Research On High Spin States And Isomers In Odd-A Ru Nuclei

By measuring high-fold prompt γ-ray coincidence events following the spontaneous fission of 252Cf, the high spin states in very neutron-rich 113Ru nucleus have been studied. Furthermore, some isomers in neutron-rich odd-A nuclei 107,109,111,113Ru have been analyzed.The experiment was carried out at the Lawrence Berkeley National Laboratory (U.S.A). A 252Cf was placed at the center of the Gammasphere detector array which, for this experiment, consisted of 102 Compton-suppressed Ge detectors. By measuring prompt γ-ray of spontaneous fission from 252Cf, a total of 5.7×1011 triple- and higher-fold coincidence events were collected. The coincidence data were analyzed with the Radware software package. Through identifying the transitions in the double-gated spectrum by program of XMLEV, we have built the level scheme with high spin states for 113Ru for the first time. An intruder collective band associated with the h11/2 neutron excitation has been identified with spin up to 31/2 ? and excitation energy 3.6 MeV. Another weak collective band based on 9/2- level has also been observed. Three crossover weak transitions between these two bands were observed. Furthermore, some characteristics of the collective bands of the odd-A Ru nuclei have been systematically discussed. Particle-Rotor Model calculation has been carried out and the culculated results agree with the experiment data well. Additionally, we have investigated isomers in neutron-rich nuclei. The analyzing method has been explored. Using our technique, some lifetimes of levels in 107,109,111,113Ru with low excited energy were analyzed and some new lifetimes of the levels have been discoverd.