High-spin States In The Doubly Odd Nucleus¹⁰⁴Ag And The Near-spherical Nuclei^91,92Zr

In this dissertation, the new rotational bands of the doubly odd nucleus104Ag and the core excitations in the near-spherical nuclei91’92Zr have been experimentally investigated via the97Mo(11B,4nγ)104Ag and82Se(13C, χnγ)91,92Zr (x=4,3) fusion-evaporation reactions at E(11B)=50MeV and E(13C)=44MeV at the HI-13Tandem Accelerator of the China Institute of Atomic Energy (CIAE) in Beijing.Much revised level scheme of104Ag has been established with the observation of41new transitions. Now, the level scheme of104Ag includes lower-lying two-quasiparticle states and several higher-lying bands. Two positive-parity bands associated with the Ï€g-19/2(?)vd5/2and Ï€g-19/2(?) vg7/2configurations are extended significantly. Based on the comparison with the features of nuclear chirality, the two negative-parity bands are suggested as candidate chiral doublet bands with the Ï€g-19/2(?) vh11/2configuration. These observations lead to an attachment of coexistent features of the single-particle exciatation, electric-quadrupole and magnetic rotation, and nuclear chirality in104Ag.By the use of in-beam spectroscopic methods,13new transitions belonging to91Zr and19to92Zr have been observed. The high-spin states of91Zr and92Zr above the fully-aligned21/2+and (12+) states have been interpreted in terms of the88Sr core breaking. Comparison of the proton P3/2â†'P1/2excitation energies in91Zr and92Zr, the level structure differences indicate a possible reduction of the energy gap between the proton P3/2and p1/2orbitals in92Zr when one more neutron goes into the (d5/2/g7/2) orbital. Considering the available theoretical approaches that have been used in the A～90mass region, the reduction may be associated with the proton-neutron tensor force. Our work also shows the dramatic reduction of the neutron d5/2-g7/2shell gap when a proton pair is added into the g9/2orbital.