MRI: Development of a Unique Ion Trapping System to Test the Standard Model of Physics at the Nuclear Science Laboratory

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The human need to understand the inner workings of our universe has driven scientific questions both at the elementary level and at astronomical scales prompting the establishment of the Standard Model (SM), one of the cornerstone theories of physics that successfully predicted the Higgs boson. This theory however fails to reproduce many unexplained features of our visible universe, which currently prompts several different searches at the energy, intensity, and precision frontiers. By performing very precise measurements of fundamental quantities related to a special case of radioactive decay, one can probe for physics not included in the SM. The funds from this Major Research Instrumentation (MRI) grant will support the construction of an ion trapping apparatus, called NSLtrap, that will hold radioactive nuclei unimpeded in free space, allowing these delicate measurements to be performed. The research done with this instrument will raise the possibility of discovering physics beyond the SM, which could open wide new avenues for theoretical, experimental, and fundamental research. At the same time the development and operation of NSLtrap will train some of America's future scientific workforce in various aspects of research and development, including computation, design, assembly, troubleshooting, data gathering, data analysis and the dissemination of results. The skills acquired by the students will be transferable to careers that can advance the national health, prosperity and security. The NSLtrap project will aim at testing the Standard Model by providing a more stringent test of the Cabibbo-Kobayashi-Maskawa (CKM) matrix unitarity that relates the weak interaction and mass eigenstates of the quarks. The largest matrix element, Vud, can be extracted from four types of decay: pion decay, neutron decay, superallowed mixed decay, and superallowed pure Fermi decay transitions. Despite the high precision achieved in the pure Fermi decay studies, there is currently a growing interest in the other transitions to test the accuracy of Vud. The NSLtrap project plan is to expand the ensemble of mirror transitions from which the conserved vector current (CVC) hypothesis can be tested and Vud extracted by measuring a missing quantity called the Fermi-to-Gamow Teller mixing ratio. As a result, the more precise extraction of Vud from mirror transitions will create further constraints on the Vud matrix element determination from pure Fermi decays, improving its accuracy.