paringsenergi

Paringsenergi, or pairing energy, is a term used in physics to describe the energy gained when two fermions form a bound pair due to an attractive interaction. It appears prominently in nuclear physics and in condensed matter physics.

In atomic nuclei, nucleons tend to pair up; protons pair with protons and neutrons with neutrons. This pairing lowers the total binding energy, making even-even nuclei typically more bound than neighboring odd-A or odd-odd nuclei. The resulting odd-even staggering of nuclear masses and binding energies is a signature of pairing energy. The pairing energy is commonly estimated from mass differences and is often expressed as a pairing gap, with typical values of around 1 MeV for nucleon pairs in mid-mass nuclei.

In superconductors, Cooper pairs form a many-body ground state; the pairing energy manifests as an energy gap Δ in the single-particle excitation spectrum. The energy required to break a Cooper pair equals the gap; Δ decreases with temperature and vanishes at the critical temperature Tc. In BCS theory, Δ is related to the strength of the attractive interaction and the density of states at the Fermi level.

Measurement and interpretation vary by field. In nuclear physics, pairing energy is inferred from precise mass measurements and theoretical mass models, often via odd-even mass differences. In superconductivity, the pairing energy is probed by tunneling spectroscopy, optical conductivity, and heat capacity measurements, linking the microscopic pairing to macroscopic superconducting properties.