Photoemission of Two Nucleons fromBe9in theΔ(1232)Resonance Region

Coincidence measurements of two nucleons from the reactions ${}_{}{}^9{}_{}{}^{}\mathrm{Be}(\gamma ,pn)X$ and ${}_{}{}^9{}_{}{}^{}\mathrm{Be}(\gamma ,pp)X$ have been made in the $\Delta \mathrm{}\left(1232\right)\mathrm{}$ resonance region with a tagged-photon beam. From the momentum and angular correlations between the two nucleons, two quasifree reactions, $\gamma +{}_{}{}^{\prime \prime }{}_{}{}^{}p{n}^{\prime \prime }\to p+n$ and $\gamma +{}_{}{}^{\prime \prime }{}_{}{}^{}p{p}^{\prime \prime }\to p+p$, are clearly identified. The separation energy and the momentum distribution of the quasifree deuteron in ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$ are determined together with the ratio between cross sections of the two quasifree reactions.