Experimental Investigation of Highly Excited States of the ~(5,6)He and ~(5,6)Li Nuclei in the (~6Li, ~7Be) and (~6Li, ~7Li) One-Nucleon Pickup Reactions

摘要

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 ~(5,6)He and ~(5,6)Li 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 E_x = 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.