Excitation of low-lying levels and giant resonances in 90Zr via 57.5 MeV polarized proton inelastic scattering

doi:10.1016/0375-9474(79)90612-2

Nuclear Physics A

Volume 315, Issue 3, 5 March 1979, Pages 291-309

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Abstract

Differential cross section and analyzing power angular distributions have been measured for transitions to low-lying bound states with J^π = 2⁺, 3⁻, 4⁺ and 5⁻, and the giant resonance region from 6 to 27 MeV excitation energy. Collective model calculations using a full Thomas form factor reproduce the data fairly well. The so-called LEOR turns out not to be seen as pure E3 in (p, p′). In the giant resonance region the data do not reveal the presence of a sizeable monopole strength, 10–20% of the energy-weighted sum rule at most. There is strong indication for a mixture of E2 (18% of the EWSR) and E4 (16% of the EWSR). Calculations were also carried out using RPA (1p1h) wave functions. They reproduce the experimental data rather poorly, except for the general behaviour of the cross-section angular distributions.

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Experimental data for all nuclei with mass number A = 90 have been evaluated, and their corresponding level schemes from radioactive decay and reaction studies are presented.
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Cutoff Date:All data received by May 1, 1997 were evaluated.
General Policies and Organization of Material:See the January issue of Nuclear Data Sheets.
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1996, Nuclear Physics A
We show that pre-equilibrium inelastic scattering reactions to the continuum contain substantial collective components in addition to the multistep direct and multistep compound reactions. These collective cross-sections are calculated using the experimental data for low-lying collective excitations supplemented where necessary by the giant multipole resonances evaluated using the energy-weighted sum rule. The MSC and MSD cross-sections are evaluated by the Feshbach-Kerman-Koonin theory using a consistent set of parameters determined by analyses of (p, n) reactions, that have practically no collective components. The results are compared with high-resolution neutron inelastic scattering data and prove able to account for the absolute magnitude of the cross-sections and also their detailed structure.
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Nuclear Physics A

Abstract

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Nuclear data sheets for A = 90

A new multistep direct reaction mechanism: Collective excitations in the continuum

Nuclear data sheets for A = 90

Hexadecapole component in the giant quadrupole resonance region of <sup>208</sup>Pb

Hexadecapole strength in the region of the low-energy octupole resonance in <sup>90</sup>Zr

Analyzing powers of the continuum spectra: 65 MeV polarized protons on <sup>12</sup>C, <sup>28</sup>Si, <sup>45</sup>Sc, <sup>58</sup>Ni, <sup>93</sup>Nb, <sup>165</sup>Ho, <sup>166</sup>Er and <sup>209</sup>Bi