First measurement of the 2.4 MeV and 2.9 MeV 6He three-cluster resonant states via the 3H(4He, pα)2n four-body reaction

Abstract

Two new low-lying 6 He levels at excitation energies of about 2.4 MeV and 2.9 MeV were observed in the experimental investigation of the p-α coincidence spectra obtained by the 3 H (4 He , p α)2 n four-body reaction at E4 He beam energy of 27.2 MeV. The relevant E* peak energy and Γ energy width spectroscopic parameters for such 6 He * excited states decaying into the α+ n+n channel were obtained by analyzing the bidimensional (E p , Eα) energy spectra. The present new result of two low-lying 6 He * excited states above the 4 He +2 n threshold energy of 0.974 MeV is important for the investigation of the nuclear structure of neutron-rich light nuclei and also as a basic test for theoretical models in the study of the three-cluster resonance feature of 6 He .