Direct Measurement of the Hyperfine Structure Interval of Positronium Using High-Power Millimeter Wave Technology

In this thesis, the author develops new high-power millimeter wave techniques for measuring the hyperfine structure of positronium (Ps-HFS) directly for the first time in the world. Indirect measurement of Ps-HFS in the literature might have systematic uncertainties related to the use of a static magnetic field. Development of the millimeter wave devices supports the precise determination of Ps-HFS by directly measuring the Breit-Wigner resonant transition from o-Ps to p-Ps without the magnetic field. At the same time, the width of the measured Breit-Wigner resonance directly provides the lifetime of p-Ps. This measurement is the first precise spectroscopic experiment involving the magnetic dipole transition and high-power millimeter waves. The development of a gyrotron and a Fabry-Pérot cavity is described as providing an effective power of over 20 kW, which is required to cause the direct transition from o-Ps to p-Ps. Those values measured by the newly developed millimeter wave device pave the way for examining the discrepancy observed between conventional indirect experiments on Ps-HFS and the theoretical predictions of Quantum Electrodynamics.

Nominated as an outstanding contribution by the University of Tokyo's Physics Department in 2013 Describes first direct determination of the hyperfine interval of ground-state positronium and the lifetime of para-positronium Introduces development of new millimeter wave devices, such as a long-time stable gyrotron with frequency tunability and a Fabry-Pérot cavity of high finesse Explains precise measurement by a new millimeter wave device for measuring Ps-HFS Includes supplementary material: sn.pub/extras

Autorentext
Dr. Akira Miyazaki
Department of Physics, The University of Tokyo
miyazaki@icepp.s.u-tokyo.ac.jp

Inhalt
Introduction.- Experiment.- Analysis.- Discussion.- Conclusion.