Decay modes of the isocsalar giant quadrupole resonance in /sup 58/Ni

Particle decay modes of the giant quadrupole resonance in /sup 58/Ni have been determined in a particle-particle angular correlation experiment. The branching ratios are (59 +- 12) % and (12 +- 4) % ((30 +- 6) % and (6 +- 2) % of the isoscalar E2 energy-weighted sum-rule strength) for proton and ..cap alpha..-particle decay, respectively, and are very similar to those of the underlying continuum and the statistical-model predictions. Our results disagree with a recent electroproduction singles experiment.