ENERGY SHARING IN THE DEEXCITATION OF THE RU-90 COMPOUND NUCLEUS VIA THE P-ALPHA-CHANNEL

Using the 4 pi light charged-particle detector DIAMANT in combination with the gamma-ray spectrometer EUROGAM II, the decay of the Ru-90 com pound nucleus via the p alpha channel was studied. These nuclei were p roduced at an excitation energy of 54.9 MeV and with a maximum angular momentum of 37 (h) over bar by the 120 MeV S-32 + Ni-58 reaction. The measurement of the energy of the two particles allowed the determinat ion of the energy distribution of the entry states. A particular behav ior of the sharing of the available energy between the two particles w as found: For increasing values of the entry-state energy, the mean en ergy for protons remains almost constant while for alpha panicles it d ecreases. This behavior is well reproduced by the evaporation code LIL ITA_N95. The physics underlying the decay is discussed in the framewor k of the statistical model which predicts a strong correlation between the excitation energy and the angular momentum of the evaporation res idue. This result encourages the use of the p alpha channel to select the excitation energy and the angular momentum of the evaporation resi due for superdeformed band studies.