Influence of Neutron Core Excitations on the High-Spin States of 88Sr

High-spin states of 88 Sr have been investigated via the reaction 80 Se(11 B,p2n) at the beam energy of 45 MeV. Gamma-rays have been detected with the six-detector array OSIRIS CUBE. The level scheme of 88 Sr has been extended up to the spin J=17 at 11.4 MeV. Using the Doppler-shift attenuation method, mean lifetimes of 3 levels have been obtained. Shell-model calculations in the model space (0f5/2, 1p3/2, 1p1/2, 0g9/2) for the protons and (1p1/2, 0g9/2, 1d5/2) for the neutrons have been performed to interpret the high-spin structure of this nucleus. As a neutron-core break up is expected at about 4 MeV, the core excitation of one neutron from the 0g9/2 orbital to the 1d5/2 orbital is included. The structure of level sequences at high spin including strong M1 transitions (B(M1)≥ 0.3) is discussed. (authors)