The energy and angular distribution of the $\alpha$ particles from the ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}(\mathrm{n},\alpha )$ and ${}_{}{}^{60}{}_{}{}^{}\mathrm{Ni}(\mathrm{n},\alpha )$ reactions for 14.1 MeV incident neutron energy were measured by means of a multitelescope system. The results concerning the total He-production cross sections and the angle-integrated $\alpha$-emission cross sections $\frac{d\sigma }{d{E}_{\alpha }}$ are in fair agreement with previous measurements; for the angular distribution no detailed measurements have as yet been reported. The results are analyzed in the framework of the statistical model of nuclear reactions. Comparison of such calculations with the measured $\alpha$-emission cross sections allows one to extract nuclear level densities for ${}_{}{}^{53}{}_{}{}^{}\mathrm{Cr}$ and ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$, the residual nuclei reached in the studied reactions in the energy region up to the neutron binding energy, and for ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ and ${}_{}{}^{60}{}_{}{}^{}\mathrm{Ni}$, the residual nuclei reached by neutron emission for energies around 11 MeV. Within experimental error a purely exponential increase of the level density with excitation energy was found for both ${}_{}{}^{53}{}_{}{}^{}\mathrm{Cr}$ and ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$. The spin cutoff parameters for ${}_{}{}^{53}{}_{}{}^{}\mathrm{Cr}$ and ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$ derived from the data indicate that there is no reduction of the effective moment of inertia below the rigid body value.

• Received 9 March 1984

DOI:https://doi.org/10.1103/PhysRevC.30.72