The mean lifetimes of the 25/2(+), 21/2(+), and 17/2(+) states in the highly deformed (HD) band of Nd-133, excited via the reaction Pd-104(S-32,2pn)Nd-133, have been measured using a recoil distance Doppler-shift method. The decay out of the HD band occurs as a result of an admixture of normally deformed (ND) components into the HD states' wave function. The consistency in the mixing amplitude was assessed from the measured lifetimes, branching ratios, and quadrupole moments of the HD and the ND bands. This analysis unequivocally confirms the earlier approach to explain the decay-out mechanism.

The competition and cooperation of g(9/2) proton holes and neutron particles in high-j and low-j orbits has been studied by means of extensive lifetime measurements of high-spin states in Cd-102,Cd-104. The competition leads to strongly retarded E2 strengths between states below spin 8, while the spin alignment of proton holes and neutrons above spin 10 results in magnetic dipole bands with M1 strengths of 0.2-2 Wu. Shell model and Interacting Boson plus Broken Pair model calculations have been performed.

For the investigation of the collectivity and the structure of the intruder bands with positive and negative parity in 114Sn, coincidence lifetime measurements using the recoil distance Doppler shift (RDDS) and the Doppler-shift attenuation (DSA) methods were performed at the GASP spectrometer at the INFN-Laboratori in Legnaro. Excited nuclear states were populated with the reaction 100Mo(18O,4n)114Sn. For analysis the differential decay curve method was used in the γγ-coincidence mode. In total 31 lifetimes could be obtained, belonging to 11 and 13 states in the positive- and negative-parity intruder bands, respectively, and to 7 spherical states. This work enhances our knowledge of low-lying collectivity among the Sn isotopes near the mid-shell region.

The recoil-distance Doppler-shift and Doppler-shift attenuation techniques were employed to determine for the first time lifetimes of high-spin states in Cd-104 in the time range 0.3 ps less than or equal to tau less than or equal to1.2 ns. The nuclei were populated using the compound nucleus reaction Ni-58(Cr-50, 4p) and the gamma radiation from their decay was detected with the GASP spectrometer. A total of 34 reduced transition probabilities and limits for 18 further transitions were extracted providing a rich basis for a comparison with theoretical calculations. In addition, the lifetime data contained new information urging for a revision of the published level scheme of Cd-104. In particular, a magnetic dipole band recently established and interpreted as magnetic rotation is shown to he not existing. The new experimental results in Cd-104 are discussed in the frame of the interacting boson plus broken pair model.

Using the reaction Ni-58(Cr-50,alpha 2p) and the coincidence recoil distance Doppler shift technique, we determined picosecond lifetimes of high-spin states in Cd-102. The positive-parity yrast and yrare cascades evidence the competition and interplay of the two proton holes in the g(9/2) orbit and four neutrons in the d(5/2) g(7/2) and h(11/2) orbits, outside the Z = N = 50 Sn-100 core. At positive parity, this interplay leads to multiplets of states in the spin range 6(+)-10(-). some of which are connected by very weak E2 transitions. Al higher spins, spin-aligned proton holes and neutrons lead to magnetic rotation. Energies and transition strengths when compared with the predictions of several shell model calculations reveal the high sensitivity on the model parameters.

Lifetimes of some 20 high-spin states in Ag-101 in the range between 0.2 and 200 ps have been measured using various Doppler shift techniques, The states have been populated in the reaction Ni-58(Cr-50,alpha 3p) at 200-205 MeV beam energy and their decays observed by means of the GASP array. For many states, the problem of their unknown side-feeding times has been circumvented by using the DDCM and NGTB gamma gamma -coincidence methods. A total of some 60 reduced transition strengths or limits of them has been deduced. Moderately enhanced electric quadrupole transitions (up to 30 W.u.) have been derived as well as rather strong stretched magnetic dipole transitions within the negative parity yrast sequence (0.2-0.7) W.u. An attempt has been made to interpret the level energies and electromagnetic transitions within the interacting boson fermion plus broken pair model.

Results of a 208 Pb (γ,γ′) experiment are presented aiming at an identification of the 2 + member of the long-sought two-octupole phonon multiplet. Four E2 excitations have been observed below 6.5 MeV excitation energy, two of them for the first time. However, in contrast to new results of calculations within the quasiparticle–phonon nuclear model (QPM), no obvious candidate for the two-octupole phonon vibration could be found in the present study. We discuss the Jπ=2+ states detected in this as well as previous experiments with respect to their possible two-octupole phonon structure.

The electric dipole strength distributions below threshold in stable even-mass Pb isotopes have been extracted from photon scattering experiments at the superconducting Darmstadt electron linear accelerator S-DALINAC. Between 4 and 6.5 MeV excitation energy a resonance-like clustering of strength is observed. A strong evolution of a fragmentation of the dipole strength with opening the neutron shell is found. The fine structure of the strength is compared to microscopic quasiparticle-phonon model calculations that quantitatively reproduce the data quite well and explain the fragmentation of the dipole strength. Models suggesting the oscillation of excess neutrons with respect to an N≃Z core as a possible origin of low-lying E1 strength are critically examined.

Picosecond lifetimes in Ba-129.130 were determined using the recoil distance technique with a plunger device coupled to an array of EUROBALL-cluster-detectors for the first time. The differential decay curve method in coincidence mode was employed to derive lifetimes for six states in Ba-129 and twelve states in Ba-130. The resulting B(E2) Values are compared with triaxial rotor plus particle calculations for Ba-129 and, in Ba-130, to the predictions of the general collective model, the interacting boson model, as well as to the symmetric and asymmetric rotor models. In Ba-130, the transitional quadrupole moment in the ground state hand is remarkably constant before and after the backbend. With this data the two-quasiparticle negative parity band in Ba-130 was confirmed to be based on a pi(h(11/2)xd(5/2)/g(7/2)) configuration.

Single-particle states as well as collective states in the natural Bismuth isotope 209Bi were investigatedusing two Euroball Cluster detectors at the Cologne FN-tandem accelerator. The states were populated by the subcoulomb proton stripping reaction 208Pb(3He,d*γγ)209Bi at 20.5 MeV beam-energy. Forty-eight γ-transitions and 33 levels were observedfor the first time. Gamma-transitions up to an energy of 6.0 MeV were detected. The energy of the observed states were determined to an accuracy of about 0.3 keV.

A nuclear resonance fluorescence experiment on 88Sr has been performed with bremsstrahlung of 6.7 MeV endpoint energy. The γ-ray linear polarisation has been measured with a EUROBALL CLUSTER detector used as a Compton polarimeter. The results indicate positive parity for the J= 1 state at 4.742 MeV in 88Sr, in contrast to the previous interpretation as a 1− two-phonon (2+1⊗ 3−1) state and in conflict with the predictions of the quasiparticle-phonon model. On the basis of such calculations the 1+ state at 3.486 MeV may be considered as the 1+1 one-phonon state and the very strong 1+1→ 0+1 deexcitation as proton spin-flip 2p1/2→ 2p3/2 transition.

Picosecond lifetimes in ${}^{129,130}\mathrm{Ba}$ were determined using the recoil distance technique with a plunger device coupled to an array of EUROBALL-cluster-detectors for the first time. The differential decay curve method in coincidence mode was employed to derive lifetimes for six states in ${}^{129}\mathrm{Ba}$ and twelve states in ${}^{130}\mathrm{Ba}.$ The resulting $B(E2)$ values are compared with triaxial rotor plus particle calculations for ${}^{129}\mathrm{Ba}$ and, in ${}^{130}\mathrm{Ba},$ to the predictions of the general collective model, the interacting boson model, as well as to the symmetric and asymmetric rotor models. In ${}^{130}\mathrm{Ba},$ the transitional quadrupole moment in the ground state band is remarkably constant before and after the backbend. With this data the two-quasiparticle negative parity band in ${}^{130}\mathrm{Ba}$ was confirmed to be based on a $\ensuremath{\pi}{(h}_{11/2}\ensuremath{\bigotimes}{d}_{5/2}{/g}_{7/2})$ configuration.