A study of the decay modes of the $\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}\text{and}\text{i}{}_{\mathrm{<mtext>11</mtext><mtext>2</mtext>}}$ isobaric analog resonances in ²⁰⁹Bi using electrons and bremsstrahlung

Abstract

Differential cross sections at several scattering angles and proton spectra around the $\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ spin-flip and $\text{i}{}_{\mathrm{<mtext>11</mtext><mtext>2</mtext>}}$ non-spin-flip IAR in ²⁰⁹Bi were measured with the (e, p) reaction using a broad-range magnetic spectrometer and 100 solid-state detectors. Experiments on the (γ, p) reaction using bremsstrahlung were also performed on the same subjects using the same detector system and geometry as for the (e, p) reaction experiments. Both data agree well with each other when the virtual photon theory is used. Strengths deduced for the resonance at the $\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ IAS at θ^lab = 125.3° are in basic agreement with previous data which are in contradiction with the results of the (p, γ₀) reaction and β-decay. Proton decay modes of these resonances were deduced by the photondifference method. Proton groups emitted through the $\text{i}{}_{\mathrm{<mtext>11</mtext><mtext>2</mtext>}}$ IAR are found to have a decay mode typical of the IAS and leave the residual nucleus in neutron l p-1 h states. The decay mode at the $\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ IAR shows an anomalous reaction process as do previous data on the $\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$ spin-flip IAR in ¹³⁹La.