Alpha Decay of the Giant Quadrupole Resonance inU238

Evidence for the $\alpha$ decay of the giant quadrupole resonance is reported. Measurements of the reaction ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}(e, e^{\prime }, \alpha ){}_{}{}^{234}{}_{}{}^{}\mathrm{Th}$ in the region 9-24 MeV are presented. The results imply that the reaction goes dominantly through $E2\mathrm{}$ absorption. The amount of $E2\mathrm{}$ strength used by the $\alpha$ emission channel exhausts 50% of the isoscalar energy-weighted sum rule.