8-12 July 2013
Fine structure of the Isoscalar Giant Quadrupole Resonance using proton inelastic scattering at 200 MeV in spherical to highly deformed neodymium isotopes
Presented by Dr. I. T. USMAN on 10 Jul 2013 from 14:10 to 14:30
Type: Oral Presentation
Track: Track B - Nuclear, Particle and Radiation Physics
Proton inelastic scattering measurements have been performed at iThemba Laboratory for Accelerator Based Sciences, using the state-of-the-art K600 Magnetic Spectrometer. This is one of the only two facilities in the world with a unique capability of high energy-resolution measurements at medium energies. The 200 MeV proton beams were delivered by the Separated Sector Cyclotron (SSC). As a result, fine structure has been observed in the region of the Isoscalar Giant Quadrupole Resonance (ISGQR) in five stable even-even neodymium (from spherical to highly deformed) target nuclei, namely, <sup>142</sup>Nd, <sup>144</sup>Nd, <sup>146</sup>Nd, <sup>148</sup>Nd and <sup>150</sup>Nd. Nuclei with mass number <i>A</i> ≈ 150 and neutron number <i>N</i> ≈ 90 are particularly of special interest since they occupy that region of the nuclide chart wherein the onset of permanent prolate deformation occurs. The stable even-even neodymium (<i>Z</i> = 60) isotopes have been chosen in the present study in order to investigate the influence of the onset of deformation on the excitation energy spectra in the ISGQR region (9 ≤ <i>E</i><sub>x</sub> ≤ 15 MeV), since they extend from the semi-magic <i>N</i> = 82 nucleus (<sup>142</sup>Nd) to the permanently deformed <i>N</i> = 90 (<sup>150</sup>Nd) nucleus. In order to enhance the ISGQR in the excitation energy spectra measured, a Discrete Wavelet Transform (DWT) background subtraction was carried out. A comparison of the resonance widths extracted shows a systematic broadening of the ISGQR, moving from spherical to highly deformed nuclei as has already been observed for the Isovector Giant Dipole Resonance (IVGDR) excited by &gamma-capture. Energy scales were extracted for the resonance region using the Continuous Wavelet Transform (CWT) technique. Another important further step which has been conducted is the extraction of 2<sup>+</sup> nuclear level densities from the fine structure in the region of the ISGQR. Experimental details, data extraction and analysis techniques, together with preliminary results will be presented.
Prof. John Carter John.Carter@wits.ac.za University of the Witwatersrand