ISBN 9783868539042

978-3-86853-904-2, Reihe Physik

Wolfram Rother
Lifetime Measurements in 62,64,66Fe

107 Seiten, Dissertation Universität Köln (2011), Softcover, A5

Zusammenfassung / Abstract

This work reports on model-independent lifetime measurements of the first 2+ states in 62,64,66Fe at the National Superconducting Cyclotron Laboratory. While confirming the known value for 62Fe, the experiment on 64Fe could reduce the experimental error significantly. The lifetime of the first 2+ state in 66Fe was not known beforehand. Excited states were populated by inverse kinematics Coulomb excitation after projectile fragmentation. To account for Doppler shift attenuation in target and degrader, relativistic Lorentz Boost and solid angle related effects, a dedicated simulation tool was written. The program reproduces the line-shape of detected gamma-rays using a discretisation approach. Collectivity around N = 40 is discussed based on the new and on older B(E2) data. The new values confirm the rising collectivity in iron isotopes at N = 38, that was recently reported. More so, the drastic reduction of the experimental error puts this statement on a sound footing. The present data on 66Fe were the first to show the persistence of enhanced collectivity in the iron chain at N = 40. While numerical calculations for this region of the nuclear chart were not successful in the past, the purely phenomenological approach of the modified Valence

Proton Symmetry yields a rather good description of collective nuclei around N = 40. The state-of-the-art effective LNPS interaction is basis for a beautiful shellmodel description of the new data set. Improvements on the interaction and on the computational power side allow for a very detailed description of collective nuclei far from the valley of stability.