A Search for the Singlet Deuteron

Dr. Robert W. Hackenburg
Brookhaven National Laboratory

The deuteron has long been called “the hydrogen atom of nuclear physics”, because it represents the simplest nuclear bound state. The ordinary deuteron found in nature has total spin one (the triplet deuteron); it is a real, bound state of a neutron and proton. Its existence is largely responsible for the spin-one partial cross section in np scattering at low energies. The singlet deuteron, with spin zero, is classified as a so-called “virtual state”, and is largely responsible for the observed spin-zero np partial cross section at low energies. The concept of the virtual state, and its shortcomings, will be briefly discussed at an elementary level. Given that the singlet deuteron is below the np mass, it cannot decay to np, but should decay rapidly (3.2 fs) via gamma emission to the triplet deuteron. It should be observable as a resonance in gamma-deuteron elastic scattering, at 2.16 MeV, with a width of 0.2 eV and a peak cross section of about 1 mb, making it difficult to observe.