Polarized neutrons of energies 2 meV – 15 meV are incident on a liquid parahydrogen target. The neutrons are captured, forming deuterium and releasing a gamma ray with an energy of 2.2 MeV (the binding energy of deuterium), which is subsequently detected. The detector array consists of 4 rings of 12 detectors each, where each ring is concentric around the neutron beam. The polarization of the incoming neutron beam is alternated rapidly to study the spin correlation of the direction of the emitted gamma ray.