Transition probabilities and the structure of some negative-parity states in 126,130Xe and 132Ba

Abstract

The lifetimes of several negative-parity states in 126,130Xe and 132Ba have been determined by means of the generalized centroid-shift method. The reactions 124,128Te(α, 2n) and 122Sn(13C, 3n) have been used. Following results were obtained: T1/2(2758 keV) = 1.3 ± 0.2 ns in 126Xe, T1/2 (2060 keV) = 0.20 ± 0.10 ns, T1/2 (2104 keV) = 0.50 ± 0.10 ns, T1/2 (2376 keV) = 0.30 ± 0.10 ns and T1/2 (2973 keV) = 4.6 ± 0.4 ns in 130Xe as well as T1/2(2120 keV) = 0.40−0.10+0.20 ns in 132Ba. A systematics of the B(E2; 71− ⇒ 51−) values in the N = 76 nuclei is presented. Electric dipole and quadrupole transition rates are discussed in terms of octupole and quadrupole collectivity. The structure of the 51− and 71− states is considered. Nuclear reactions: 124,128Te(α, 2n), E = 26 MeV, 122Sn (13C, 3n), E = 53 MeV; measured E{gg}, I{gg}, γ-r.f. Deduced T1/2, B(σL) in 126,130Xe and 132Ba. Ge detectors. Generalized centroid-shift analysis.