Exploration of Charge Dependence in the Strong Nuclear Interaction

Synopsis

In nuclear theory it is assumed that the strong interaction is independent of electric charge. Like many assumptions, this independence fails under close scrutiny. To this end, experiment S1758 at TRIUMF explores the charge dependence of the strong nuclear interaction using the combined apparatus developed by TRIUMF and SFU. Some novel energy/spin states for Nickel-55 and Cobalt-55 may be produced by impinging beams of radioactive Sodium-20 and stable Neon-20 upon Calcium-40, respectively. Nickel-55 and Cobalt-55 are known as mirror nuclei due to their similarity in structure when their neutron and proton numbers are exchanged. Under the principle of electric charge independence, underlying structure differences for these mirror nuclei are easily resolved with electromagnetic forces. This principle is known as mirror symmetry. However, it is expected that this symmetry breaks down due to the strong interaction's electric charge dependence. Probing this symmetry will unlock new information that allows for progress toward a currently non-existent overarching theory for the strong interaction. This presentation will include an introduction to nuclear theory and the TRIUMF facility before focusing on the steps taken thus far to explore the mirror symmetry between Nickel-55 and Cobalt-55.