Giant Resonances in 44Ca, 54Fe, 64Zn, 68Zn, and 94Mo
Abstract
The centroids of the Giant Monopole Resonance (GMR) exhibit significant scattering about an expected A^-1/3 mass dependence. Also, the GMR strength distribution had been observed to transition in shape from symmetric (Gaussian-like) in heavier nuclei to asymmetric over the 40<A<90 region. The origin of this is not clear and may be the result of nuclear structure or some other effect. This suggested a study of the GMR in 44Ca, 54Fe, 64Zn, and 68Zn. In the A~90 region for Zr and Mo, a second unexplained peak can be seen in the strength distribution for the GMR. Analysis of the GMR in 94Mo may help to explain this characteristic.
Isoscalar giant resonances in 44Ca, 54Fe, 64Zn, 68Zn, and 94Mo have been studied with inelastic scattering of 240 MeV α particles at small angles including 0°. In 44Ca, a majority of the Energy Weighted Sum Rule (EWSR) was identified for E0 and E2 (≈70%), and nearly half was identified for E1. Between 70 and 105% of the expected isoscalar E0 strength has been identified below Ex = 40 MeV for 54Fe, 64Zn, and 68Zn. Between 70 and 104% of the E1 strength has been identified while 60% of E2 strength in 54Fe and 68Zn and 120% of the strength in 64Zn has been identified. For 94Mo all of the expected EWSR for the isoscalar E0 resonance was found (104%). A significant portion of the EWSR was found for the isoscalar E1 (75%), E2 (61%), and the high energy octupole E3 (46%) resonances.
Citation
Button, Jonathan Thomas (2016). Giant Resonances in 44Ca, 54Fe, 64Zn, 68Zn, and 94Mo. Doctoral dissertation, Texas A & M University. Available electronically from https : / /hdl .handle .net /1969 .1 /157115.