Search for the excited states of neutron-rich krypton isotopes

Abstract

The complex nature of nuclear structure is governed by strongly interacting nucleons. As described by the nuclear Shell Model, the building blocks of atomic nuclei, protons and neutrons, arrange themselves in discrete quantized orbitals that group into shells. These shells are considered closed when the number of protons or neutrons equate to the magic nucleon numbers. In neutron-rich nuclei which are created via the r-process in nature's neutron-rich environments, expectedly, potential changes in shell structure and magic numbers is discussed theoretically. Identifying shell closures in neutron-rich isotopes would help constrain theoretical models for r-process nucleosynthesis. Krypton isotopes are of interest as current experimental evidence points towards changes in shell structure taking place in the neutron-rich region of N=50-60. Following the trend of the neighbouring elements, Sr and Zr, there is potential of shape coexistence manifesting in these Kr isotopes. Such a discovery will help provide further information on the nuclear force which governs the evolution of nuclear structure. Therefore, the excited states of select Kr nuclei were investigated to provide further data on the shell structure of neutron-rich isotopes. To investigate this neutron-rich region, a beam of ⁹³Kr was received at the IRIS reaction spectroscopy station located at TRIUMF. Through the use of a solid deuterium target, both the reaction channels ⁹³Kr(d,d)⁹³Kr and ⁹³Kr(d,p)⁹⁴Kr were investigated.