Experimental investigation of highly excited states of the 5,6He and 5,6Li nuclei in the (6Li, 7Be) and (6Li, 7Li) one-nucleon pickup reactions

Abstract

The (6Li, 7Be) and (6Li, 7Li) reactions on 6Li and 7Li nuclei were investigated in the angular interval 0°–20° in the laboratory system at a 6Li energy of 93 MeV. In addition to low-lying states of the 5,6He and 5,6Li nuclei, broad structures were observed near the t(3He)+d and t(3He)+t thresholds at the excitation energies of 16.75 (3/2+) and ∼20 MeV (for 5He), 16.66 (3/2+) and ∼20 MeV (5Li), 14.0 and 25 MeV (6He), and ∼20 MeV (6Li). The angular distributions measured in the 7Li(6Li, 7Be)6He reaction for transitions to the ground state (0+) and excited states at Ex=1.8 MeV (2+) and 14.0 MeV of the 6He nucleus were analyzed by the finite-range distorted-wave method assuming the 1p-and 1s-proton pickup mechanism. The (6Li, 7Be) and (6Li, 7Li) reactions were shown to proceed predominantly through the one-step pickup mechanism, and the broad structures observed at high excitation energies are considered as quasimolecular states of the t(3He)+d and t(3He)+t types.