Level densities for the ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ system are calculated within a $4\hslash \omega$ model space by utilizing a realistic nucleon-nucleon interaction. The fluctuations are smoothed with a least squares fitting procedure and exponential fits of the form $A \exp \left(\frac{E}{T}\right)$ are calculated for the density and total number of levels. The total number of levels is also compared with the predictions of the equidistant model. Systematics of level densities for even-even nuclei for $4\le A\le 66$ and for nuclei in general for $4\le A\le 240$ are discussed.

NUCLEAR STRUCTURE ${}_{}{}^4{}_{}{}^{}\mathrm{He}$, calculated $J^{\pi }=0^{+}, 0^{-}, 1^{+}, 1^{-}, 2^{+}, 2^{-}, 3^{+}, 3^{-}, 4^{+}, 4^{-}, 5^{+}, 5^{-}, \mathrm{and} 6^{+}$ levels up to 85 MeV excitation energy. Level density parameters are obtained for constant temperature and equidistant models.

• Received 9 August 1978

DOI:https://doi.org/10.1103/PhysRevC.19.2050