NSF Award
2205620
This award enables an exploration of future experiments for studying asymmetry between matter and antimatter. The prevalence of matter over antimatter is one of the most important unexplained observations in physics. As currently understood, the laws of physics obey symmetry properties that predict equality between the two forms of matter – at odds with our everyday experience as well as detailed astronomical observations. Such an inconsistency suggests that our current understanding of the laws of physics may be incomplete. ALPHA is an interdisciplinary antimatter experiment at CERN that tests this notion by producing antihydrogen and sensitively measuring its properties in comparison with the hydrogen atom. Trapping antimatter to produce antihydrogen is a plasma physics problem, consisting of collecting and manipulating large collections of charged particles using electric and magnetic fields. This project conducted in collaboration between the University of Michigan - Ann Arbor and Marquette University will advance understanding of novel plasma physics processes that occur in these experiments and develop protocols for possible future experiments. The project also supports development of interactive science exhibits for display at the Discovery World Science and Technology Center in Milwaukee, WI and at the Plasma Expo during the American Physical Society Division of Plasma Physics annual meetings.<br/><br/>Trapped antimatter is novel from a plasma physics perspective, as well as a particle physics perspective. These plasmas are so cold, and the magnetic fields of the trap are so strong, that they exist in a state that is not well described by the usual models of plasma physics. Specifically, the low temperature causes the plasma to be strongly coupled, which means that it behaves more like a supercritical fluid or a liquid, than the more common dilute-gas-like behavior. The strong applied magnetic field, in combination with the low density, also causes the plasma to be strongly magnetized. Currently understood methods of plasma theory do not apply in either of these circumstances. The research to be conducted will further develop recent theoretical approaches that extend plasma theory into these domains. The work will apply a newly developed kinetic theory and molecular dynamics simulations to advance understanding of three critical plasma-related processes: electron and positron compression, antiproton cooling, and mixing and recombination of antiprotons and positrons. Molecular dynamics simulations will be used to test the model development. The advanced models will be applied to explore more efficient ways to convert collections of positrons and antiprotons into antihydrogen atoms.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
