Lifetime determination of excited states in Cd-106

Two separate experiments using the Differential Decay Curve Method have been performed to extract mean lifetimes of excited states in 106 Cd. The inedium-spin states of interest were populated by the Mo-98(C-12, 4n) Cd-106 reaction performed at the Wright Nuclear Structure Lab., Yale University. From this experiment, two isomeric state mean lifetimes have been deduced. The low-lying states were populated by the Mo-96(C-13, 3n)Cd-106 reaction performed at the Institut fur Kernphysik, Universitat zu Koln. The mean lifetime of the I-pi = 2(1)(+) state was deduced, tentatively, as 16.4(9) ps. This value differs from the previously accepted literature value from Coulomb excitation of 10.43(9) ps

\u3cem\u3eγ\u3c/em\u3e-ray Spectroscopy of \u3csup\u3e166\u3c/sup\u3eHf: X(5) in \u3cem\u3eN\u3c/em\u3e \u3e 90?

Excited states in 166Hf were populated in the β+/∈ decay of 166Ta and studied through off-beam γ –ray spectroscopy at the Yale moving tape collector. New coincidence data found no support for two previously reported excited 0+ states and led to a substantially revised level scheme. Similarities between the revised level scheme of 166Hf and the X(5) critical point symmetry are discussed, and the extent of X(5) behavior in this mass region is explored through the W and Os isotopes. Among X(5) candidates with N \u3e 90, good agreement is observed for most energies and interband B(E2) strengths, while all exhibit similar disagreements with other key observables, in particular, yrast B(E2) values and spacing in the excited K = 0+ sequence

Revisiting anomalous \u3cem\u3eB\u3c/em\u3e(\u3cem\u3eE\u3c/em\u3e2;4\u3csup\u3e+\u3c/sup\u3e\u3csub\u3e1\u3c/sub\u3e→2\u3csup\u3e+\u3c/sup\u3e\u3csub\u3e1\u3c/sub\u3e)/\u3cem\u3eB\u3c/em\u3e(\u3cem\u3eE\u3c/em\u3e2;2\u3csup\u3e+\u3c/sup\u3e\u3csub\u3e1\u3c/sub\u3e→0\u3csup\u3e+\u3c/sup\u3e\u3csub\u3e1\u3c/sub\u3e) values in \u3csup\u3e98\u3c/sup\u3eRu and \u3csup\u3e180\u3c/sup\u3ePt

Recently, a set of nine nonmagic nuclei with anomalous values of the B(E2) ratio B4/2 ≡ B(E2; 4+1 → 2+1)/B(E2; 2+1 → 0+1) were identified. Such values are outside the range allowed by current collective models. In the present work, the B(E2; 4+1 → 2+1) values for two of these nuclei, 98Ru and 180Pt, were re-measured to determine if the current literature values for these nuclei are correct. 98Ru was studied in a 27Al(98Ru,98Ru∗) Coulomb excitation experiment in inverse kinematics, while the lifetime of the 4+1 state in 180Pt was measured in a 122Sn(62Ni, 4n)180Pt recoil distance method (RDM) experiment. For both nuclei, the remeasured B4/2 values are well above 1, removing the deviations from collective models

Isomeric Decay of \u3csup\u3e208\u3c/sup\u3eRa

Low-energy excited states of 208Ra were investigated using the 182W(30Si, 4n) reaction at the Wright Nuclear Structure Laboratory of Yale University. Fusion evaporation recoils were selected using the gas-filled spectrometer SASSYER. Delayed γ rays, following isomeric decays, were detected at the focal plane of SASSYER with a small array of three clover Ge detectors. Transitions following a proposed J π = 8+ isomer were observed, and the half-life was measured

\u3cem\u3eg\u3c/em\u3e Factor of the 2\u3csup\u3e+\u3c/sup\u3e\u3csub\u3e1\u3c/sub\u3e State of \u3csup\u3e170\u3c/sup\u3eHf

The g factor of the 2+1 state of 170Hf was measured by perturbed γ-γ angular correlation in a static external magnetic field. The result, g(2+1) = 0.28(5), extends the systematics of g factors of even-even Hf isotopes to N = 98 and enables a better test of theoretical models. The g(2+1) experimental values of these isotopes exhibit a remarkable constancy as a function of neutron number. This phenomenon, which was also observed for other isotopic chains in the Gd–W range, is explained in terms of a recently proposed empirical model

Isomers and Seniority in the Trans-Pb Nuclei

Low-energy excited states of 210Ra and 208Ra were investigated at the Wright Nuclear Structure Laboratory of Yale University. Fusion evaporation recoils were selected using the gas-filled spectrometer, SASSYER. Delayed γ -rays, following isomeric decays, were detected at the focal plane of SASSYER with a small array of HPGe detectors. Transitions following the proposed J π = 8+ isomers were observed, and the half-lives measured. The experiments are discussed and results compared to expectations from the seniority scheme

Enhanced Mixing of Intrinsic States in Deformed Hf Nuclei

Excited low-spin, nonyrast states in 170,172,174Hf were populated in β + /∈decay and studied through off-beam γ-ray spectroscopy. New coincidence data allowed for a substantial revision of the level schemes of Hf170,172 and a confirmation of the level scheme of 174Hf. The Hf isotopes represent a unique situation in which a crossing of collective intrinsic excitations occurs, enhancing significantly the effects of mixing. Using branching ratios from excited 2+ states, this mixing is followed and studied. The resulting mixing matrix elements are found to be ∼30 keV—an order of magnitude larger than estimated previously for nearby nuclei. In the case of 170Hf, the 2+β and 2+γlevel are shown to be completely mixed