Backbending in Dy isotopes within the Projected Shell Model

A systematic study of the yrast band in 154-164 Dy isotopes using the Projected Shell Model is presented. It is shown that, in the context of the present model, enlarging the mean field deformation by about 20 % allows a very good description of the spectrum of yrast band in these isotopes. The dependence of the B(E2) values on angular momentum is also better described when larger deformations are used. The observed oscillation of g-factors at low spin states remains an open question for this model.Comment: 17 pages, 7 figures, submitted to Phys. Rev.

Perturbed angular correlations for Gd in gadolinium: in-beam comparisons of relative magnetizations

Perturbed angular correlations were measured for Gd ions implanted into gadolinium foils following Coulomb excitation with 40 MeV O-16 beams. A technique for measuring the relative magnetizations of ferromagnetic gadolinium hosts under in-beam conditions is described and discussed. The combined electric-quadrupole and magnetic-dipole interaction is evaluated. The effect of nuclei implanted onto damaged or non-substitutional sites is assessed, as is the effect of misalignment between the internal hyperfine field and the external polarizing field. Thermal effects due to beam heating are discussed.Comment: 37 pages, 15 figures, accepted for publication in NIM

Transient field g factor and mean-life measurements with a rare isotope beam of 126Sn

Background: The g factors and lifetimes of the 21+ states in the stable, proton-rich Sn isotopes have been measured, but there is scant information on neutron-rich Sn isotopes. Purpose: Measurement of the g factor and the lifetime of the 21+ state at 1.141 MeV in neutron-rich 126Sn (T1/2=2. 3×105y). Method: Coulomb excitation in inverse kinematics together with the transient field and the Doppler shift attenuation techniques were applied to a radioactive beam of 126Sn at the Holifield Radioactive Ion Beam Facility. Results: g(21+)=-0.25(21) and τ(21+)=1.5(2) ps were obtained. Conclusions: The data are compared to large-scale shell-model and quasiparticle random-phase calculations. Neutrons in the h11/2 and d3/2 orbitals play an important role in the structure of the 21+ state of 126Sn. Challenges, limitations, and implications for such experiments at future rare isotope beam facilities are discussed

Low-energy structure of the even-A 96−104 Ru isotopes via g-factor measurements

The transient-field-perturbed angular correlation technique was used with Coulomb excitation in inverse kinematics to perform a systematic measurement of the g factors of the first excited 21+ states in the stable even-A isotopes Ru96-104. The measurements have been made relative to one another under matched kinematic conditions and include a measurement of g(21+)=+0.47(3) in Ru96

Electromagnetic properties of the 21+ state in 134Te: Influence of core excitation on single-particle orbits beyond 132Sn

The g factor and B(E2) of the first excited 2+ state have been measured following Coulomb excitation of the neutron-rich semimagic nuclide 134Te (two protons outside 132Sn) produced as a radioactive beam. The precision achieved matches related g-factor m

Decay history and magnetic moments at high spin in Dy152

Average magnetic moments as well as information on the time evolution of the continuum structure of Dy152 at high spin have been obtained using the transient hyperfine magnetic field acting on fast ions traversing a thin, magnetized gadolinium foil. Dy152 nuclei were populated by the Ge76(80Se,4n)152Dy fusion-evaporation reaction at E(80Se)=326.5 MeV. The target-ferromagnet arrangement corresponds to a time window of about 701200 keV, rays contributing to the collective E2 bump, exhibit a negligible precession, in accordance with the very short lifetimes of these states. The precession of the angular distribution of discrete yrast rays deexciting the nucleus from spin I35Latin small letter h with stroke down yields an average magnetic moment for states with 43Latin small letter h with strokeI31Latin small letter h with stroke. The resulting g=0.21(2) is considerably lower than the collective value Z/A0.43 and indicates an appreciable contribution from aligned neutrons to the lower-spin region populated within the above time frame. The results are discussed in the framework of model calculations of the -ray cascade

G factor of the 59/2 - isomer in Gd147

The g factor of the 10 995 keV, Je=(59/2-, and T1/2=0.8 ns level in Gd147 has been determined by the transient field method for ions recoiling through a magnetized Gd foil at a temperature of 100 K. The Ge76(76Ge,5n)147Gd reaction at E(76Ge)=310 MeV was used to provide high recoil velocity. A 100 ps flight time in vacuum between the target and the ferromagnet of 100 ps ensured that the -ray cascades fed the (59/2 level before the recoil ions traversed the Gd foil. The g factor was extracted from standard double ratios with the known parametrization of the transient field, yielding g=0.38(7). This value is in agreement with the predicted wave function and experimental single-particle moments in this mass region. Results for levels in 146,148Gd were also obtained

Single particle signatures in high-spin, quasi continuum states in 193,194 Hg from g-factor measurements

The average g factors of high spin, high-excitation energy, quasi continuum structures in 194,193Hg were measured by observing the precessions of the angular distributions of γ-ray transitions in several normal-deformation bands that coalesce in the decay of the entry distribution of states. The average g factors of the states leading to the three main bands in the 193,194Hg isoles were: 〈g(193Hg)〉 = +0.19(1) and 〈g(194Hg)〉 = +0.26(1), respectively. These average g factors are smaller than the average of the g factors of the high energy states in the three superdeformed bands of 194Hg, 〈g(SD;194Hg)〉 = +0.41(8). While the nucleus in the superdeformed well behaves like a rigid rotor, the present results demonstrate the important role played by multiple, quasi particle neutron configurations in the structure of normal-deformation, highly-excited nuclear states

First direct measurements of g factors of the three superdeformed bands of 194Hg

The average g factors of the high-energy states of the three superdeformed bands in 194Hg were determined directly in a transient field experiment. The reaction 150Nd(48Ca,4n)194Hg at a beam energy of 203 MeV was used to provide recoiling reaction product nuclei with sufficient velocity to traverse a gadolinium ferromagnetic layer. The resulting g factors g(SD1)50.36(10), g(SD2)50.41(20), and g(SD3)50.71(26) are in agreement with cranked Hartree-Fock calculations as well as with the picture of a rigid rotation for which g 5Z/A