Strong-interaction effect measurements in sigma hyperonic atoms of W and Pb

Strong-interaction effects have been observed in the x-ray spectra of atoms formed with [Sigma][sup [minus]] hyperons in W and Pb. The spectra were analyzed for energy shifts and broadenings and for yield reductions of the final x-ray transitions before absorption of the [Sigma][sup [minus]] by the nucleus. The results for the 10[ital l][r arrow]9[ital k] transitions of [Sigma][sup [minus]] hyperonic atoms averaged over fine structure components are [sup 184]W: [var epsilon](9[ital k])=214[plus minus]60 eV, [Gamma](9[ital k])=18[plus minus]149 eV, [Gamma](10[ital l])=2[plus minus]2 eV; [sup 208]Pb: [var epsilon](9[ital k])=422[plus minus]56 eV, [Gamma](9[ital k])=428[plus minus]158 eV, [Gamma](10[ital l])=17[plus minus]3 eV, where the strong interaction shift [var epsilon]=[ital E][sub [ital m]][minus][ital E][sub [ital c]], [ital E][sub [ital m]] is the measured transition energy, and [ital E][sub [ital c]] is the transition energy calculated assuming no strong interaction and [Gamma] is the Lorentzian broadening. A four-parameter optical potential representing an effective spin-independent [Sigma][sup [minus]]-nuclear hadronic interaction was fitted by these results in combination with previous data from lower-[ital Z] nuclei.