Systematics of the isoscalar giant monopole resonance from 60 MeV inelastic proton scattering

Evidence for an isoscalar giant monopole resonance is provided for seven nuclei with A ~ 58. The resonance excitationenergy is ~- 80 × A-1/3 MeV. For nuclei with A ~ 90, nearly 100% of the L = 0, T = 0 energy-weighted sum rule is depletedin the resonance, in agreement with earlier work on 2°spb and 144Sm. Only ~ 30% is found in SSNi, and no clear evidenceis found for localized monopole strength in 4°Ca.