Final Report for DE-FG52-03NA00076

Mitchell, G. E.

North Carolina State University

关键词: Isotopes;    Strength Functions Nuclear Level Densities;    Nuclear Reactions;    Radiative Stength Function;    Energy-Level Density;   

DOI  :  10.2172/893373
RP-ID  :  Final Report - Nuclear Level Densities and gamma-ray strength functions
RP-ID  :  FG52-03NA00076
RP-ID  :  893373

美国|英语

来源: UNT Digital Library

【 摘 要 】

Level densities and radiative strength functions are crucial for stewardship science, in particular for radiochemical studies. In addition, this information is key to undertanding nucleosynthesis and thus very important for astrophysics. We utilized a method derives simultaneously the nuclear level density and the radiative strength function for energy regions that are extremely difficult to study via other methods. In heavy nuclei there is evidence for the systematic appearance of a low energy resonance in the radiative strength function (the so-called pygmy resonance). We have studied the same final nuclide (171Yb) via different nuclear reactions and obtained the same energy and width for the pygmy resonance. We also extended the method to lighter nuclei, including 56,57Fe, 93-98Mo and 116,117Sn. For the iron and molybdenum isotopes an enhancement of the radiative strength function was observed at low energy. Subsequent measurements in iron appear to confirm this unusual effect. Our measurements in tin do not observe this enhancement, nor did any of the earlier measurements in heavy nuclei. The issue is still unsettled.