  The differential cross section for the $^{12}$C$(\gamma,\pi^{+}p)$ reaction
has been measured in the $\Delta$(1232) resonance region at high recoil momenta
of the residual nuclear system. The data are analyzed under the assumption that
the formation of the $\pi^+p$ pairs may be interpreted as a
$\gamma\Delta^{++}\to\pi^+p$ process which takes place on a $\Delta^{++}$
preexisting in the target nucleus. Estimates of the $\Delta^{++}$ momentum
distribution $\rho_{\Delta^{++}}(\bar{p})$=0.17 fm$^3$ for a mean momentum
$\bar{p}=300\pm49$ MeV/c as well as the number of $\Delta$ isobars per nucleon
$N_\Delta=0.017$ were obtained for $^{12}$C.
