Production of Very Neutron-rich Nuclei with Low Energy Beam

The production cross section of very neutron-rich nuclei, $^{8} $He, has been investigated using multi-nucleon transfer reaction with a $^{9}$Be beam at 14 MeV/nucleon. The cross section data will be used to optimize the produced neutron-rich nuclei beam for the study of nuclear structure. The experiment was performed at ATLAS facility at Argonne, where the $^{9}$Be beam bombarded production targets of Be, BN, C, and U. Particle identification of reaction products was carried out by means of the magnetic split-pole-spectrograph with a focal plane detector that consists of PPAC’s and ion chambers. The momentum distribution of 8He yield was measured by varying the magnetic field. The angular distribution was measured at 0 and 5 degree. The production cross section was obtained for integration of the observed yield for each target. The production cross section of the $^{9}$Be ($^{9}$Be, $^{8} $He) X reaction is smaller than that of the $^{238}$U ($^{9}$Be, $^{8}$He) X by one order of magnitude. In the present talk, we will report details of the experiment and discuss the production mechanism of neutron-rich nuclei with low energy beams.