SAIP 2011

Fine Structure of the Isovector Giant Dipole Resonance: a survey with (p,p') scattering at zero degrees

15 Jul 2011, 08:30

15m

Acro8

Oral Presentation Track B - Nuclear, Particle and Radiation Physics NPRP

Speaker

Mr Maxwell Jingo (University of the Witwatersrand, South Africa)

Description

A survey of the fine structure phenomenon of the Isovector Giant Dipole Resonance (IVGDR) was investigated, using the newly commissioned Zero-degree Facility of the K = 600 magnetic spectrometer of iThemba LABS. Measurements were performed for inelastic proton scattering at an incident energy of 200 MeV for targets ranging from ²⁷Al to ²⁰⁸Pb. Targets of areal density of 1 – 2 mg/cm² gave an energy resolution of 45 keV Full Width at Half Maximum (FWHM) after utilising the faint-beam dispersion-matching technique. A reasonable background subtraction procedure allowed for the extraction of excitation energy spectra with low background. The data from the survey promise to give a unique insight into the competition of the various damping mechanisms contributing to the decay of the IVGDR. Furthermore, level densities of J^π = 1^– states can be extracted in a model-independent way, which serves as an important input to models applied in astrophysics. Finally, this survey will simultaneously provide bench-marks on the capabilities and limitations of the new Zero-degree Facility important for planning of the future experimental work. The experimental techniques, experimental results and preliminary theoretical calculations for the measurement of 0^o proton scattering will be presented.