Eur. Phys. J. A (2018) 54: 234
https://doi.org/10.1140/epja/i2018-12664-5

Regular Article - Experimental Physics

Studies of the Giant Dipole Resonance in ²⁷Al , ⁴⁰Ca , ⁵⁶Fe , ⁵⁸Ni and ²⁰⁸Pb with high energy-resolution inelastic proton scattering under 0°

¹ School of Physics, University of the Witwatersrand, 2050, Johannesburg, South Africa
² Department of Orthopaedic Surgery, University of the Witwatersrand, 2193, Johannesburg, South Africa
³ Department of Subatomic Physics, iThemba LABS, PO Box 722, 7129, Somerset West, South Africa
⁴ School of Earth Sciences, University of the Witwatersrand, 2050, Johannesburg, South Africa
⁵ Department of Physics, University of Cape Town, 7700, Rondebosch, South Africa
⁶ Institut für Kernphysik, Technische Universität Darmstadt, D-64289, Darmstadt, Germany
⁷ Department of Physics, University of Stellenbosch, 7602, Matieland, South Africa
⁸ Research Center for Nuclear Physics, Osaka University, 567-0047, Ibaraki, Osaka, Japan

^* e-mail: vnc@ikp.tu-darmstadt.de

Received: 31 July 2018
Accepted: 29 November 2018
Published online: 31 December 2018

Abstract

A survey of the fine structure of the Isovector Giant Dipole Resonance (IVGDR) was performed, using the recently commissioned Zero-degree Facility of the K600 magnetic spectrometer at iThemba LABS. Inelastic proton scattering at an incident energy of 200MeV was measured on ²⁷Al , ⁴⁰Ca , ⁵⁶Fe , ⁵⁸Ni and ²⁰⁸Pb . A high energy-resolution ( keV FWHM) could be achieved after utilising faint-beam and dispersion-matching techniques. A considerable fine structure is observed in the energy region of the IVGDR and characteristic energy scales are extracted from the experimental data by means of a wavelet analysis. The comparison with Quasiparticle-Phonon Model (QPM) calculations provides insight into the relevance of different giant resonance decay mechanisms. Photoabsorption cross sections derived from the data assuming a dominance of relativistic Coulomb excitation are in fair agreement with previous work using real photons.