The 8He and 10He spectra studied in the (t,p) reaction
Abstract
The low-lying spectra of 8He and 10He nuclei were studied in the 3H(6He,p)8He and 3H(8He,p)10He transfer reactions. The 0+ ground state (g.s.) of 8He and excited states, 2+ at 3.6-3.9 MeV and (1+) at 5.3-5.5 MeV, were populated with cross sections of 200, 100-250, and 90-125 μb/sr, respectively. Some evidence for 8He state at about 7.5 MeV is obtained. We discuss a possible nature of the near-threshold anomaly above 2.14 MeV in 8He and relate it to the population of a 1- continuum (soft dipole excitation) with peak value at about 3 MeV. The lowest energy group of events in the 10He spectrum was observed at 3 MeV with a cross section of 140 μb/sr. We argue that this result is possibly consistent with the previously reported observation of 10He, in that case providing a new g.s. position for 10He at about 3 MeV.