Exploration of Structures in the Transitional Odd-Odd Nucleus Lu-160.

摘要

Contrary to popular belief, not all nuclei are spherical. Past studies have determined that shells fill at certain "magic numbers" of nucleons when either the proton number (Z) or the neutron number (N) of the nucleus is, among other values, 82. The farther away a nucleus' Z or N is from these magic numbers, the more deformed it will be. Lutetium has 71 protons (Z = 71). A wide variety of isotopes of lutetium exist, which have the same Z but different N. As such, the transition between generally spherical lutetium nuclei and generally non-spherical nuclei occurs between N = 86 and N = 90, where Lu-160 (N = 89) lies. This project aimed to investigate the structure of such a transitional nucleus. The study required creating rapidly-spinning Lu-160 nuclei by means of a particle accelerator at Argonne National Laboratory. Once excited, an instrument called Gammasphere was employed to capture information about the high-energy photons. Experimental evidence showed abnormal signature splitting behavior in Lu-160. We believe this behavior is due to an alignment gain in Lu-160 that is hidden in its more rigid neighbors. The transitional nature of Lu-160 leaves it more susceptible to shape-driving effects of given nucleons, and allows for the additional malleability required to manifest this alignment gain which influences the nucleus' signature splitting.