Fine structure of the isovector giant dipole resonance in Nd142–150 and Sm152
| Autor: | Y. Fujita, Gordon R. J. Cooper, Norbert Pietralla, C. O. Kureba, J. W. Brümmer, W. Kleinig, E. Z. Buthelezi, A. V. Sushkov, M. B. Latif, J. Carter, Elias Sideras-Haddad, J. P. Mira, B. Rebeiro, L. M. Donaldson, Carlos A. Bertulani, P. von Neumann-Cosel, L. Pellegri, J. Kvasil, R. W. Fearick, K. C. W. Li, S. V. Förtsch, P. Papka, M. Jingo, F. Nemulodi, I. T. Usman, G.F. Steyn, Achim Richter, P. Adsley, R. Neveling, Atsushi Tamii, N. Y. Kheswa, N. Yu. Shirikova, F. D. Smit, V. Yu. Ponomarev, Hisanori Fujita, V. O. Nesterenko, J. A. Swartz, Paul-Gerhard Reinhard |
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| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | Physical Review C. 102 |
| ISSN: | 2469-9993 2469-9985 |
| DOI: | 10.1103/physrevc.102.064327 |
| Popis: | Background: Inelastic proton scattering at energies of a few hundred MeV and very-forward angles including $0^\circ$ has been established as a tool to study electric-dipole strength distributions in nuclei. The present work reports a systematic investigation of the chain of stable even-mass Nd isotopes representing a transition from spherical to quadrupole-deformed nuclei. Purpose: Extraction of the equivalent photo-absorption cross sections and analysis of their fine structure in the energy region of the IsoVector Giant Dipole Resonance (IVGDR). Method: Proton inelastic scattering reactions of 200 MeV protons were measured at iThemba LABS in Cape Town, South Africa. The scattering products were momentum-analysed by the K600 magnetic spectrometer positioned at $\theta_{\mathrm{Lab}}=0^\circ$. Using dispersion-matching techniques, energy resolutions of $\Delta E \approx 40 - 50$ keV were obtained. After subtraction of background and contributions from other multipoles, the spectra were converted to photo-absorption cross sections using the equivalent virtual-photon method. Results: Wavelet-analysis techniques are used to extract characteristic energy scales of the fine structure of the IVGDR from the experimental data. Comparisons with the Quasiparticle-Phonon Model (QPM) and Skyrme Separable Random Phase Approximation (SSRPA) predictions provide insight into the role of different giant resonance damping mechanisms. Conclusions: Fine structure is observed even for the most deformed nuclei studied. Fragmentation of the one particle-one hole ($1p1h$) strength seems to be the main source of fine structure in both spherical and deformed nuclei. Some impact of the spreading due to coupling of the two particle-two hole ($2p2h$) states to the $1p1h$ doorway states is seen in the spherical/transitional nuclei, where calculations beyond the $1p1h$ level are available. |
| Databáze: | OpenAIRE |
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