Light charged particle emission in the matched reactions 280 MeV {sup 40}Ar+{sup 27}Al and 670 MeV {sup 55}Mn+{sup 12}C: Inclusive studies

In order to test the statistical model's ability to predict the behavior of relatively light mass systems (A{approx_equal}67) with large angular momenta, two matched heavy ion nuclear reactions were used to produce {sup 67}Ga{sup *} composite nuclei at an excitation energy of 127 MeV. Light charged particles (protons, deuterons, tritons, and {alpha} particles) were used as probes to characterize the composite systems and track the deexcitation processes. >From these measurements, energy spectra, cross sections, angular distributions, anisotropy ratios, and particle multiplicities were deduced. Measuring many degrees of freedom provides a stringent test for the statistical models. What is found is that models which did well in predicting the behavior of heavy composite systems (A{approx_equal}150), are unable to simultaneously reproduce energy spectra, angular distributions, and particle multiplicities for the lighter systems (A{approx_equal}67), where angular momentum plays a dominant role. This implies that more rigorous models and/or additional physics are needed to understand the behavior of the hot, high-spin nuclear matter in this mass region. (c) 1999 The American Physical Society.