Neutron-neutron final state interactions in the reaction H(d, pp)2n

The reaction ²H(d, pp)2n has been studied at a bombarding energy of 12 MeV, detecting the two protons in coincidence at angles of ±20° as well as +20° and −15°. In both cases, a narrow band was observed in a three-dimensional plot of the yield versus the energies of the two detected protons. E1 and E2, with most of the yield concentrated in the area where E1 ≈ E2. This suggests a two-step sequential process of the type d + d → (2p) + (2n) → p + p + n + n. In a missing mass plot for the third, undetected “particle” a pronounced, narrow peak appears at low relative energies in the (nn) system.