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The nuclear structure of the odd-mass 69Zn and 71Zn isotopes, with one hole or one particle outside the N=40 subshell closure, has been investigated by measuring the lifetime of excited states using the recoil distance Doppler-shift method. The nuclei of interest were produced in a deep-inelastic reaction in inverse kinematics with a 238U beam impinging on a 70Zn target. Single-particle and collective states were found to coexist at low energy in 69Zn and 71Zn. [ABSTRACT FROM AUTHOR]

A delayed, 76.5-keV transition has been observed in coincidence with 97Rb at the Lohengrin mass spectrometer via y-ray and conversion-electron spectroscopy. The multipolarity of the delayed transition was determined to be El and its measured half-life is 5.1(4) /xs. Comparisons with the results of Hartree-Fock-Bogoliubov and quasiparticle-rotor model calculations allow a spin and parity of (1/2, 3/2)- to be assigned to this state. The isomer is likely to be one of the low-lying prolate-deformed 3/2- [312], or oblate-deformed 1/2- [321], 3/2- [321] quasiparticle excitations. A new decay branch of the (9/2+), 830.8-keV isomer of 97Sr has also been observed in the same experiment, allowing a spin of (5/2)+ to be assigned to the 522.5-keV state. This level is likely to have a high-seniority spherical configuration [ABSTRACT FROM AUTHOR]

Excited states in 18C were populated by the one-proton knockout reaction of an intermediate energy radioactive 19N beam. The lifetime of the first 2+ state was measured with the KöIn/NSCL plunger via the recoil distance method to be τ(21+) = 22.4 ± 0.9(stat)-2.2+3.3(syst) ps, which corresponds to a reduced quadrupole transition strength of B(E2; 21+ → 01+ = 3.64-0.14+0.15(stat)-0.47+0.40(syst) e²fm4. In addition, an upper limit on the lifetime of a higher-lying state feeding the 21+ state was measured to be τ < 4.6 ps. The results are compared to large-scale ab initio no-core shell model calculations using two accurate nucleon-nucleon interactions and the importance-truncation scheme. The comparison provides strong evidence that the inclusion of three-body forces is needed to describe the low-lying excited-state properties of this A = 18 system. [ABSTRACT FROM AUTHOR]

The article presents the study which examined the lifetime excited-state transition-rate measurements in neutron-rich 18 carbon (C). In the study, the recoil distance method (RDM) lifetime measurements were used due to their reliability as model-independent probes of nuclear structure. The study was carried out at the Michigan State University's National Superconducting Cyclotron Laboratory (NSCL).

Lifetimes of the 9/21- and 3/21- states in 63Co and the 9/21- state in 65Co were measured using the recoil distance Doppler shift and the differential decay curve methods. The nuclei were populated by multinucleon transfer reactions in inverse kinematics. γ rays were measured with the EXOGAM Ge array and the recoiling fragments were fully identified using the large-acceptance VAMOS spectrometer. The E2 transition probabilities from the 3/21- and 9/21- states to the 7/2- ground state could be extracted in 63Co as well as an upper limit for the 9/21-→7/21- B(E2) value in 65Co. The experimental results were compared to large-scale shell-model calculations in the pf and pfg9/2 model spaces, allowing us to draw conclusions on the single-particle or collective nature of the various states. [ABSTRACT FROM AUTHOR]

Low-lying collective states in 126Xe have been investigated via the 12C(l26Xe,126Xe*) projectile Coulomb excitation reaction at 399 MeV. The y decays were detected with the Gammasphere array. Coulomb excitation cross sections relative to the 21+ state were obtained. Twenty-two absolute E2 transition strengths have been deduced. An sd-interacting boson model (IBM-1) fit agrees well with the new experimental data. This makes a quantitative test of O(6)-symmetry breaking in 126Xe possible. The measured absolute B(E2) values indicate a preservation of O(5) symmetry, while the O(6) symmetry is broken. The evolution of O(6)-symmetry breaking and of O(5)-symmetry conservation in the 124,126,128Xe isotopic chain is discussed. [ABSTRACT FROM AUTHOR]