Probing theΔNNcomponent of3He

The ${}^3\mathrm{He}(\gamma ,{\pi }^{\pm }p)$ reactions were measured simultaneously over a tagged photon energy range of $800<~E_{\gamma }<~1120$ MeV, well above the $\Delta$ resonance region. An analysis was performed to kinematically isolate $\Delta$ knockout events from conventional $\Delta$ photoproduction events, and a statistically significant excess of ${\pi }^{+}p$ events was identified, consistent with ${\Delta }^{++}$ knockout. Two methods were used to estimate the $\Delta \mathrm{NN}$ probability in the ${}^3\mathrm{He}$ ground state corresponding to the observed knockout cross section. The first gave a lower probability limit of $1.5\pm 0.6\pm 0.5\%;$ the second yielded an upper limit of about $2.6\%.$