reaction

As that Z1 = N2 and Z2 = N1, A = N1 + N2 = Z1 + Z2. By making the substitution Z1 = Z and Z2 = Z − 1, the mass number can be rewritten in the form 2Z - 1.

Examples of mirror nuclei:

  • 3H and 3He:   Jπ =  1/2+
  • 14C and 14O:   Jπ =  0+
  • 15N and 15O:   Jπ =  1/2−
  • 24Na and 24Al:   Jπ =  4+
  • 24mNa and 24mAl:   Jπ =  1+

Pairs of mirror nuclei have the same spin and parity. If we constrain to odd number of nucleons (A=Z+N) then we find mirror nuclei that differ from one another by exchanging a proton by a neutron. Interesting to observe is their binding energy which is mainly due to the strong interaction and also due to Coulomb interaction. Since the strong interaction is invariant to protons and neutrons one can expect these mirror nuclei to have very similar binding energies.[1][2]

In 2020 Strontium-73 and bromine-73 were found to not behave as expected.[3]

References
  1. Cottle, P. D. (2002-04-12). "Excitations in the Mirror Nuclei 32Ar and 32Si". Physical Review Letters. 88 (17): 172502. Bibcode:2002PhRvL..88q2502C. doi:10.1103/PhysRevLett.88.172502. PMID 12005747. Retrieved 2018-01-08.
  2. Kamat, Sharmila (2002-04-23). "Focus: Gazing into a Nuclear Mirror". Physics. American Physical Society. Retrieved 2016-04-11.
  3. Discovery by UMass Lowell-led team challenges nuclear theory
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