Half-life measurements of several states inSr95,97,Zr97,100,

Abstract

Half-lives T 1/2 of states in 95,97 Sr, 97,100,104 Zr, 106 Mo, and 148 Ce, which decay by delayed γ transitions, were determined by using a new time-gated triple γ coincidence method. Transition energy dependent effects such as time walks, time jitters, amplitude walks, and possible timing fluctuations of Ge detectors that contribute to the width of the time window were taken into consideration by comparing prompt and delayed cascades with similar transition energies. It is shown that the normalized triple γ coincidence counts of two prompt cascades with similar transition energies are similar. Also, it is observed that the real triple γ coincidence counts in the prompt cascades change systematically with the widths of the coincidence time window and the transition energies. Half-lives of states in 100,104 Zr were measured for the first time. The half-lives of states in the delayed cascades were determined by using the prompt cascades with transition energies similar to those in delayed cascades. The half-life of the 2 + state in 104 Zr is measured to be 2.0(3) ns. The B(E2; 2 + → 0 + )(e 2 b 2 ) value and quadrupole deformation β 2 are 0.40(6) (e 2 b 2 ) and 0.47 (7), respectively. 104 Zr has the most deformed 2 + state among medium and heavy even-even nuclei, except for 102 Sr. This method is only approximately valid, but it is believed to be generally within 10% of the true value.

Dissipative dynamics in quasifission

“…2a which cannot be explained with such simple considerations. havior may be due to the fact that Zr isotopes (Z = 40) in the mass range 100 − 112 are strongly bound with a large prolate deformation around β 2 = 0.42 [48][49][50]. Due to shell effects, these configurations may be energetically favorable during the QF dynamics [16,17,19].…”

Tensor part of the Skyrme energy density functional. II. Deformation properties of magic and semi-magic nuclei

“…A large set of experimental data (charge radii [69], rotational bands [73] and B(E2) values [74]) demonstrate that 100 Zr is located in a region of deformed nuclei. An excited band built on a 0 + state coexisting with the ground-state band [73], and the large E0 transition strength between the 0 + states [75] indicate the coexistence of shapes with different deformations, the state with the largest deformation being the ground state.…”

Tetrahedral shapes of neutron-rich Zr isotopes from a multidimensionally constrained relativistic Hartree-Bogoliubov model

“…By including the β 30 deformation, a pear-like ground state of 112 Zr is predicted with the functional DD-PC1 [21]. From the experimental point of view, the analysis of rotational bands, β-decay half-lives, and lifetimes of the first 2 + states reveals that some of these nuclei are well deformed [62,[152][153][154][155][156][157][158][159][160][161][162][163][164] Next we give some numerical details and illustrative calculations of the MDC-RHB model. Then we present and discuss the results for neutron-rich even-even Zr isotopes calculated with functionals DD-PC1 [111] and PC-PK1 [166].…”

“…Several experiments were devoted to the study of tetrahedral shapes in 160 Yb [58], 154,156 Gd, although the observed odd and even-spin members of the lowest energy negative-parity bands are similar to the proposed tetrahedral band of 156 Gd, the deduced nonzero quadrupole moments existence of tetrahedral shapes in these nuclei. The possibility of a tetrahedral shape for the negative-parity bands in 230,232 U was excluded in Ref.…”

“…Various nuclei such as 80,108,110 Zr, 160 Yb, 156 Gd, and 242 Fm were predicted to have ground or isomeric states with tetrahedral shapes from the macroscopicmicroscopic (MM) model [40,41,45,49,50] and the Skyrme Hartree-Fock (SHF) model, the SHF plus BCS model, or the Skyrme Hartree-Fock-Bogoliubov (SHFB) model [38, 39, 41-43, 45, 49, 51]. The possible existence of tetrahedral symmetry in light nuclei such as 16 O [52] as well as superheavy nuclei [53,54] was also proposed.…”