Level densities and radiative strength functions

• Main Authors: Siem, S., Buerger, A., Guttormsen, M., Larsen, A. C., Nyhus, H. T., Rekstad, J., Syed, N. U. H., Toft, H. K., Tveten, G. M., Agvaanluvsan, U., Mitchell, G., Chankova, R., Triangle Universities Nuclear Laboratory, Durham, NC 27708, Schiller, A., Voinov, A.
• Format: Conference Proceeding
• Language: English
• Subjects: DYSPROSIUM ISOTOPES; ENERGY-LEVEL DENSITY; GAMMA SPECTRA; IRON ISOTOPES; MEV RANGE 01-10; MOLYBDENUM 96; NEUTRON REACTIONS; NUCLEAR PHYSICS AND RADIATION PHYSICS; OSLO CYCLOTRON; RADIANT HEAT TRANSFER; RARE EARTH NUCLEI; SCANDIUM ISOTOPES; STRENGTH FUNCTIONS; TIN 116; TIN 117; VANADIUM ISOTOPES
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/1.3087125

This paper presents a summary of the latest results from experiments performed at the Oslo Cyclotron. The Oslo group has developed a technique to extract simultaneously the level density and radiative strength function from primary {gamma}-ray spectra. A small (pygmy) resonance in the radiative strength function has been observed at around 3 MeV in several deformed rare earth nuclei. This resonance is shown to be of M1 character and the origin is thought to be the scissors mode. This resonance vanishes for the spherical Sm nuclei, as expected, since the scissors mode is dependent on deformation. Experiments performed in Oslo found the resonance in Dy isotopes to be twice as wide as the width extracted in an indirect way by comparing simulations with two-step cascade spectra from neutron capture experiments. In {sup 116,117}Sn an increase in the slope of the radiative strength function around E{sub {gamma}} = 4.5 MeV indicates the onset of resonance-like structures in both nuclei, resulting in a significant enhancement of the radiative strength functions compared to standard models in the energy region 4.5