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Liu Z.-H.,China Institute of Atomic Energy | Bao J.-D.,Beijing Normal University | Bao J.-D.,Accelerator Centre
Physical Review C - Nuclear Physics | Year: 2013

Synthesis of element 120 in the 249Cf(50Ti,xn)299-x120 and 248Cm(54Cr,xn)302-x120 fusion evaporation reactions has been evaluated by means of a modified fusion by diffusion model. It is found that the fusion probability of the system 54Cr+248Cm is two times smaller than that of 50Ti+249Cf. On the other hand, the survival probability of the former is obviously greater than that of the latter. As a result, the loss in the fusion probability of the 54Cr+248Cm reaction is compensated by its gain in survival probability. The calculated maximum evaporation residue cross sections in the 249Cf(50Ti,3n)296120 and 248Cm(54Cr,4n)298120 reactions are quite close: 0.034 and 0.024 pb, respectively. Besides, as compared to the system 50Ti+249Cf, the 54Cr+248Cm combination has two advantages. First, 248Cm is much easier accumulate a sufficient amount for the target material than 249Cf. Second, the isotope 298120 has 178 neutrons, two neutrons more than the isotope 296120. Therefore, the 54Cr+248Cm combination should be one of most favorable candidates to produce superheavy element 120. © 2013 American Physical Society.


Wang N.,Guangxi Normal University | Liu M.,Guangxi Normal University | Wu X.,China Institute of Atomic Energy | Meng J.,Beijing University of Technology | Meng J.,Beihang University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

By taking into account the surface diffuseness correction for unstable nuclei, the accuracy of the macroscopic-microscopic mass formula is further improved. The rms deviation with respect to essentially all the available mass data falls to 298 keV, crossing the 0.3 MeV accuracy threshold for the first time within the mean-field framework. Considering the surface effect of the symmetry potential which plays an important role in the evolution of the "neutron skin" toward the "neutron halo" of nuclei approaching the neutron drip line, we obtain an optimal value of the symmetry energy coefficient J = 30.16 MeV. With an accuracy of 258 keV for all the available neutron separation energies and of 237 keV for the α-decay Q-values of super-heavy nuclei, the proposed mass formula is particularly important not only for the reliable description of the r process of nucleosynthesis but also for the study of the synthesis of super-heavy nuclei. © 2014 The Authors.


Xiao X.,University of Chinese Academy of Sciences | Liu X.,University of Chinese Academy of Sciences | Zhao H.,University of Chinese Academy of Sciences | Chen D.,China Institute of Atomic Energy | And 4 more authors.
Advanced Materials | Year: 2012

Co3O4 with three different crystal plane structures - cubes bounded by {001}planes, truncated octahedra enclosed by {111} and {001} planes, and octahedra with exposed {111}planes - is synthesized using a very simple one-step hydrothermal method. The three kinds of Co3O 4 exhibit significantly different electrochemical performances and the effect of different exposed crystal planes on the electrochemical performance of Co3O4 is comprehensively studied. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Zhang Y.,China Institute of Atomic Energy | Tsang M.B.,Michigan State University | Li Z.,China Institute of Atomic Energy | Liu H.,University of Texas at Austin
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

A new version of the improved quantum molecular dynamics model has been developed to include standard Skyrme interactions. Four commonly used Skyrme parameter sets, SLy4, SkI2, SkM* and Gs are adopted in the transport model code to calculate the isospin diffusion observables as well as single and double ratios of transverse emitted nucleons. While isospin diffusion observables are sensitive to the symmetry energy term, they are not very sensitive to the nucleon effective mass splitting parameters in the interactions. Our calculations show that the high energy neutrons and protons and their ratios from reactions at different incident energies provide a robust observable to study the momentum dependence of the symmetry potential which leads to the effective mass splitting. However the sensitivity of effective mass splitting effect on the double n/p yield ratios decreases with increasing beam energy, even though high energy protons and neutrons are produced more abundantly at high beam energy. Our calculations show that the optimum incident energy to study nucleon effective masses is between 100-200 MeV per nucleon. © 2014 The Authors.


Jiang Z.,China Institute of Atomic Energy
Advanced Materials Research | Year: 2013

Radioactive waste minimization is one of the fundamental principles of radioactive waste management, which would reduce the waste volume and activity to the level as low as reasonably achievable. The significance and options of waste minimization methods are reviewed. The nuclear power development and radioactive waste generated in China are summarized. The measures and its function to minimize radioactive wastes and experiences of nuclear power plants (NPPs) in China are analyzed. After Fukushima nuclear accident, China insists on the safety-first principle, reviews its nuclear power development speed. Implementation of waste minimization strategy is an effective and important approach for nuclear power sustainable development. © (2013) Trans Tech Publications, Switzerland.


Dong J.,CAS Lanzhou Institute of Modern Physics | Zuo W.,CAS Lanzhou Institute of Modern Physics | Gu J.,China Institute of Atomic Energy
Physical Review C - Nuclear Physics | Year: 2013

Based on the Skyrme energy density functional, the spatial distribution of the symmetry energy of a finite nucleus is derived in order to examine whether the symmetry energy of a finite nucleus originates from its interior or from its surface. It is found that the surface part of a heavy nucleus contributes dominantly to its symmetry energy compared to its inner part. The symmetry energy coefficient asym(A) is then directly extracted and the ratio of the surface symmetry coefficient to the volume symmetry coefficient κ is estimated. Meanwhile, with the help of experimental alpha-decay energies, a macroscopic method is developed to determine the symmetry energy coefficient of heavy nuclei. The resultant asym(A) is used to analyze the density dependence of the symmetry energy coefficient of nuclear matter around the saturation density, and furthermore, the neutron skin thickness of 208Pb is deduced which is consistent with the pygmy dipole resonance analysis. In addition, it is shown that the ratio κ obtained from the macroscopic method is in agreement with that from the Skyrme energy density functional. Thus the two completely different approaches may validate each other to achieve more compelling results. © 2013 American Physical Society.


Hu Q.-L.,China Institute of Atomic Energy | Gao Z.-C.,China Institute of Atomic Energy | Chen Y.S.,China Institute of Atomic Energy
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

We present new formulae for the matrix elements of one-body and two-body physical operators, which are applicable to arbitrary Hartree-Fock-Bogoliubov wave functions, including those for multi-quasiparticle excitations. The testing calculations show that our formulae may substantially reduce the computational time by several orders of magnitude when applied to many-body quantum system in a large Fock space. © 2014 The Authors.


Zhang Y.,China Institute of Atomic Energy | Tsang M.B.,Michigan State University | Li Z.,China Institute of Atomic Energy
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2015

Using covariance analysis, we quantify the correlations between the interaction parameters in a transport model and the observables commonly used to extract information of the Equation of State of Asymmetric Nuclear Matter in experiments. By simulating 124Sn + 124Sn, 124Sn + 112Sn and 112Sn + 112Sn reactions at beam energies of 50 and 120 MeV per nucleon, we have identified that the nucleon effective mass splitting is most strongly correlated to the neutrons and protons yield ratios with high kinetic energy from central collisions especially at high incident energy. The best observable to determine the slope of the symmetry energy, L, at saturation density is the isospin diffusion observable even though the correlation is not very strong (~0.7). Similar magnitude of correlation but opposite in sign exists for isospin diffusion and nucleon isoscalar effective mass. At 120 MeV/u, the effective mass splitting and the isoscalar effective mass also have opposite correlation for the double n/p and isoscaling p/p yield ratios. By combining data and simulations at different beam energies, it should be possible to place constraints on the slope of symmetry energy (L) and effective mass splitting with reasonable uncertainties. © 2015 The Authors. Published by Elsevier B.V.


Hu H.-C.,China Institute of Atomic Energy
Acta Crystallographica Section A: Foundations of Crystallography | Year: 2010

During the preparation of versatile tables for the secondary extinction factor Yμ of cylindrical and spherical mosaic crystals expressed as functions of the Bragg angle θ, absorption coefficient times radius μ θ and reduced radius τ0 = σ0ρ [σ0 = (2π)1/2Q/η], or of θ, τ0 and ξ0 = μ/σ0, five kinds of Students Tn probability functions T1, T2, T3, T4, T∞ for describing the mosaic distribution of crystals have been tested. T1 is Lorentzian (L) and T∞ is close to Gaussian (G). The influence of these different mosaic distributions upon the reflection power ratio, the integrated reflection power ratio (the area under the rocking curve) and the extinction factor Y μ in cylindrical crystals has been thoroughly investigated. For a weakly absorbing cylindrical crystal with τ0 = 30, the value of Yμ for the T2 distribution turns out to be nearly two times the value for G, but the difference between these distributions becomes small when ξ 0 > 1. The L distribution has been found to be unsuitable for describing the mosaic distribution. The determination of different types of mosaic distribution from the rocking curves is discussed based on these results. Finally T2, T4 and the G distribution have been found to be acceptable for the calculation of secondary extinction factor tables for cylindrical and spherical crystals. © 2010 International Union of Crystallography Printed in Singapore - all rights reserved.


Jia G.,China Institute of Atomic Energy | Jia J.,China Institute of Atomic Energy
Journal of Environmental Radioactivity | Year: 2012

Radium (Ra) isotopes are important from the viewpoints of radiation protection and environmental protection. Their high toxicity has stimulated the continuing interest in methodology research for determination of Ra isotopes in various media. In this paper, the three most routinely used analytical techniques for Ra isotope determination in biological and environmental samples, i.e. low-background γ-spectrometry, liquid scintillation counting and α-spectrometry, were reviewed, with emphasis on new methodological developments in sample preparation, preconcentration, separation, purification, source preparation and measurement techniques. The accuracy, selectivity, traceability, applicability and minimum detectable activity (MDA) of the three techniques were discussed. It was concluded that the MDA (0.1mBqL -1) of the α-spectrometry technique coupled with chemical separation is about two orders of magnitude lower than that of low-background HPGe γ-spectrometry and LSC techniques. Therefore, when maximum sensitivity is required, the α-spectrometry technique remains the first choice. © 2011 Elsevier Ltd.

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