Resonance Neutron Capture in Rh103

The $\ensuremath{\gamma}$-ray spectra following slow-neutron capture in a target of ${\mathrm{Rh}}^{103}$ have been measured with the fast-chopper time-of-flight facility at the high flux beam reactor at Brookhaven National Laboratory. A total of 145 radiative intensities, involving transitions from seven resonances and 16 unresolved resonances, to levels in ${\mathrm{Rh}}^{104}$ have been recorded. A neutron binding energy of 6999.3\ifmmode\pm\else\textpm\fi{}1.5 keV is obtained. From these high-energy $\ensuremath{\gamma}$-ray data, several spin assignments for levels in ${\mathrm{Rh}}^{104}$ are made. The distribution of transition probabilities in rhodium is not consistent with the Porter-Thomas distribution; values of $\ensuremath{\nu}={2.70}_{\ensuremath{-}0.40}^{+0.53}$ and $\ensuremath{\nu}={2.45}_{\ensuremath{-}0.40}^{+0.38}$ are obtained as best fits to the class of ${\ensuremath{\chi}}^{2}$ distribution functions to spin-0 and spin-1 resonances, respectively. The gross shape of the $\ensuremath{\gamma}$-ray spectrum shows an enhancement of strength to states near 1 MeV in excitation energy, both for thermal and resonance capture. It is shown that this enhancement is not due to a direct-reaction process, and it is suggested that the presence of doorway states may be responsible for this enhancement.