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[en] The reduced E2 and E4 transition matrix elements were measured for /sup 156,158/Dy, /sup 162,164/Er, and ¹⁶⁸Yb via Coulomb excitation with α particles at energies below these where nuclear effects are expected to significantly contribute. Charge deformation parameters β/sup c/₂ and β/sup c/₄ were extracted from these matrix elements by assuming the charge distribution to have a deformed Fermi distribution form with quadrupole and hexadecapole components. Values of <0⁺parallel (E2) parallel2⁺> of 1.929, 2.161, 2.238, 2.341, and 2.402 eb were found for /sup 156,158/Dy, /sup 162,164/Er, and ¹⁶⁸Yb, respectively, with 9 or approx. =1% uncertainty. The values of <0⁺parallelM (E4) parallel4⁺> for these same respective nuclei are 0.21/sup +0.16//sub -0.15/, 0.16/sup +0.10//sub -0.15/, 0.16/sup +0.14//sub -0.26/, 0.12/sup +0.12//sub -0.13/, and 0.19/sup +0.14//sub -0.19/ eb²

[en] The vibrational states of ^156,158Dy, ^162,164Er, and ¹⁶⁸Yb have been studied via Coulomb excitation. Thin high purity targets were prepared in an isotope separator. The Coulomb excitation of these nuclei was studied by the scattering of 12--16 MeV α particles, which were detected in an Enge splitpole spectrograph. The reduced transition probabilities B(Elambda;0_g.s.⁺→I^πK) were obtained for I^πK = 2⁺2, 2⁺0, and I^π = 3^- states in each nucleus. Limits on B(Elambda) values and values extracted from published (d,d') cross sections are also presented. Trends in B(E2) values and energy levels for the Dy, Er, and Yb nuclei show that the K^π = 2⁺ levels are reasonably constant in energy for only Dy and Er. In all three nuclei B(E2) values decrease with increasing neutron number. Except for the Dy isotopes, the lightest isotope has the largest B(E2) value for the lowest lying I^πK = 2⁺0 state. I^π = 3^- states level energies and B(E3) values are found to be in fair agreement with microscopic calculations. Values of B(E2) for K^π = 2⁺ states are in fair agreement with microscopic calculations when these exist

[en] Low- and high-spin states of ⁶⁸Ge are investigated through in-beam γ-ray spectroscopy via the ⁵⁸Ni(¹²C,2p), ⁶³Cu(⁷Li,2n), and ⁵²Cr(¹⁹F,p2n) reactions. A surprising richness of collective bands is observed in ⁶⁸Ge including three even parity bands built on 8⁺ levels, the lower two of which are assigned as rotational aligned bands built on both proton and neutron (g/sub 9/2/)² configurations, and three odd parity bands built on π and ν configurations that include the g/sub 9/2/ orbit. Details of the multiple bands and other levels observed in ⁶⁸Ge are presented. Rotation-aligned model calculations and interacting boson model calculations for ⁶⁸Ge are also described

[en] Details of the identification of ¹⁸⁶Tl and its decay to ¹⁸⁶Hg as investigated with an isotope separator are presented. Conversion electrons, γ, γ-γ, and e-γ studies establish two bands in ¹⁸⁶Hg; one built on a near-spherical ground state and one on a more strongly deformed shape with a band head at 522 keV. The levels are discussed in the framework of recent theoretical calculations

[en] New isotopes ¹⁸⁶,¹⁸⁸Tl (T₁/₂¹⁸⁶=4.5/sub -//sub 1/./sub 5/⁺¹.⁰ and 28plus-or-minus2 sec and T₁/₂¹⁸⁸=71plus-or-minus1 sec, respectively) have been identified. Conversion-electron, γ, γ-γ, and e-γ studies helped establish in ¹⁸⁶,¹⁸⁸Hg two bands, one built on a slightly deformed ground state and one on a more strongly deformed shape with 0⁺ band heads at 522 and 824.5 keV, respectively. Their crossing explains the anomalous behavior of I in the yrast cascades. States above and below the crossing in both bands support the existence of a well-defined second minimum in ¹⁸⁸Hg