Recent results from the decay studies of high-energy isoscalar giant resonances

The direct and statistical neutron decay of the isoscalar giant dipole resonance and a continuum region at higher excitation energy has been studied in Zr-90, Sn-116 and Pb-208 using the (alpha, alpha'n) reaction at a bombarding energy of 200 MeV. The spectra of fast decay neutrons populating valence neutron-hole states were analyzed, and estimates for the branching ratios were determined to compare to recent theoretical predictions. The observation of the direct nucleon decay channels helped to separate giant resonance strengths and suppress the underlying background and continuum, which lead to an indication for the existence of the first overtone mode of the isoscalar giant quadrupole resonance.