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Excited states of the odd-odd nucleus 158Tb have been studied via the 154Sm(7Li ,3n) 158Tb reaction at a beam energy of 27 MeV. The new level scheme of 158Tb involving a positive parity rotational band is established up to excitation energy ∼2.3 MeV and spin ∼17ħ. By comparing with the rotational bands in the neighboring nuclei 157Tb and 157Gd, the configuration was tentatively assigned as πd5/2⊗ vi13/2 , and the phenomenon of signature inversion is discussed. [ABSTRACT FROM AUTHOR]

Three-dimensional fast magnetic reconnection driven by two ultraintense femtosecond laser pulses is investigated by relativistic particle-in-cell simulation, where the two paralleled incident laser beams are shot into a near-critical plasma layer to form a magnetic reconnection configuration in self-generated magnetic fields. A reconnection X point and out-of-plane quadrupole field structures associated with magnetic reconnection are formed. The reconnection rate is found to be faster than that found in previous two-dimensional Hall magnetohydrodynamic simulations and electrostatic turbulence contribution to the reconnection electric field plays an essential role. Both in-plane and out-of-plane electron and ion accelerations up to a few MeV due to the magnetic reconnection process are also obtained. [ABSTRACT FROM AUTHOR]

We report the measurement of one-neutron stripping to excited-state cross sections from the weakly bound projectile 6Li to the 96Zr target at near-barrier energies by the online γ -ray spectroscopy method. Transitions of the 97Zr nucleus were clearly identified by γ -γ coincidences. This cross section was found to be much smaller than the previously reported complete-fusion cross section for this system at energies above the barrier, whereas it becomes of the same magnitude around the Coulomb-barrier energy. No evidence of two-neutron transfer was found. We also performed coupled reaction channel calculations for the one-neutron stripping process. The calculation results are discussed. [ABSTRACT FROM AUTHOR]

Measurements of complete and incomplete fusion cross sections for 6Li+ 154Sm have been performed at energies above the Coulomb barrier by the online γ-ray method, to investigate the effect of breakup and inelastic couplings on the complete fusion (CF) of this weakly bound system. We show that inelastic excitation couplings have non-negligible effects, when compared with the breakup effect, for deformed nuclei at energies very close to the Coulomb barrier. The average CF suppression corresponding to dynamic breakup effects was found to be around 35%. The total fusion cross section is not affected by the breakup coupling. A comparison between the 6Li-induced CF suppression for three different samarium isotopes shows that the breakup effect is larger for the more spherical isotope. [ABSTRACT FROM AUTHOR]

The measurements of complete fusion cross sections for 6Li + 96Zr have been performed at energies around the Coulomb barrier by the online y-ray method. The complete fusion cross sections at above-barrier energies were found to be suppressed by ~25%. A comparison of the systematics of complete fusion suppression with the existing data for 6Li+ heavy targets with the present results shows that the systematics of the suppression factor observed for 6Li-induced fusion in the heavy mass region may not be consistent in lighter target mass region. [ABSTRACT FROM AUTHOR]

A three-dimensional elemental carbon kagome lattice, made of only fourfold-coordinated carbon atoms, is proposed based on first-principles calculations. Despite the existence of 60° bond angles in the triangle rings, widely perceived to be energetically unfavorable, the carbon kagome lattice is found to display exceptional stability comparable to that of C60. The system allows us to study the effects of triangular frustration on the electronic properties of realistic solids, and it demonstrates a metal-insulator transition from that of graphene to a direct gap semiconductor in the visible blue region. By minimizing s-p orbital hybridization, which is an intrinsic property of carbon, not only the band edge states become nearly purely frustrated p states, but also the band structure is qualitatively different from any known bulk elemental semiconductors. For example, the optical properties are similar to those of direct-gap semiconductors GaN and ZnO, whereas the effective masses are comparable to or smaller than those of Si. [ABSTRACT FROM AUTHOR]

High-spin states in 92Nb have been investigated by using in-beam γ ray spectroscopy with the 82Se(14N,4n)92Nb reaction at a beam energy of 54 MeV. The positive-parity decay sequences above the previously known state 13+ have been extended to Iπ≥(20+) by adding nineteen new γ rays. The level structures in 92Nb have been interpreted in terms of the shell model calculations performed in the configuration space π(1f5/2,2p3/2,2p1/2,1g9/2) for the protons and ν(2p1/2,1g9/2,1g7/2,2d5/2) for the neutrons. The calculated results show that the inclusion of proton core excitation relative to the Z=38 subshell closure and neutron particle-hole excitation for the N=50 shell closure are essential to adequately describe the experimental high-spin states at I≈(18-20)ℏ with excitation energies above 8.5 MeV. [ABSTRACT FROM AUTHOR]

High-spin level structures of 199Tl have been studied by in-beam γ-ray spectroscopic methods using the 196Pt(7Li, 4n)199Tl reaction at 40 MeV of beam energy. A large number of new states have been found, resulting in a significant extension of the previously known level scheme with the observation of 44 new transitions and 33 new levels. By comparing with the level structures in the odd-mass Tl isotopes and the even-even core Hg nuclei, configurations are proposed for the newly observed rotational bands and states in 199Tl. The properties of the strongly coupled positive- and negative-parity bands can be interpreted in terms of the cranked Nilsson-Strutinsky-Bogoliubov model calculations, which show that the observed bands are built on the oblate shapes. [ABSTRACT FROM AUTHOR]

The existing experimental value of the ratio B4/2=B(E2;41+→21+)/B(E2;1+→01+) in 134Ce is less than unity, which is outside the range allowed by current collective models and is highly anomalous. In the present work, new lifetime measurements of excited states in 134Ce have been performed in order to clarify this discrepancy. Excited states of 134Ce were populated by the fusion-evaporation reaction 122Sn(16O,4n)134Ce. The recoil distance doppler shift method was employed, and reliable lifetimes for the 21+, 41+, 102+, and 122+ states were derived from the differential decay curve method. The resulting B4/2 value is larger than unity, resolving the disagreement with traditional collective models. The new experimental data is in very good agreement with the calculation in the framework of the interacting boson model. The systematic evolution in collectivity of the Ce isotopes is discussed. [ABSTRACT FROM AUTHOR]

Lifetime measurements of yrast levels in 167W were measured using the recoil-distance Doppler-shift method. The differential decay-curve method was applied for a lifetime determination. Excited states of the nucleus 167W were populated by the reaction 142Nd (28Si28, 3n) at a beam energy of 144 MeV. The energy spectra and measured transition quadrupole moments inferred from the lifetimes of 167W are compared with the predictions of the cranked Nilsson-Strutinsky-Bogoliubov calculations. The changes of deformations and shapes with increasing spin due to the γ-polarization effect of aligned particles are discussed. The signature inversion visible in the negative parity yrast band is explained to be related to the triaxial shapes. [ABSTRACT FROM AUTHOR]

Lifetimes of the yrast states in 180Pt have been measured from 4+ to 8+ using the recoil distance Doppler-shift technique in the coincidence mode. These states were populated by the reaction 156Gd(28Si,4n)180Pt at a beam energy of 144 MeV. The differential decay curve method was applied to determine the lifetimes from experimental coincidence data. The B(E2) values extracted from lifetimes increase with increasing spin, implying rotor behavior, but do not show the typical shape coexistence where the B(E2) values present a rapid increase at very low spins. Calculations based on the triaxial projected shell model were performed for the yrast states in 180Pt and the results of both energies and E2 transition probabilities reproduce the experimental data very well. The result also shows that a better description of the yrast band in 180Pt requires consideration of the γ degree of freedom. [ABSTRACT FROM AUTHOR]