Escape width of the giant monopole resonance in90Zr

The proton and neutron decay of the giant monopole resonance in {sup 90}Zr is analyzed in terms of collective and statistical doorway states. For this purpose the hybrid model of the decay is used in the context of channel particle competition. The semidirect components are compatible with the particle-hole continuum random-phase-approximation calculations. The protons spectra are found to be predominantly statistical while the neutron spectra contain semidirect contributions. {copyright} {ital 1997} {ital The American Physical Society}