NEW MEASUREMENTS OF THE MASS OF ISOTOPE H-4 IN REACTIONS WITH A RADIOACTIVE HE-6 BEAM AND LI-6 IONS

The cross sections of the reaction D(He-6, alpha) at E6(He) = 19.3 MeV were measured for the first time. Two resonances were observed in the alpha particle spectrum. The resonances correspond to the ground and excited states of the nuclear-unstable isotope H-4 that lie 2.0+/-0.3 MeV and 5.2+/-0.5 MeV above the H-4 -->t+n dissociation threshold. It is assumed that the excited state of H-4 has the configuration (d+ (2) n) and the quantum characteristics 1(+). The nuclear instability of H- 4 (2.3+/-0.3 MeV) is confirmed by measurements of the reaction Li-6((L iB)-Li-6-B-8) at the energies E6(Li) = 85 and 93 MeV. As a result, a n ew value is obtained for the H-4 mass defect: 25.3+/-0.3 MeV. (C) 1995 American Institute of Physics.