Deformation effects on isoscalar giant resonances in Mg 24

Strength distributions for isoscalar giant resonances with multipolarity L <= 2 have been determined in Mg-24 from "instrumental background-free" inelastic scattering of 386-MeV alpha particles at extreme forward angles, including 0 degrees. The isoscalar E0, E1, and E2 strengths are observed to be 57 +/- 7%, 111.1(-7.2)(+10.9)%, and 148.6 +/- 7.3%, respectively, of their energy-weighted sum rules in the excitation energy range of 6 to 35 MeV. The isoscalar giant monopole (ISGMR) and quadrupole (ISGQR) resonances exhibit a prominent K splitting which is consistent with microscopic theory for a prolate-deformed ground state of Mg-24. For the ISGQR it is due to splitting of the three K components, whereas for the ISGMR it is due to its coupling to the K = 0 component of the ISGQR. Deformation effects on the isoscalar giant dipole resonance are less pronounced, however.