Nuclear Structure Studies Based on the Lifetime Measurements of Excited States in Nuclei at the in-beam γ Terminal of HI-13 Tandem Accelerator

The significance and principle of lifetime measurements of excited states in nuclei are briefly described. By using the recoil-distance Doppler-shift method, the Doppler-shift attenuation method, and the fast-timing technique established at the in-beam γ terminal of HI-13 tandem accelerator, nuclear structure studies on topical subjects including chiral symmetries and magnetic rotation have been performed. Our experimental results indicate that ¹³⁰Cs shows better chiral characteristics, however, the two candidate bands of ¹⁰⁶Ag could not be a pair of chiral doublet bands. For magnetic rotation, the deduced B(M1) values deduced from the measured level lifetimes clearly demonstrate that the yrast positive-parity band in ¹⁰⁶Ag and both the yrast positiveand negative-parity bands in ¹⁰⁷Ag are magnetic rotation bands. In addition, our lifetime measurement data also provide valuable experimental evidences for the interpretation and understanding of the shape evolution, the shape coexistence, and the critical-point symmetries of shape phase transition in the different isotope chains.