Giant resonances are highly collective modes of nuclear vibration. These modes, unlike many excited states with lower excitation energy, involve the participation of a large fraction of the nucleons within a nucleus. While there are many types of giant resonances, the group is primarily focused on the electric and isoscalar modes, which correspond to all protons and neutrons vibrating in phase with one another.
The giant resonances, being collective phenomena, are influenced by and thus constrain properties of bulk nuclear matter. The “breathing” mode, the isoscalar giant monopole resonance (ISGMR), is a compressional mode and allows for a direct experimental constraint on the nuclear incompressibility. To measure these modes, the group uses deep inelastic alpha scattering at 100 MeV/u off of stable nuclei, from which the angular distributions can be used to isolate and extract the distribution of strength of the resonances. These experiments are conducted at the Research Center for Nuclear Physics at Osaka University.
- K.B. Howard, U. Garg, et al. Compression-mode resonances in the calcium isotopes and implications for the asymmetry term in nuclear incompressibility. doi: 10.1016/j.physletb.2019.135185.
- K.B. Howard, U. Garg, et al. Where we stand on structure dependence of ISGMR in the Zr-Mo region: Implications on K∞. doi: 10.1140/epja/i2019-12762-x.
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