118448912
Description of collective and quasiparticle excitations in deformed actinide nuclei: The first application of the multishell shell model for heavy nuclei
The Heavy Shell Model (HSM) (Y. Sun and C.-L. Wu, Phys. Rev. C 68, 024315 (2003)) was proposed to take the advantages of two existing models, the projected shell model (PSM) and the Fermion Dynamical Symmetry Model (FDSM). To construct HSM, one extends the PSM by adding collective D-pairs into the intrinsic basis. The HSM is expected to describe simultaneously low-lying collective and quasi-particle excitations in deformed nuclei, and still keeps the model space tractable even for the heaviest systems. As the first numerical realization of the HSM, we study systematically the band structures for some deformed actinide nuclei, with a model space including up to 4-quasiparticle and 1-D-pair configurations. The calculated energy levels for the ground- state bands, the collective bands such as {\beta} - and {\gamma} -bands, and some quasiparticle bands agree well with known experimental data. Some low-lying quasiparticle bands are predicted, awaiting experimental confirmation.
119432492
Evolution of deformations in medium-mass nuclei
Evolution of quadrupole deformations in sd- and pf-shell nuclei with mass A=18-56 is studied by using deformed Skyrme Hartree-Fock model with pairing correlations. We point out that the quadrupole deformations of the nuclei with the isospin T=0 and T=1 show strong mass number dependence as a clear manifestation of dynamical evolution of deformation in nuclear many-body systems. The competition between the deformation driving particle-vibration coupling and the closed-shell structure is shown in a systematic study of the ratios between the proton and neutron deformations in nuclei with T=|T{sub z}|=1. Calculated quadrupole and hexadecapole deformations are compared with shell model results and available experimental data. A relation between the skin thickness and the intrinsic Q{sub 2} moments is also discussed.
121212177
Hypernuclei in the deformed Skyrme-Hartree-Fock approach
The properties of Lambda hypernuclei in a broad mass region are studied by using a deformed Hartree-Fock approach using realistic nucleonic Skyrme forces, pairing correlations, and a microscopically determined lambda-nucleon interaction based on Brueckner-Hartree-Fock calculations of hypernuclear matter. The results suggest that the core nuclei and the corresponding hypernuclei have similar deformations with the same sign. Some light single-Lambda hypernuclei are substantially deformed and the Lambda binding energy is modified by the deformation.
59153291
Shape evolution of Ne isotopes and Ne hypernuclei: The interplay of pairing and tensor interactions
We study tensor and pairing effects on the quadruple deformation of neon isotopes based on a deformed Skyrme-Hartree-Fock model with BCS approximation for the pairing channel. We extend the Skyrme-Hartree-Fock formalism for the description of hypernuclei adopting the recently-proposed ESC08b hyperon-nucleon interaction. It is found that the interplay of pairing and tensor interactions is crucial to derive the deformations in several neon isotopes. Especially, the shapes of 26,30 Ne are studied in details in comparisons with experimentally observed shapes. Furthermore the deformations of the hypernuclei are compared with the corresponding neon isotopic cores in the presence of tensor force. We find the same shapes with somewhat smaller deformations for single Λ-hypernuclei compared with their core deformations.
119370783
Effect of Tensor Force on the Halo Structure of 29Ne and 31Ne
The structure of Ne isotopes has been investigated by using deformed Skyrme–Hartree–Fock(SHF)method and BCS approximation.Especially the efect of tensor force on the halo structure of 29Ne and 31Ne is discussed.To this end,the tensor contributions are considered to the energy density function and the single particle potential in SHF theory.For comparison,four Skyrme interactions are used:SLy5 and SGII without tensor force,and SLy5+T and SGII+T with tensor force.The results indicate that the inclusion of tensor force shows a more pronounced halo structure for31Ne.
118278930
Tensor correlation, pairing interaction, and deformation in Ne isotopes and Ne hypernuclei
We study tensor and pairing effects on the quadruple deformation of neon isotopes based on a deformed Skyrme-Hartree-Fock model with BCS approximation for the pairing channel. We extend the SkyrmeHartree-Fock formalism for the description of single- and d ouble-lambda hypernuclei adopting two different hyperon-nucleon interactions. It is found that the inte rplay of pairing and tensor interactions is crucial to derive the deformations in several neon isotopes. Especi ally, the shapes of 26,30 Ne are studied in details in comparisons with experimentally observed shapes. Furthermore the deformations of the hypernuclei are compared with the corresponding neon isotopic cores in the presence of tensor force. We find the same shapes with somewhat smaller deformations for single Λ-hypernuclei compared with their core deformations. It is also pointed out that the latest version of hyper on interaction, the ESC08b model, having a deeper Λ potential makes smaller deformations for hypernuclei than those of another NSC97f model.
118669017
HARD X-RAY PHOTON INDEX AS AN INDICATOR OF BOLOMETRIC CORRECTION IN ACTIVE GALACTIC NUCLEI
We propose the rest-frame 2-10 keV photon index, {Gamma}{sub 2-10keV}, acting as an indicator of the bolometric correction, L {sub bol}/L {sub 2-10keV} (where L {sub bol} is the bolometric luminosity and L {sub 2-10keV} is the rest-frame 2-10 keV luminosity), in radio-quiet active galactic nuclei (AGNs). Correlations between {Gamma}{sub 2-10keV} and both bolometric correction and Eddington ratio are presented, based on simultaneous X-ray, UV, and optical observations of reverberation-mapped AGNs. These correlations can be compared with those for high-redshift AGNs to check for any evolutionary effect. Assuming no evolutionary effect in AGNs' spectral properties, together with the independent estimates of L {sub 2-10keV}, the bolometric correction, Eddington ratio, and black hole (BH) mass can all be estimated from these correlations for high-redshift AGNs, with the mean uncertainty of a factor of 2-3. If there are independent estimates of BH masses, {Gamma}{sub 2-10keV} for high-redshift AGNs can be used to determine their true L {sub bol} and L {sub 2-10keV}, and in conjunction with the redshift can be potentially used to place constraints on cosmology by comparison with the rest-frame 2-10 keV flux. We find that the true L {sub 2-10keV} estimated from {Gamma}{sub 2-10keV} for the brightest Type Imore » AGNs with z < 1 in the Lockman Hole is generally in agreement with the observed L {sub 2-10keV}. However, there are still many uncertainties, such as the accurate determination of the intrinsic {Gamma}{sub 2-10keV} for distant AGNs and the large uncertainty in the luminosities obtained, which call for significant further study before 'AGN cosmology' can be considered a viable technique.« less
124058283
Dynamical deformation in heavy ion collisions and formation of superheavy nuclei
123628224
Competing fusion and quasifission reaction mechanisms in the production of superheavy nuclei
Within the framework of a dinuclear system model, a new master equation is constructed and solved, which includes the relative distance of nuclei as a new dynamical variable in addition to the mass asymmetry variable so that the nucleon transfer, which leads to fusion and the evolution of the relative distance, which leads to quasifission (QF) are treated simultaneously in a consistent way. The QF mass yields and evaporation residual cross sections to produce superheavy nuclei are systematically investigated under this framework. The results fit the experimental data well. It is shown that the Kramers formula gives results of QF, which agree with those by our diffusion treatment, only if the QF barrier is high enough. Otherwise some large discrepancies occur.
111424651
Ion Transportation Study for Thick Gas Electron Multipliers
Ion back flow(IBF) is defined as the ions that are generated during multiplication in a thick-gas-electron-multiplier (THGEM) detector flow along the electric field. In order to suppress the IBF effect, we study ion transportation for THGEMs with various high voltages and geometrical parameters. By measuring the currents of all the electrodes of the THGEMs, the effective gain and ion back flow ratio are calculated. The measurement and simulation results reveal that with a staggered triple THGEM configuration, ion back flow can be suppressed to 1% with a proper working high voltage. The gain of the staggered configuration is less than that of the aligned configuration by 5% under the same high voltage condition. The design and the results are presented.
118650750
Black hole masses from X-rays
We discuss two methods to estimate black hole (BH) masses using X-ray data only: from the X-ray variability amplitude and from the photon index Gamma. The first method is based on the anti-correlation between BH mass and X-ray variability amplitude. Using a sample of AGN with BH masses from reverberation mapping, we show that this method shows small intrinsic scatter. The second method is based on the correlation between Gamma and both the Eddington ratio L_{bol}/L_{Edd} and the bolometric correction L_{bol}/L_{2-10keV}.