Isovector Quadrupole Excitations in the Valence Shell studied in Projectile Coulomb Excitation

Abstract

One-phonon states of heavy vibrational nuclei with mixed proton-neutron symmetry have recently been made accessible by the technique of projectile Coulomb excitation. Gamma-rays following Coulomb excitation of the nuclides 136,138 Ce and 134 Xe have been measured with the Gammasphere-array run in singles-mode. M 1, E 2, and E 3 transition matrix elements from low-spin states were measured relative to the known B ( E 2 ; 0 1 + → 2 1 + ) values. The 2 + → 2 1 + M 1 strength distributions up to about 2.7 MeV serve for identifying the main fragment of the 2 1 , ms + one-quadrupole phonon mixed-symmetry state. The data are presented and their significance is discussed.