Grant: Discovery Grants Program - Individual

Antihydrogen: The simplest antimatter atom consists of a positron (antielectron) orbiting an antiproton. It is our aim (in the context of the ATRAP collaboration led by G. Gabrielse of Harvard) to study these antimatter atoms and to determine if the properties of antihydrogen exactly mirror the properties of regular hydrogen. We have already been able to produce slow antihydrogen atoms at the CERN laboratory in Geneva using two different processes, including a dual-charge-exchange process developed at York. Our next step is to suspend them in a magnetic trap. We have made major steps towards these goals over the past five years, and expect that we will be able to trap and study antihydrogen atoms soon. Positronic Atoms: An exotic atom constructed of one proton, two electrons and one positron will be studied. We intend to create highly-excited (Rydberg) states of this positronic atom. The creation processes for these states is similar to the processes used for creating antihydrogen, and thus we will be able to study these processes in our laboratory at York, without need for the CERN laboratory. We also will use these exotic atoms to make very precise studies of the properties of the hydrogen minus ion and other negative ions. Helium Fine Structure: We continue to make very-high-precision microwave measurements of the fine structure of helium in order to test quantum electrodynamics in this two-electron atom and to make a measurement of the fine-structure constant--the constant that determines the strength of all electromagnetic interactions. Our latest measurements use the Ramsey technique of separated oscillatory fields to achieve higher precision. In addition, a new series of measurement in the lighter helium-3 isotope will be made and used to shed light on the current discrepancy between theory and experiment for these intervals.