Evolution of the One-Quadrupole Phonon 2+_1,ms Mixed-Symmetry State in 124,126,128,130,132Xe.
Technische Universität, Darmstadt
[Ph.D. Thesis], (2010)
Available under Creative Commons Attribution Non-commercial No Derivatives, 2.5.
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|Item Type:||Ph.D. Thesis|
|Title:||Evolution of the One-Quadrupole Phonon 2+_1,ms Mixed-Symmetry State in 124,126,128,130,132Xe|
Collective nuclei are characterized by rotational and vibrational states due to a common and therefore ``collective'' behavior of the two constituents of the nucleus: protons and neutrons. The evolution of the collectivity (spontaneous deformation) is governed by the proton-neutron interaction in the valence shell. Nuclear states that are particularly sensitive to the proton-neutron interaction in the valence shell are the so called mixed symmetry states (MSSs). In this work we trace the evolution of the fundamental MSS, i.e the one-quadrupole phonon 2+_1,ms state, in a transitional region from vibrational nuclei (134Xe) to gamma-soft nuclei reflecting the O(6)-like structure of the IBM-2 (124,126Xe). Projectile-Coulomb excitation of Xe isotopes has been performed at Argonne National Laboratory (ANL) using the Gammasphere array for the detection of gamma-rays. First, our data on more than 50 absolute E2 transition rates between off-yrast low-spin states of 124,126Xe enable us to quantitatively test O(6) symmetry in these two nuclei. As a result we find that O(6) symmetry is more strongly broken in the A=130 mass region than previously thought. Then, 19 absolute E2 transition strengths have been obtained in 128Xe including the first measurement of the critical B(E2) decays from the second and third Jpi=0+ states. These data are compared with the theoretical predictions of the critical point symmetry E(5) and let us conclude that 128Xe is not an E(5) nucleus as previously suggested, leaving 130Xe as the most likely candidate amongst the xenon isotopes. Finally, the one-phonon 2+_1,ms states or at least a fragment of it have been identified in 128,130,132,134Xe. This enables us to trace the evolution of the one-phonon 2+_1,ms states in the even-even stable xenon isotopic chain from the vibrators near N=82 to the gamma-soft nuclei towards mid-shell.
|Place of Publication:||Darmstadt|
|Classification DDC:||500 Naturwissenschaften und Mathematik > 530 Physik|
|Divisions:||05 Department of Physics > Institute of Nuclear Physics|
|Date Deposited:||25 Jun 2010 08:55|
|Last Modified:||07 Dec 2012 11:57|
|Referees:||Pietralla, Prof. Dr. Norbert and Kröll, Prof. Dr. Thorsten|
|Refereed:||10 May 2010|