Experimental Study of ？β-delayed Proton Decays of 145,147Er
At the Institute of Modern Physics, CAS，the very neutron-deficient nuclei 145,147Er were produced via the reaction of 58Ni+92Mo at beam energy of 383 MeV. Using the He-jet apparatus coupled with a tape transport system, the b-delayed proton radioactivities both from the ns1/2 ground state and the nh11/2 isomer in 145,147Er were observed by proton-g coincidence measurements. The decay schemes of 145,147Er, deduced from this work, are shown in Fig.1.
Fig. 1. Decay schemes of (a) 145Er and (b) 147Er
The calculation of the statistical model indicated that the 4+ states in the granddaughter nuclei 144,146Dy were mainly produced by the b-delayed proton decays of the nh11/2 isomers in 145,147Er. Therefore, the half-lives of the isomers in 145,147Er can be obtained by analyzing the time distributions of the 4+→2+ g transitions in 144,146Dy. As shown in Fig.2, the half-lives of 1.0 ± 0.3 s and 1.6 ± 0.2 s have been deduced for the nh11/2 isomers in 145,147Er by fitting the decay curves of the 673 and 926 keV transitions, respectively. The results were published in Physical Review C81,047301(2010)。
Fig. 2. Delayed proton spectra gated by the (a) 673 keV and (b) 926 keV transitions and their decay curves.