RUI: Experimental Studies of N=Z Nuclei Near 72Kr

Nuclei with equal numbers of neutrons and protons near 72Kr provide interesting and important tests of nuclear theory, as they can supply information on the interaction of neutron-proton (np) pairs, and test our understanding of the evolution of nuclear shape. Recently, two possible consequences of np pairing have been offered: a delay in the rotational frequency at which nucleon pairs break and align with the angular momentum of the core, and the apparent low level density of odd-odd N=Z nuclei. The primary focus of this work is the collection, analysis and interpretation of data on low-spin states in the odd-odd nuclei 74Rb and 88Y, of which little or nothing is known. The experiments will be carried out at Argonne National Laboratory (ANL) using the Gammasphere array, an array of neutron detectors, and the Argonne Fragment Mass Analyzer (FMA). A secondary focus of this work is on studies of the nucleus 72Kr, including a low-spin experiment using the Gammasphere array coupled to the FMA. The goal of this experiment is to observe and characterize the states at low excitation energy and angular momentum, including the expected continuation of an oblate band that has remained elusive through the years. This work will be done with the support of two undergraduate research assistants who will have the opportunity to participate in the setup of experiments, and the collection and analysis of the data.