Compound nuclear lifetimes at high excitation energies via a new statistical fluctuation method

A new method to determine compound nuclear lifetimes at high excitation energies is proposed and applied to the system 12C(28Si, α)36Ar at two different bombarding energies, 190 and 277 MeV. The alpha particle spectra show a structure which directly reflects the fluctuating behavior of the first de-excitation step. Coherence widths and thus lifetimes for the nucleus 36Ar were obtained via a correlation function analysis. The results at low excitation energies are consistent with standard statistical models while the result at high excitation energy is compatible with a theoretically predicted change of the level density parameter.