Level density and γ-ray strength in 27,28 Si

Am ethod to extract simultaneously level densities and γ -ray transmission coefficients has for the first time been tested on light nuclei utilizing the 28 Si( 3 He,αγ ) 27 Si and 28 Si( 3 He, 3 He � γ) 28 Si reactions. The extracted level densities for 27 Si and 28 Si are consistent with the level densities obtained by counting known levels in the respective nuclei. The extracted γ -ray strength in 28 Si agrees well with the known γ -decay properties of this nucleus. Typical nuclear temperatures are found to be T ∼ 2. 4M eV at around 7 MeV excitation energy. The entropy gap between nuclei with mass number A and A ± 1 is measured to be δS ∼ 1.0kB ,w hich indicates an energy spacing between single-particle orbitals comparable with typical nuclear temperatures.