deuterons

A deuteron is the nucleus of the isotope deuterium, symbolized as d or 2H. It consists of one proton and one neutron bound together by the nuclear strong force. The deuteron has a binding energy of about 2.224 MeV and a mass near 2.0136 atomic mass units. It carries a single positive electric charge and has total angular momentum J = 1 with positive parity, and its isospin is zero.

The ground-state structure of the deuteron is dominated by an S-wave (L = 0) two-nucleon configuration, with a small admixture of D-wave (L = 2) produced by the tensor component of the nucleon-nucleon interaction. This D-state admixture leads to a nonzero electric quadrupole moment, measured at about Qd ≈ 0.286 fm^2. The deuteron magnetic moment is μd ≈ 0.857 μN, reflecting contributions from both the proton and neutron.

Its root-mean-square radius is roughly 1.95 to 1.97 femtometers, making it a relatively extended and weakly bound system. The deuteron is the only bound state of two nucleons in free space; the dineutron and di-proton are not bound under normal conditions. Descriptions of its binding rely on nucleon-nucleon potentials, often modeled with meson exchange mechanisms such as pion exchange.

In science and applications, the deuteron plays a key role in both fundamental and applied contexts. It is central to Big Bang nucleosynthesis and stellar fusion as a stepping stone toward heavier elements, and it serves as a target and projectile in experiments probing nucleon-nucleon forces and reaction dynamics.