Two-spectator quasifree processes

Two-spectator quasifree processes (graphs with two spectator particles) for the 3He(3He,dd)pp reaction at the symmetric angle pairs theta = 30.10 at Esub(3He) = 50 MeV and theta = 370 at Esub(3He) = 78 MeV are investigated. The theoretical cross sections are calculated with the PWIA model. The measured cross sections are smaller but have shapes which are in good agreement with the calculation. The ratio N = experiment/theory is approximately 0.05 at 50 MeV and 0.1 at 78 MeV. The reaction 2H(d,pp)nn also was studied at the symmetric angle pair theta = 34.80 and Esub(2H) = 34.7 MeV and the ratio is about 0.14. (Auth.)