High energy octupole resonance in 116Sn

The region of excitation energy from 7≤Ex≤38 MeV in 116Sn was studied with inelastic scattering of 240 MeV α particles. Parameters obtained for the isoscalar giant monopole resonance and the isoscalar giant quadrupole resonance are in agreement with accepted values. A peak exhausting (67±10)% of the E3 energy-weighted sum rule at Ex=21.8±0.5 MeV with width Γ=7.1±0.5 MeV was identified as the isoscalar high energy octupole resonance (HEOR). The energy and width are consistent with previous measurements made with proton, 3He, and α particle projectiles. The observed strength of the HEOR is in agreement with measurements made with 3He inelastic scattering, but is roughly three to four times larger than measurements made with α particle and proton inelastic scattering. copyright 1996 The American Physical Society