In
physics
Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...
, mirror nuclei are a pair of
isotopes
Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) ...
of two different
elements where the number of protons of isotope one (Z
1) equals the number of neutrons of isotope two (N
2) and the number of protons of isotope two (Z
2) equals the number of neutrons in isotope one (N
1); in short: Z
1 = N
2 and Z
2 = N
1. This implies that the mass numbers of the isotopes are the same: N
1 + Z
1 = N
2 + Z
2.
Examples of mirror nuclei:
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
The neutron is a subatomic particle, symbol or , which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons beh ...
. Interesting to observe is their binding energy which is mainly due to the strong interaction and also due to
Coulomb interaction
Coulomb's inverse-square law, or simply Coulomb's law, is an experimental law of physics that quantifies the amount of force between two stationary, electrically charged particles. The electric force between charged bodies at rest is convention ...
. Since the strong interaction is invariant to protons and neutrons one can expect these mirror nuclei to have very similar
binding energies
In physics and chemistry, binding energy is the smallest amount of energy required to remove a particle from a system of particles or to disassemble a system of particles into individual parts. In the former meaning the term is predominantly use ...
.
In 2020 Strontium-73 and bromine-73 were found to not behave as expected.
''Discovery by UMass Lowell-led team challenges nuclear theory''
/ref>
References
{{DEFAULTSORT:Mirror Nuclei
Atomic physics