Observation of a Double Isobaric Analog State in the ReactionBi209(π+e,π−)At209

Abstract

Pion double charge exchange has been used to populate the double isobaric analog state in ${}_{}{}^{209}{}_{}{}^{}\mathrm{At}$ with use of the neutron-rich target ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}$. The data were obtained at an energy of 292 MeV and at an angle of 5°, as the double-charge-exchange reaction mechanism has been shown to be dominated by analog transitions under these conditions in previous work on light nuclei. The measured cross section is found to be in good agreement with semiclassical predictions by Johnson.