Strong interaction and mass measurements using antiprotonic atoms

Abstract

X-ray transition energies of antiprotonic atoms formed in targets of $^{6}\mathrm{Li}$, $^{7}\mathrm{Li}$, C, Si, P, Fe, Y, Zr, Cs, and Yb have been measured. Level shifts and widths due to the strong interaction were determined. A phenomenological fit to the data using an optical-model potential proportional to the nuclear matter density and to an effective $\overline{p}$-nucleus $s$-wave scattering length yielded [$(0.85\ifmmode\pm\else\textpm\fi{}0.38)+i(2.66\ifmmode\pm\else\textpm\fi{}0.28)$] fm for the effective scattering length. In addition, the mass of the antiproton was determined to be 938.229 \ifmmode\pm\else\textpm\fi{} 0.049 MeV from the observed energies of the $\overline{p}$ x-ray transitions unperturbed by the strong interaction.NUCLEAR REACTIONS, hadronic atoms. Measured antiprotonic atom x-ray transition energies; determined strong interaction shifts and widths; deduced effective scattering length; deduced antiproton mass.