Electroexcitation ofLi6with application to the reactionsLi6(π−,γ)1sHe6(0+,2+)

The transverse form factor for the 5.37 MeV($2^{+}$,$T=1\mathrm{}$) level of ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ is analyzed in terms of a phenomenological model to give the configuration amplitudes and transition density. Radiative pion capture rates for the $1s$ atomic orbital of ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ leading to the two lowest states of ${}_{}{}^6{}_{}{}^{}\mathrm{He}$ are estimated using the phenomenological functions. The radiative pion capture rate to ${}_{}{}^6{}_{}{}^{}\mathrm{He}$(g.s.) agrees with experiment, but the rate to ${}_{}{}^6{}_{}{}^{}\mathrm{He}$($2^{+}$,1.8 MeV) is larger than the measured value. It is shown that if the longitudinal form factor is small at $q\approx m_{\pi }$, the transverse 5.37 MeV form factor gives the radiative pion capture matrix elements directly. As part of this study, the $C2\mathrm{}$ form factor was measured near $q=m_{\pi }$, and its implications on the wave functions are considered.