Final-state interactions in the 2H(d, pp)nn reaction

Abstract

Absolute coincidence cross sections for the 2H(d, pp)nn reaction were measured at E d = 23.15 MeV by detecting both protons at a small included angle to observe events with small p-p and n-n relative energies (ε pp and ε nn). Evidence for a double final-state interaction was obtained at( θ 1 = 18 δ, θ 2 = 36°) and (25°, 43°) where the yields were elevated above phase space at low ε nnand depressed below phase space at low ε pp. Watson-Migdal predictions, using accepted values of the effective range parameters for the singlet p-p and n-n interactions, gave reasonably good fits to the data except for the ε nn spectrum at (25°, 43°) which required an n-n scattering length a nn < −50 fm. Acceptable fits were also obtained with a double distorted-wave theory using computed p-p and n-n scattering wave functions, a Gaussian transition potential and Slaus-Van Oers deuteron wave functions.