Measurement of the astrophysical S factor for the low energy ^2H（d,γ）^4He reaction

The γ-rays and protons from an Ed = 20 keV deuteron beam incident on a D-Ti target were measured. A branching ratio of the 2H（d,γ）^4He reaction versus the ^2H（d,p）^3H reaction of Гγ/Гp = （1.061 0.34） x 10.7 has been obtained, and the astrophysical S factor of the ^2H（d,γ）He reaction at the center of mass energy Ecm ≈ 7 keV of （6.0±2.4） ×10^6 keV.b was deduced.     

Dibaryon Mass and Width Calculation with Tensor Interaction

The effect of tensor interaction due to gluon and Goldstone boson exchange on the dibaryon mass and decay width has been studied in the framework of the quark delocalization and colour screening model. The effective S-D wave transition interactions induced by gluon and Goldstone boson exchanges decrease quickly with the increasing channel strangeness, and there is no six-quark state in the light flavour world, which can become a bound one by the help of these tensor interactions, except for the deuteron. The K and η meson exchange effect has been shown to be negligible after a short-range truncation in this model approach. The partial D-wave decay widths, from the NΩ state to the AΞ final states of spins 0 and 1, are 20.7 keV and 63.1 keV respectively. This is a very narrow dibaryon resonance, that might be detected in the relativistic heavy ion reaction by the existing RHIC detectors through the reconstruction of the AΞ vertex mass and by the future COMPAS detector at CERNand the FAIR project in Germany.     

Spatial distribution of electron characteristic in argon rf glow discharges

The spatial distributions of the electron density and the mean electron energy of argon radio frequency (rf) glow discharge plasma in a plasma-enhanced chemical vapour deposition (PECVD) system have been investigated using an established movable Langmuir probe. The results indicate that in the axial direction the electron density tends to peak at midway between the two electrodes while the axial variation trend of mean electron energy is different from that of the electron density, the mean electron energy is high near the electrodes. And the mean electron energy near the cathode is much higher than that near the anode. This article focuses on the radial distribution of electron density and mean electron energy. A proposed theoretical model distribution agrees well with the experimental one: the electron density and the mean electron energy both increase from the centre of the glow to the edge of electrodes. This is useful for better understanding the discharge mechanism and searching for a better deposition condition to improve thin film quality.     

Measurement of D(d,p) T Reaction Cross Sections in Sm Metal in Low Energy Region (10≤Ed≤20keV)

To study the screening effect of nuclear reactions in metallic environments, the thick target yields, the cross sections and the experimental S(E) factors of the D(d,p)T reaction have been measured on deuterons implanted in Sm metal at 133.2K for beam energies ranging from 10 to 20keV. The thick target yields of protons emitted in the D(d,p) T reaction are measured and compared with those data extrapolated from cross sections and stopping power data at higher energies. The screening potential in Sm metal at 133.2K is deduced tobe 520±56eV. As compared with the value achieved in the gas target, thecalculated screening potential values are much larger. This screening potential cannot be simply interpreted only by the electron screening. Energy dependences of the cross section σ(E) and the experimental S(E) factor for D(d,p)T reaction in Sm metal at 133.2K are obtained, respectively.     

Measurement of ^2H（^8Li, ^9Be）n Reaction Relevant to Primordial Nucleosynthesis

The angular distribution of the ^2H（^8Li, ^9Be）n （ground state） reaction, important to primordial nucleosynthesis in the inhomogeneous model, has been measured at E = 8.1 MeV using a secondary ^8Li beam. Cross section of this reaction was determined to be 9.0 4±3.4 mb. According to the cross section, the astrophysical S-factor was calculated to be 272 4±103 keV b. It is shown that ^2H（8^Li, ^9Be）n （ground state） reaction is important for creating 9Be, but less important for destroying aLl in primordial nucleosynthesis.     

Measurement of the Breakup Cross Sections in ^6He＋^9Be Reaction at 25 MeV／Nucleon

The breakup reaction cross sections were measured for the reaction of^6He at 25 MeV/nucleon from ^9Be target with intensity of 10^5 pps. By fitting the energy spectra of breakup α particles with Gaussian functions, the angular distribution of differential cross sections in the laboratory system has been extracted and compared with the Serber model calculations. The good agreement between the calculation and the experimental data favours a dominant configuration of the ^4He core plus valence neutrons for the structure of^6He.     

Experimental Evidence of the Rapidly Increasing Neutron Yields in Proton—Induced Reaction on Heavy Target Across 0.6—1 GeV

The independent yield distribution of the Hg isotopes,measured for the reaction of 600MeV ^18O projectile with a ^nat.Pb target,is converted to 18O 208Phb system and is compared with an Hg-isotope distribution from the spallation reaction of 1A GeV^208Pb on proton.The comparison shows the differences between the two distributions on the production cross sections,isotope-distribution widths as well as their shapes.A great increase of the neutron-deficient Hg isotope yield with increase of bombarding energies of protons from 600MeV to 1GeV is derived.This fact results in an experimental evidence for rapid increasing neutron yields with rising proton bombarding energy from 0.6GeV to 1 GeV.     

Computer simulation of symmetrical tilt grain boundaries in noble metals with MAEAM

This paper reports that an atomic scale study of [\bar {1}10] symmetrical tilt grain boundary (STGB) has been made with modified analytical embedded atom method (MAEAM) for 44 planes in three noble metals Au, Ag and Cu. For each metal, the energies of two crystals ideally joined together are unrealistically high due to very short distance between atoms near the grain boundary (GB) plane. A relative slide between grains in the GB plane results in a significant decrease in GB energy and a minimum value is obtained at specific translation distance. The minimum energy of Cu is much higher than that of Ag and Au, while the minimum energy of Ag is slightly higher than that of Au. For all the three metals, the three lowest energies correspond to identical (111), \mbox(113) and \mbox(331) boundary successively for two translations considered; from minimization of GB energy, these boundaries should be preferable in [\bar {1}10] STGB for noble metals. This is consistent with the experimental results. In addition, the minimum energy increases with increasing reciprocal planar coincidence density \Sigma, but decreases with increasing relative interplanar distance d /a.     

Crust-core properties of neutron stars in the Nambu–Jona-Lasinio model

We adopt the Nambu–Jona-Lasinio(NJL) model to study the crust-core transition properties in neutron stars(NSs). For a given momentum cutoff and symmetry energy of saturation density in the NJL model, decreasing the slope of the symmetry energy gives rise to an increase in the crust-core transition density and transition pressure.Given the slope of the symmetry energy at saturation density, the transition density and corresponding transition pressure increase with increasing symmetry energy. The increasing trend between the fraction of the crustal moment of inertia and the slope of symmetry energy at saturation density indicates that a relatively large momentum cutoff of the NJL model is preferred. For a momentum cutoff of 500 Me V, the fraction of the crustal moment of inertia clearly increases with the slope of symmetry energy at saturation density. Thus, at the required fraction(7%) of the crustal moment of inertia, the NJL model with momentum cutoff of 500 Me V and a large slope of the symmetry energy of saturation density can give the upper limit of the mass of the Vela pulsar to be above 1.40 M_⊙.     

Numerical simulation of dispersion generated by a 180° turn in a microchannel

A numerical scheme is developed to simulate electro-osmotic flow and mass transport in a microchannel which includes a 180° turn. The model has been used to predict the behaviour of electro-osmotically driven flows. The detailed structure of the flow field in a microchannel in combination with species mass diffusion can explain the concentration dispersion introduced by a 180° turn. The results of our simulations agree both qualitatively and quantitatively with experimental observation. It is demonstrated that an improved electro-osmotic force model could simulate the electrokinetically driven flow well without making detailed calculations of the electric charge density distribution within the electrical double layer. Additionally, because this model applies forces to the liquid as opposed to imposing local velocities, it should also be appropriate for use where pressure gradients exist in the flow field.     

Density Dependence of the Detailed Spectral Line Effects on the Opacity of Astrophysical Abundant Elements： oxygen

A full relativistic detailed-level-accounting approach has been developed independently to deal with the detailed spectral line effects on the opacity of the third most abundant element in stars: oxygen. The atomic energy levels and the oscillator strengths of the radiative transitions between the energy levels are obtained by carrying out the full relativistic one-configuration Dirac-Fock calculations. The photoionization cross sections are obtained via an average atom scheme with a consideration for the splitting of the ionization threshold due to the ionization stages and the term-couplings. As an example, the spectra resolved opacities and the mean opacities of oxygen are calculated to show the importance of the detailed spectral line profiles with the density of the matter.     

Probability of Field-Aligned Currents Observed by the Satellite Cluster in the Magnetotail

Field-aligned current （FAC） density distribution at the plasma sheet boundary layers is statistically studied. The FAC is calculated by the so-called curlometer technique with the data from FGM onboard the four Cluster spacecraft in 2001. By calculation we obtain a large number of FAC samples. In the samples, most of calculated FAC densities were very small and around zero caused by some errors or noise. In order to get the real FAC density distribution in the magnetotail, we use a three-Gaussian distribution to fit the errors, then subtract the estimated error contribution from the full distribution and obtain the FAC density distribution. The result shows that the FAC occurrence versus its density has a distribution consisting of a Gauss/an distribution with an additional decreasing exponential distribution. The most probable value of the FAC density is 3.45 pT/km.     

One-Proton Halo Structure in ^23Al

The Glauber theory is used to investigate the reaction cross section of proton-rich nucleus ^23Al. A core plus a proton structure is assumed for ^23Al. HO-type density distribution is used for the core while the density distribution for the valence proton is calculated by solving the eigenvalue problem of Woods-Saxon potential The transparency function in an analytical expression is obtained by adopting multi-Gaussian expansion for the density distribution. Coulomb correction and finite-range interaction are introduced. This modified G1auber model is suitable for halo nuclei. A dominate s-wave is suggested for the last proton in ^23Al from our analysis which is possible in the calculation of relativistic mean-field theory.     

Electronic Structures of the Filled Tetrahedral Semiconductor LiMgN with a Zincblende—Type Structure

An ab initio method with mixed-basis norm-conserving non-local pseudo-potentials has been employed to investigate the electronic structures of LiMgN.The band structure ,electronic density of states and charge density contour plot of LiMgN are also presented.By the calculation,we have found that LiMgN with a zincblende-type structure was an indirect gap semiconductor,and the value of indirect(Γ-X) energy band gap under the local density approximation was 2.97eV.In addition,the strong covalent charcter for Li-N and Mg-N has also been found in LiMgN.     

Experimental evidence for temperature ef f ect on energy loss of low-energy D~+ in liquid lithium

In order to investigate the temperature effect on the stopping power of liquid lithium material for keV D+, the excitation functions of the α-particle yields for the6Li(d,α)4He reaction in liquid lithium(495–600 K) have been measured for the bombarding energies from 50 to 70 keV by 2.5 keV steps.The observations show that the thick-target α-yield increases statistically as lithium temperature increases.These phenomena revealed that the only possible reason is a temperature effect on the stopping power, i.e., increasing temperature resulting in a lower stopping power.As the lithium temperature increased from 495 to 600 K, the energy loss of deuterons decreased about 6.7% in the energy region of E 70 keV.     

Determination of astrophysical ~7Be(p,γ)~8B reaction rates from the ~7Li(d,p)~8Li reaction

The7Be(p,γ)8B reaction plays a central role not only in the evaluation of solar neutrino fluxes but also in the evolution of the first stars.Study of this reaction requires the asymptotic normalization coefficient(ANC) for the virtual decay8 Bg.s.→7Be + p.By using the charge symmetry relation,we obtain this proton ANC with the single neutron ANC of8 Lig.s.→7Li + n,which is determined with the distorted wave Born approximation(DWBA) and adiabatic distorted wave approximation(ADWA) analysis of the7Li(d,p)8Li angular distribution.The astrophysical S-factors and reaction rates of the direct capture process in the7Be(p,γ)8B reaction are further deduced at energies of astrophysical relevance.The astrophysical S-factor at zero energy for direct capture,S17(0),is derived to be(19.9±3.5) e V b in good agreement with the most recent recommended value.The contributions of the1+and 3+resonances to the S-factor and reaction rate are also evaluated.The present result demonstrates that the direct capture dominates the7Be(p,γ)8B reaction in the whole temperature range.This work provides an independent examination to the current results of the7Be(p,γ)8B reaction.     

Diagnostics of Atmospheric Pressure Surface Discharge Plasmas in Argon

Atmospheric pressure surface discharge is shown to have great prospects for a number of industrial applications.To acqu/re better results in application fields and considering that the study of the basic parameters includingelectron temperature and electron density is desirable, we develop an equivalent circuit model and the diagnostictechniques based on optical emission spectroscopy and electrical measurement in our laboratory. The electrontemperature has been determined to be about 0.7eV by a Fermi-Dirac model. The electron density has beencalculated to be near 10^10 cm^-3 from a time resolved electrical measurement (Ohmic heating method).     

Numerical investigations on the current conduction in bilayer organic light-emitting devices with ohmic injection of charge carriers

A numerical model for bilayer organic light-emitting diodes (OLEDs) has been developed on the basis of trapped charge limited conduction. The dependences of the current density on the operation voltage, the thickness and trap properties of the hole transport layer (HTL) and emission layer (EML) in bilayer OLEDs of the structure anode/HTL/EML/cathode have been numerically investigated. It has been found that, for given values of reduced trap depth, total trap density, and cv~rrier mobility of HTL and EML, there exists an optimum thickness ratio of HTL to the sum of HTL and EML, by which a maximal current density, and hence maximal quantum efficiency and luminance,can be achieved. The current density decreases quickly with the mean trap density, and decreases nearly exponentially with the mean reduced trap depth.     

Clustering Structure of 10Be Studied with the Deformed RMF＋BCS Method

We investigate the nucleus 10Be using the deformed relativistic mean field （RMF） model and BCS theory. The calculated density distribution suggests two α clusters in the nucleus 10Be. According to BCS theory, the two valence neutrons transit to the first excited state 02＋ in a pair and form a 2-n cluster. By comparing the two neutron separation energy （S2n） with the single neutron separation energy （Sn）, and analyzing the difference between the neutron and proton rms radii （Rn-Rp） calculated by the deformed RMF, we suggest that 10Be is the best candidate for a two-neutron skin. The two-neutron skin clings to the 2α clusters closely and makes the two α clusters have cross and chain distribution.     

A Discharge—Excited SrBr2 Vapour Laser

A new-style discharge tube for a metal vapour laser has been designed and built.SrBr2 was successfully used to replace the metal strontium as a working medium.Multi-line laser oscillations from resonance to metastable transition of strontium atoms (6.45μm),ions (1.03μm/1.09μm) and from strontium ion recombination (416.2nm/430.5 nm)have been obtained through longitudinal pulsed discharge.The problem of an incompatibility reaction between metallic strontium and the discharge tube in the strontium vapour laser has been solved.Some proposals are presented for further developments of strontium halide lasers.