E1 STRENGTH FUNCTION FOR 2-NEUTRON HALO NUCLEI IN AN ANALYTICAL 3-BODY APPROACH

An analytical expression for the E1 strength function for two-neutron halo nuclei is derived in a three-body model. Yukawa type wavefunction s for the ground state and three-body plane waves for the final state were used. The expression reproduces the shape and the position of the maximum of the experimental strength function for Li-11 well. It is s hown that the exact expression can be approximated over a large energy range with a simple function by introducing an effective two-neutron separation energy. This provides a theoretical approach for quick esti mates of the E1 strength function for two-body halo nuclei.