Directed flow of isospin sensitive fragments within a modified clusterization algorithm in heavy-ion collisions

By extending the minimum spanning tree （MST） clusterization algorithm for the binding energy cut, the isospin asymmetry dependence of directed flow for isospin sensitive isobar pairs （neutrons-protons, 3H-3He） is studied from low towards high incident energies. The modified clusterization method （MSTB） has the advantage to identify the fragments at quite early time. It enhances （reduces） the production of free nucleons （fragments） over MST method. The directed flow of isobaric pair 3H-3He is more sensitive towards isospin asymmetry caused by MSTB than isobaric pair n-p. This sensitivity becomes quite strong towards the high incident energy and neutron-rich reaction system. In conclusion, the inclusion of binding energy in clusterization method for the flow studies has been uniquely important for understanding the isospin physics, especially for high density behavior of symmetry energy.     

Isospin splitting of nucleon effective mass and isospin effect in heavy-ion collisions

Two different isospin splittings of nucleon effective mass in nuclear medium as the form of mn〉 mp and mn 〈 mp have been implemented in an isospin and momentum dependent transport model. Their impacts on the isospin emission in heavy-ion collisions is investigated thoroughly. It is found that the yield ratios of energetic neutrons to protons squeezed out during the compression stage of two colliding nuclides are sensitive to the isospin splitting. The elliptic flows of free nucleons are also to be promising observables for extracting the nucleon effective mass splitting. Further experimental measurements are being expected, in particular at the CSR-CEE platform in Lanzhou. Several observables are proposed for constraining the density dependence of symmetry energy, such as the transverse flow difference of neutrons and protons, double ratios ofn/p and π-/π＋, excitation functions of π-/π＋ and K0/K＋.     

Density functional theory study of H,C and 0 chemisorption on UN（O01） and （111） surfaces

We performed density functional theory calculations of H, C, and O chemisorption on the UN（001） and （111） surfaces using the generalized gradient approximation （GGA） and the Hubbard U parameter and revised Perdew-Burke-Ernzerhof （RPBE） exchange-correlation functional at non-spin polarized level with the periodic slab model. Chemisorption energies vs. distance of molecules from UN（001） and UN（111） surfaces have been optimized for four symmetrical chemisorption sites, respectively. The results show that the Hollow, N-top, and Hollow adsorption sites are the most stable sites for H, C, and O atoms with chemisorption energies of 13.06, 25.50 and 27.34 kJ/mol for UN（001 ） surface, respectively. From the point of adsorbent （UN（001） and UN（111） surfaces in this paper）, interaction of O with the chemisorbed surface is of the maximum magnitude, then C and H, which are in agreement with electronegativities of individual atoms. For the UN（001） surface, U-N bond lengths change relatively little （〈 9%） as a result of H chemisorption, however C and O chemisorptions result in remarkable changes for U-N bond lengths in interlayer （〉 10%）. Electronic structure calculations indicate that Bridge position is equivalent with Hollow position, and the most stable chemisorption position for H, C, and O atoms are all Bridge （or Hollow） position for the UN（1 11） surface. Calculated electronic density of states （DOSs） demonstrate electronic charge transfer between .9, p orbitals in chemisorbed atoms and U 6d, 5f orbitals.     

Improvement of digital S-K filter and its application in nuclear signal processing

On the basis of preliminary studies, a novel duo-parameter model consisting of amplitude filter factor and frequency filter factor for low-pass S-K filter is presented in this paper. The model is established by applying numerical differentiation method. Some simulation experiments and real data tests are carried out to verify the feasibility and superiority of the new algorithm. The results show that this duo-parameter model of low-pass S-K filter can be used to achieve high performance in signal processing and nuclear spectrum smoothing.     

Apparent softening of the symmetry energy with the inclusion of non-nucleonic components in nuclear matter

Apparent softening of the symmetry energy with the inclusion of hyperon and quark degrees of freedom is demonstrated by the fact that the phase transition causes the change of the interaction and the suppression of nucleon fractions. The demonstration is fulfilled in the relativistic mean-field model.     

Comparison between nuclear thermometers in central Xe＋Sn collision

The temperature of fragmenting source in central heavy-ion collisions at Fermi energy is investigated by the isospin-dependent quantum molecular dynamics model in combination with the statistical decay model GEMINI. Five different nuclear thermometers are used to extract nuclear temperature. We find that the He and Li isotope temperature reaches a plateau at about 70-100 MeV/nucleon of beam energy. The slope temperature and the quadrupole fluctuation temperature give high values. The quantum slope temperature and the quantum quadrupole fluctuation temperature are more close to the He and Li isotope temperatures.     

Two-proton sequential decay from excited states of 18Ne

Two-proton radioactivity from 18Ne is discussed in terms of sequential decay. The branch ratios for one- proton emission from excited states are calculated, which including spectroscopic factors, obtained from a Shell- model calculation with realistic interactions. The branch ratios show that the two-proton emission from the 1 state of 16Ne at 7.94 MeV is most likely to go through the sequential decay. The same mechanism is discussed for other excited states at higher energy by different interactions.     

Probing the density dependence of the symmetry energy with central heavy ion collisions

An improved isospin dependent Boltzmann Langevin model, in which the inelastic channels and momentum dependent interactions are incorporated, is used to investigate the high-density behavior of nuclear symmetry energy. By taking several forms of nuclear symmetry energy, we calculate the time evolutions of neutron over proton ratio, π ultiplicity and π-/π＋ ratio, and the kinetic energy and transverse momentum spectra of π-/π＋ ratio in the heavy ion collisions at 400A MeV. It is found that the neutron over proton ratio and π-/π＋ ratio are very sensitive to the nuclear symmetry energy, and the π- is more sensitive to the nuclear symmetry energy than the π＋. A supersoft symmetry energy results in a larger π-/π＋ ratio.     

Density isomer of nuclear matter in an equivalent mass approach

The equation of state of symmetric nuclear matter is studied with an equivalent mass model. The equivalent mass of a nucleon has been expanded to order 4 in density. We first determine the first-order expansion coefficient in the quantum hadron dynamics, then calculate the coefficients of the second to fourth order for the given binding energy and incompressibility at the normal nuclear saturation density. It is found that there appears a density isomeric state if the incompressibility is smaller than a critical value. The model dependence of the conclusion has also been checked by varying the first-order coefficient.     

Spallation reaction and the probe of nuclear dissipation with excitation energy at scission

We study in the framework of the Langevin model the influence of initial excitation energy （E＊） of Hg compound nuclei （CNs） on the sensitivity of the excitation energy at scission （E~c） to the nuclear friction strength （fl）. It is shown that the sensitivity is enhanced substantially with increasing E＊. Moreover, we find that the significant sensitivity of E＊c to fl at high E＊ is little affected by a marked difference in the neutron-to-proton ratio ofa CN and in its size and fissility. Our findings suggest that, on the experimental side, a measurement of E~c in energetic proton-induced spallation reactions can provide not only a sensitive but also a robust probe of nuclear dissipation in fission of highly excited nuclei. Further development of a suitable approach to spallation reaction is discussed.     

Collimated LaBr3 detector response function in radioactivity analysis of nuclear waste drums

The properties of a Lanthanum bromide （LaBr3） detector and its response functions were investigated via experiments and simulations in this paper. The LaBr3 detector had good relative energy resolution and higher efficiency than a high-purity germanium detector. Monte Carlo and other numerical methods were used to calculate the efficiencies of a LaBr3 detector with a square collimation window. A model of the numerical method was established based on a pure geometric model that was consistent with the experimental situation. The results showed that the detector response functions calculated by these methods were in great agreement with experimental results.     

On ring and bubble formations in heavy ion collisions

The work is devoted to the implementation of the hydrodynamic laws to the head-on heavy ion collisions within the energy range 50-100 MeV/A. The hydrodynamic mechanisms of the bubble and ring structures formation are investigated. It is shown that there is a possible hydrodynamic explanation of the different structures being formed in the case of soft （K=200 MeV） and stiff （K=400 MeV） equations of state. Within the suggested approach the final geometry of the system is defined in the initial stage of the collision and is very dependent on the sound velocity in the nuclear matter. The obtained results are in a good correspondence with the Boltzmann-like transport theory calculations and the experimental data for the selected energy range.     

Nuclear symmetry energy from QCD sum rules

We calculated the nucleon self-energies in iso-spin asymmetric nuclear matter and obtained the nuclear symmetry energy by taking difference of these of neutron and proton. We find that the scalar （vector） self-energy part gives a negative （positive） contribution to the nuclear symmetry energy, consistent with the result from relativistic mean-field theories. Also, we found exact four-quark operator product expansion for nucleon sum rule. Among them, twist-4 matrix elements which can be extracted from deep inelastic scattering experiment constitute an essential part in the origin of the nuclear symmetry energy from QCD. Our result also extends early success of QCD sum rule in the symmetric nuclear matter to the asymmetric nuclear matter.     

Development of Data Acquisition Card Driver for ICRH System on EAST

Presented in this paper is the development of the driver for the data acquisition card with a peripheral component interconnection （PCI） local bus on the ion cyclotron range of frequency heating （1CRH） system. The driver is mainly aimed at the embedded VxWorks system （real-time operating system） which is widely used in various fields of real-time systems. An efficient way is employed to develop this driver, which will advance the real-time control of the ICRH system on the experimental advanced superconductor tokamak （EAST）. The driver is designed using the TORNADO integrated development environment （IDE）, and implemented in C plus language. The details include the hardware configuration, analogue/digital （A/D） and digital/analogue （D/A） conversion, input and output （I/O） operation of the driver to support over five cards. The data acquisition card can be manipulated in a low-level program and meet the requirements of A/D conversion and D/A outputs.     

Role of Ion Beam Irradiation and Annealing Effect on the Deposition of AlON Nanolayers by Using Plasma Focus Device

AlON nanolayers are synthesized on Al substrate by the irradiation of energetic nitrogen ions using plasma focusing. Samples are exposed to multiple （5, 10, 15, 20 and 25） focus shots. Ion energy and ion number density range from 80 keV to 1.4 MeV and 5.6×10^19 m^- 3 to 1.3×10^19 m ^-3, respectively. Moreover, the effect of continuous annealing （473 K and 523 K） on an AlN surface layer synthesized with 25 focus shots is also examined. The main features of the X-ray diffraction （XRD） patterns with increasing focus shots are： （i） variation in the crystallinity of AlN along （111）, （200） and （311） planes, （ii） increasing average crystallite size of AlN （111） plane, and （iii） stress relaxation observed in AlN （111） and （200） planes. The crystallinity of AlN surface layer is comparatively better at 473 K annealing temperature. A broadened diffraction peak related to an aluminium oxide phase showing weak crystallinity is observed for 15 focus shots while non-bounded oxides are present in all other deposited layers. Raman and Fourier transform infrared spectroscopy （FTIR） analysis confirm the presence of AlN and Al203 for the surface layer annealed at 473 K temperature. Raman analysis shows that the overlapping of AlN and Al2Oa results in the development of residual stresses. Scanning electron microscope （SEM） results demonstrate that the formation of rounded grains （range from 20 nm to 200 nm） and variations in their microstructures features depend on the increasing number of focus shots. Decomposition of larger clusters into smaller ones is observed.     

Simultaneous Oxidization of NOx and SO2 by a New Non-thermal Plasma Reactor Enhanced by Catalyst and Additive

The non-thermal plasma as one of the most promising technologies for removing NOx and SO2 has attrm~ted much attention. In this study, a new plasma reactor combined with catalyst and additive was developed to effectively oxidize and remove NOx and SO2 in the flue gas. The experimental results showed that TiO2 could improve the oxidation efficiency of SO2 in the case of applying plasma while having a negative effect on the oxidation process of NO and NOx. With the addition of NH3, the oxidation rates of NOx, NO and SO2 were slightly increased. However, the effect of adding NH3 on NOx oxidation was negative when the temperature was above 200℃.     

Effect of Cold Plasma Treatment on Seed Germination and Growth of Wheat简

This study investigated the effect of cold helium plasma treatment on seed germina- tion, growth and yield of wheat. The effects of different power of cold plasma on the germination of treated wheat seeds were studied. We found that the treatment of 80 W could significantly improve seed germination potential （6.0%） and germination rate （6.7%） compared to the control group. Field experiments were carried out for wheat seeds treated with 80 W cold plasma. Com- pared with the control, plant height （20.3%）, root length （9.0%） and fresh weight （21.8%） were improved significantly at seedling stage. At booting stage, plant height, root length, fresh weight, stem diameter, leaf area and leaf thickness of the treated plant were respectively increased by 21.8%, 11.0%, 7.0%, 9.0%, 13.0% and 25.5%. At the same time, the chlorophyll content （9.8%）, nitrogen （10.0%） and moisture content （10.0%） were higher than those of the control, indicating that cold plasma treatment could promote the growth of wheat. The yield of treated wheat was 7.55 t-ha-1, 5.89% more than that of the control. Therefore, our results show that cold plasma has important application prospects for increasing wheat yield.     

Simulation of Electron-Beam Generating Plasma at Atmospheric Pressure

As electron-beam generating plasma is widely applied, the software tool EGS4 （Electron-Gamma Shower） was used to simulate the transmission and energy deposition of electron-beam in air. The simulation results indicated that the range of the electron-beam was inversely proportional to the gas pressure in a wide range of gas pressure, and the electron-beam of 200 keV could generate a plasma with a density 10^11 cm^-3 in air of latm. In addition, the energy distribution of the beam-electron and plasma density profile produced by the beam were achieved.     

Mechanical Properties of Thermoplastic Polyurethanes Laminated Glass Treated by Acid Etching Combined with Cold Plasma

To overcome the problem of interlaminar delamination of thermoplastic polyurethane laminated glass, silicate glass was etched with hydrofluoric acid and thermoplastic polyurethane was then treated with cold plasma. Compared with the untreated samples, the interlaminar shear strength of acid etching samples, cold plasma-treated samples and acid etching combined with cold plasma-treated samples increased by 97%, 84% and 341%, respectively. Acid etching combined with cold plasma-treated samples exhibited a higher flexural strength and strain as compared with the untreated samples. The impact energy of acid etching samples, cold plasmatreated samples and acid etching combined with cold plasma-treated samples increased by 8.7%, 8.1% and 11.6%, respectively, in comparison with the untreated samples. FT-IR analysis showed that a large number of -C-O, CO N and CO O C groups appeared on the surface of cold plasma-treated thermoplastic polyurethane, which resulted in the formation of hydrogen bonds. SEM results showed that some pittings formed on the surface of the silicate glass treated by acid etching, which resulted in the formation of a three-dimensional interface structure between tile silicate glass and polyurethane. Hydrogen bonds combined with the three-dimensional interface between silicate glass and polyurethanes co-improved the mechanical properties of thermoplastic polyurethanes laminated glass.     

Density and temperature of fermions and bosons from quantum fluctuations

A novel method to determine the density and temperature of a system constituted by fermions and/or bosons is proposed based on quantum fluctuations. For fermions system, the results in the limit where the reached temperature T is small and where there is no constraint for the reached temperature T compared to the Fermi energy ~f at a given density p are given, respectively. Quadrupole and multiplicity fluctuation relations are derived in terms of T/6f. We compared the two set results in the limit when Tis much smaller compared to Fermi energy Cf and they are consistent, as expected. The classical limit is also obtained for high temperatures and low densities. For bosons system, quadrupole and multiplicity fluctuations using Landau＇s theory of fluctuations near the critical point for a Bose-Einstein condensate （BEC） at a given density p are derived. As an example, we apply our approach to heavy ion collisions using the Constrained Molecular Dynamics model （CoMD） which includes the fermionic statistics. The multiplicity fluctuation quenching for fermions is found in the model and confirmed by experimental data. To reproduce the available experimental data better, we propose a modification of the collision term in the approach to include the possibility of ct-a collisions. The relevant Bose-Einstein factor in the collision term is properly taken into account. This approach increases the yields of bosons relative to fermions closer to data. Boson fluctuations become larger than one as expected.