Widths of Analog States in Bi and Po from (p,n) Spectra

Isobaric analog states have been observed in the neutron spectra of ($p,n$) reactions on targets of ${}_{}{}^{206}{}_{}{}^{}\mathrm{Pb}$, ${}_{}{}^{207}{}_{}{}^{}\mathrm{Pb}$, ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$, and ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}$. After removal of instrumental resolution effects, the natural widths are, respectively, 196 ± 26, 203 ± 32, 202 ± 34, and 151 ± 34 keV. Except in the ${}_{}{}^{206}{}_{}{}^{}\mathrm{Pb}$ case, these widths are substantially smaller than those observed in $\overline{p}$ spectra from ($p,n\overline{p}$) experiments on the same target nuclei but are in agreement with ($p,p^{\prime }$) resonance results in the two cases that have been measured.