Accelerator Science for Storage Ring Measurements of Electric Dipole Moments of Subatomic Particles

Michigan State University, East Lansing MI

Investigators

Abstract

Overview One of the major intellectual achievements of the 20th century was the development of the Standard Model (SM) of particle physics. This model succeeded in classifying all of the elementary particles known at the time into a hierarchy of groups having similar quantum properties. The validity of this model to date was recently confirmed by the discovery of the Higgs boson at the Large Hadron Collider at CERN. However, the Standard Model as it currently exists, leaves open many questions about the universe. These include why matter dominates over anti-matter in the universe, the values of the masses of the fundamental constituents, the quarks and the leptons, the size of the mixings among the quarks, and separately among the leptons, and the properties of dark matter. Most explanations require the presence of new forces, which we call Beyond the Standard Model Physics (BSM). One of the promising techniques to look for BSM physics is to make precision measurements using standard particles like electrons and muons. One technique, in particular, is to make very precise measurements of the Electric Dipole Moment (EDM) of electrons or muons. To do the next generation of EDM measurements will require advances in accelerator techniques and this award will focus on those advancements. Intellectual Merit Direct EDM searches using all-electric storage rings, with measurements of stored electrons, protons, or radioactive nuclei are being considered. Historically only a very small number of all-electric rings have been constructed and none at the scale envisioned for these dedicated EDM measurements. Thus, the research enabled here will provide essential insights into the feasibility of using larger-scale high-gradient electric field devices for these important measurements. The success of the EDM experimental procedure is strongly connected to the ability to create a suitably robust storage ring that can perform the desired functions necessary for successful spin precession measurements of intense beams at the accuracies required. Through this award, studies will be performed in pursuit of storage ring arrangements and parameter sets suitable for use in EDM measurements. For verification of results, comparisons will be made, where applicable, to beam conditions being created for a present-day EDM measurement of the muon system. This award will provide students of accelerator science the opportunity to engage with expert members of the field to acquire first-hand experience in the design and specification process for relevant storage ring systems for future EDM experiments, yielding a more experienced workforce upon exit from the university program. Broader Impacts Accelerator science will lead the way to future accelerators for virtually every branch of science and for a broad spectrum of applications to meet national needs, and collaboration between national laboratories and research universities is a natural approach to attract, train and educate a new generation of accelerator scientists and engineers. The learning curve for scientists to cross into the applied field of accelerator science is often long, and hence acquiring practical skill and knowledge as graduate students will provide a highly desired early-experience for future members of the much-needed workforce. The training and experiences enabled through this award will ultimately reach into many areas of research as the workforce expands into other technical disciplines.