RUI: Structure Evolution in the Tellerium Isotopic Chain

United States Naval Academy- Do Not Use, Annapolis MD

Investigators

Abstract

Tellurium has a wide range of abundant stable isotopes. The tellurium nuclei have two valence protons with respect to Z = 50 and a range of neutron numbers. Three different types of structure are thought to be active in these nuclei:collective, two-particle, and particle-hole excitations known as intruders. Because there are seven stable even-even Te nuclei, one can study the evolution of these excitation modes over a wide range in neutron number. Emphasis centers on understanding the interplay between particle and collective features and on the aspects of the nuclear forces and shell model orbitals that determine the relative importance. Several models are now able to reproduce the level scheme. Often level energies are more important for evaluating whether a model has sufficient built-in complexity rather than distinguishing between physical descriptions. Transition rate information is crucial to revealing the amplitudes of particle and collective components in the wavefunctions. Excited levels in 130Te below 3.3 MeV will be studied at the University of Kentucky Nuclear Structure Laboratory utilizing inelastic neutron scattering techniques. Electromagnetic transition rates,multipole mixing and branching ratios, and level spins and parities will be deduced from measured gamma-ray excitation functions, coincidences,angular distributions, and Doppler shifts. The excited levels in 118Te and 120Te will be studied at the University of Cologne. The low-spin level scheme will be first verified with gamma-ray spectroscopy following a few-neutron emission reaction. The lifetimes of states in 118Te and 120Te will then be determined using the recoil-distance Doppler shift technique.