Isobaric analogue resonance studies in some rare-earth nuclei

Abstract

The theme of the work is a study of isobaric analogue reson ances in heavy nuclei of the rare-earth region. After an introductory chapter describing the physical concepts associated with the analogue resonance phenomenon, the thesis is divided into two parts: part A which describes cross-section measurements of analogue resonances in elastic and inelastic proton scattering and part B which covers beam optics calculations which were performed in preparation for the use of the ANU polarised ion source for further analogue resonance studies. Unfortunately, experimental difficulties with the source have prevented any polarisation measurements through analogue resonances being carried out.

Spreading widths of isobaric analog states and the isovector giant monopole resonance

“…Mainly even-A nuclei are reached in these reactions. Excitation functions for resonance reactions 15,16,18,[26][27][28][29][30][31][32][33][34][35] such as elastic or inelastic proton scattering via the IAS as well as one-nucleon pickup 12) or stripping 36) have also been used to study IAS. Mainly odd-A nuclei are reached in these reactions.…”

“…Such an adjustment reverses almost quantitatively the adjustment of eqs. (33) and (35) introduced phenomenologically by Lane and Mekjian 9). Alternately, if a = 1 is assumed (cases 23 to 25), the parameters which describe the second moment M2 and hence the width F~vM(EwM) lead to values which are a factor of about 0.65 smaller (for/3 ---0) than those introduced by MacDonald and Birse lo).…”

Isobaric analog states in rare-earth nuclei studied with the (3He, t) charge-exchange reaction at θL = 0°

“…It was the objective of the present work to measure Coulomb displacement energies of deformed nuclei with the highest possible precision in order to establish the effect of the hexadecapole deformation of the nuclear shape. It was in part stimulated by the results of Merril et al 15) who observed an unexplained weak local maximum within the deformation minimum. It occurs near the region where //, is known to change sign.…”

“…15) that the direct Coulomb energy of deformed nuclei is reduced by the approximate factor 1-fl~/4~z where //2 is the quadrupole deformation parameter. Indeed, reductions with respect to estimates for spherical nuclei of up to 150 keV have been observed experimentally but quantitative analyses are scarce [14][15][16]. The influence of the hexadecapole deformation f14 has never been established.…”