Low-energy dipole excitation modes in Be

Abstract

Low-energy dipole excitations in 10Be were investigated based on the generator coordinate method with ?+6He and ?+?+2n cluster models.We obtained three 1? states in Ex 15MeV, which show different characters in the E1, compressive dipole, and toroidal dipole transition strengths.We found the strong toroidal dipole transition in the 1? 1 state, remarkable E1 strength in the 1? 2 state, and the strong E1 and compressive dipole strength in the 1? 3 state. The 1? 1 is described by the ? + 6He cluster structure, whereas the 1? 2 and 1? 3 states are understood by three-body excitations of the ? + ? + 2n clustering.