Structure of neutron-rich beryllium and carbon isotopes

Abstract

Ogloblind, Ch. Schulzfl, S. Thummererfl aHahn-Meitner-Institut, Glienicker Strasse 100, 14109 Berlin, Germany bFlerov Laboratory of Nuclear Reactions, JINR, 141980 Dubna, Russia and Bulgarian Academy of Sciences, Sofia, Bulgaria ‚Dept. of Physics and Astronomy, Ohio University, Athens, Ohio 45701-2979, USA dInst. of General and Nuclear Physics, Kurchatov Institute, Moscow 123 182, Russia The structure of the neutron-rich isotopes 12Be, 16C and 17C has been studied using the (12C,gC) three-neutron transfer reaction on ™Be, 13C and 14C targets, respectively. Ex- cited states up to 17 MeV excitation energy were observed. In 16C and 17C the populated structures have a dominant (~d)~ neutron configuration, these are three-particles one-hole (3plh) states in 16C and three-particles zero-hole (3pOh) states in 17C. In 12Be a larger va- riety of configurations is expected. Besides the low-lying states with (2p2h) character, also odd parity (3p3h) configurations are populated. In addition, due to the pronounced a-n-a cluster structure of the ™Be ground state, molecular structures in I2Be with 6He+6He and 4He+8He configurations can be populated by the three-neutron transfer. 1. INTRODUCTION In neutron-rich Be- and C-isotopes the detailed structure of excited states is of strong interest, since pronounced a-cluster or even molecular structures as well as single-particle and particle-hole structures can be expected [l-31. To obtain more detailed experimental information, it is important to select appropriate reactions to populate in a direct way the distinct structures in the final nucleus: