This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.Find sources: "Mirror nuclei" – news · newspapers · books · scholar · JSTOR (February 2013) (Learn how and when to remove this template message)

In physics, mirror nuclei are a pair of isotopes of two different elements where the number of protons of isotope one (Z1) equals the number of neutrons of isotope two (N2) and the number of protons of isotope two (Z2) equals the number of neutrons in isotope one (N1); in short: Z1 = N2 and Z2 = N1. This implies that the mass numbers of the isotopes are the same: N1 + Z1 = N2 + Z2.

Examples of mirror nuclei:

Isotope 1 Z1 N1 Isotope 2 Z2 N2
3H 1 2 3He 2 1
14C 6 8 14O 8 6
15N 7 8 15O 8 7
24Na 11 13 24Al 13 11

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]


  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