K- mass from kaonic atoms

The energies of the six circular transitions (n=13→n=12 through n=8→n=7) of the K-Pb exotic atom have been measured to high precision (typically approximately 50 ppm) using Ge(Li) spectrometers. The data acquisition system was computer controlled and stabilized, the energy calibration spectrum was taken simultaneously with the data spectrum. The experimental energies of the six transitions were corrected for ADC nonlinearities and data-calibration spectrum shifts, as well as the presence of unresolved noncircular transition contaminants. The energies of five of the transitions (13→12 through 9→8) were computed from quantum electrodynamics, including all significant orders of vacuum polarization, electron screening and nuclear polarization. The mass of the K- was adjusted to achieve a best fit with the experimental energies: the result was msub(K-)=493.657+-0.020 MeV. (Auth.)