STAR measurement of system size and incident energy dependence of pt correlations at RHIC

We present the results on measurement of event-by-event p _t fluctuations and correlations for Cu+Cu collisions at ?{s_NN }\sqrt {s_{NN} } = 62.4 and 200 GeV from STAR experiment at RHIC. These results are compared with those from Au+Au collisions at ?{s_NN }\sqrt {s_{NN} } = 62.4 and 200 GeV to study the system size dependence. We find that the dynamical p _t fluctuations are finite and decrease with increasing collision centrality. The p _t correlations are studied as a function of collision centrality and are observed to decrease as we go from peripheral to central collisions. The square root of p _t correlations scaled by mean p _t are observed to be independent of beam energy as well as colliding ion size.     

Orientation dependence of the solid/liquid interfacial free energy in binary systems

A first-order theory of compositional segregation at solid/liquid interfaces, based on a pair-bonded, lattice-liquid interfacial model, has been applied to predict the effect of segregation on the orientation dependence of the interfacial free energy in binary metallic systems. The results show that the sharpness of the cusps in the gamma plot is reduced due to preferential segregation at layer edges as compared to layer faces, and cusps may be eliminated under certain conditions. The reduction in cusp sharpness is the greatest when the composition difference of the solid and liquid phases is large and the solutions are appreciably non-ideal. The relative reduction of sharpness due to segregation is less pronounced for cusps which are sharper in the unsegregated condition, so segregation tends to smooth the form of the gamma plot. Graphical results are presented for calculation of segregational anisotropy effects in general systems.     

Determination of angle dependence of sputtering yield for a multicomponent target by the time characteristics of the sputtering process

A method for determining the variations of sputtering yield of multicomponent target based on studies of time characteristics of the sputtered particles flux has been proposed and tested on an example of the angle dependence of sputtering yield. Time dependences of variation in the fluxes of the sputtered atoms of multicomponent oxides at different incidence angles of Ar ions were studied. Angular dependences of the sputtering yield for these compounds were obtained by direct measurements and computations. It has been shown that the angular dependence of the sputtering yield in a stationary mode can be obtained from the time dependences of the fluxes of the sputtered particles.     

A measurement of direct photon production at large pT at the CERN ISR

We have measured direct photon production in pp collisions at the CERN intersecting storage rings for c.m. energies 31 < √s < 63 GeV and transverse momenta up to 9GeV/c, using segmented lead/liquid-argon calorimeters. The ratio of direct photon to π⁰ production is significantly larger than zero, starting at p_T ≈ 4 GeV/c and increasing to values of about 0.4 at 9GeV/c. No significant √s dependence is seen.     

Anomalous temperature dependence of the energy gap of AgGaS2

The lowest energy gap Eg of AgGaS₂ in the temperature range from 4.2 to 300° K was determined from the reflectivity, photoluminescence and absorption measurements. Below ～ 80° K the temperature coefficient of the energy gap is +6 × 10^-5eV/°K. Above ～80° K the sign of the coefficient reverses and the value is -1.8 × 10^-4eV/°K. The positive value is explained with the lattice dilation effect being the dominant mechanism for the energy gap variation at lower temperatures than ～80°K.     

Temperature and energy dependence of the minimum yield in axial channeling

An analytical expression for the minimum yield in axial channeling is obtained using Lindhard theory for the real situation. The temperature and energy dependence agree well with a Monte-Carlo calculation by Barrett.     

A measurement of the azimuthal angle dependence of the process ep → enπ+ near threshold

The azimuthal angle dependence of the process ep → enπ⁺ has been measured by detecting the electron and neutron in coincidence. Data are presented for momentum transfers (?k²) between 0.08 and 0.32 $\text{(}\text{GeV}\text{c}\text{)}{}^2$ and at energies close to threshold. Fixed-t dispersion relation models give predictionsin good qualitative agreement with the data.     

PS_(3000)-b-PAA_(5000)球形胶束温度效应的原位小角X射线散射技术研究

应用小角X射线散射技术(SAXS)对两亲嵌段共聚物聚苯乙烯聚丙烯酸(PS-b-PAA)胶束形貌的温度影响进行了原位表征.SAXS结果表明:随着水含量的增加,粒子尺寸相应增加;对于水含量10%的PS_(3000)-b-PAA_(5000)胶束溶液,发现了明显的SAXS双峰现象;双峰的位置不随着温度的变化而改变,但是peak 1和peak 2的相对强度随着温度发生了减弱和增强的交错变化;相邻的SAXS双峰说明在PS_(3000)-b-PAA_(5000)胶束溶液中最初形成的粒子尺寸并不是均匀的,主要分为尺寸极其相近的两种球形粒子;随着温度的升高,粒径大小不同的两种粒子存在着一种消融和生长的过程,并且保持着一个相同的归一化动态平衡速率.     

A study of deep inelastic hadron-hadron collisions with a large acceptance calorimeter trigger

Large transverse energy cross sections of 300 GeV/c pions and protons on hydrogen have been measured with a segmented calorimeter covering the central rapidity region ?0.88 < y < 0.67 and 2π in azimuth. The selected events show large multiplicities and no jet-like event structure. Processes more complicated than the scattering of two constituents appear to dominate these inelastic collisions.     

Larmor diffraction measurement of the temperature dependence of lattice constants in CuGeO3

By using the neutron Larmor diffraction method and a setup based on the improved neutron resonant spin echo option ZETA recently installed on the three-axis spectrometer IN22 (CRG beam line at the ILL), we have determined the precise relative evolution of the inter- and intra-chain lattice constants of the paradigmatic spin-Peierls compound CuGeO₃ as a function of temperature. Our results are consistent with previous results obtained by conventional high-resolution diffraction. This method also allows to retrieve independently the sample mosaicities, as well as the widths of various lattice-spacings distributions, thus offering an evaluation of the intrinsic sample quality. In spite of the good definition of the spin-Peierls transition at T_SP=14.1(1) K in our sample, we observe a large distribution of lattice constants (Δd/d?3×10⁻³), while the mosaicity of the sample appears to be quite reasonable (?20′).     

A study of high transverse energy interactions of 150 and 300 GeV pions and protons on a hydrogen target using a large acceptance calorimeter

Interactions of 150 GeV pions and 300 GeV pions and protons on hydrogen which result in final states with large transverse energy in the central rapidity region ?0.88 < y < 0.67 were studied with a calorimeter trigger. The dependence of the cross section on the azimuthal acceptance of the trigger, on the beam energy and on the incident particle type and the jet properties of the events were investigated. No dominant two-jet structure was found. Nevertheless, the parton spectrum in the colliding hadrons appears to be relevant for large transverse energy reactions.     

Visualized measurement of the electric field in large aperture LiNbO3 crystal by digital holographic interferometry

The electric field distribution in Li Nb O3 crystal under different electrode shape is presented by using the digital holographic interferometry. Three configurations of phase modulator including the rectangular electrode type,single-triangle electrode type, and dual-triangle electrode type are performed in this experiment. The nonuniform electric field distribution in these phase modulators are observed and the electric field increases with voltage increasing. The digital holographic interferometry with high electro-optic effect improves the measurement precision. The digital holographic interferometry provides an effective way for studying the electric field distribution. Such in situ quantitative analysis of electric field distribution is a key to optimizing electrode shape.     

Hole concentration dependence of Mn eg orbital state in bilayer manganites studied by magnetic Compton profile measurement

Magnetic Compton profiles (MCP) have been measured in the [100], [110] and [001] directions on the single crystals of La_2−2xSr_1+2xMn₂O₇ (x=0.30, 0.35 and 0.42) at 10 K. The occupation numbers in t_2g and two e_g type orbitals (x²−y² and 3z²−r²) of Mn-3d state are evaluated from the line-shape analysis of MCP's in the [001] direction by using theoretical profiles derived from the ab initio calculations for (MnO₆)⁸⁻cluster. It has been found that the e_g state is dominated by the x²−y² type orbital at every hole concentration, x, and the 3z²−r² type orbital population decreases with increasing x. From the result, the connections of e_g orbital state with the electron correlation effect, exchange interactions, lattice distortion and electronic inhomogeneity are discussed.     

Nuclear mass number dependence of inclusive pion production by pions and protons at 4.3GeV/c

The inclusive production of π⁺ for 0.4≤p_T<1.0 GeV/c in pion-nucleus and proton-nucleus collisions at 4.3 GeV/c was measured. A strong A-dependence of the cross sections at high p_T is observed to be persistent in the low energy region. The ratio of the cross sections for proton-nucleus and pion-nucleus collisions is also observed to be compatible with the quark-parton picture, for p_T>0.6 GeV/c.     

Temperature dependence of the Urbach energy in ordered defect compounds Cu-III3-VI5 and Cu-III5-VI8

Two previous models used with success in Cu-III-VI₂ semiconductors have been employed to study the temperature dependence of the Urbach energy in ordered compounds Cu-III₃-VI₅ and Cu-III₅-VI₈. The model which contains two variable parameters seems to explain better the data over the whole temperature range studied. However, the ordered vacancy or the donor acceptor defect pair in the cation sublattice provides new features in these compounds that need further study.     

Frequency dependence of the spin-lattice relaxation time in solid H2 with very low concentration of ortho-molecules

By extending the previous theory of Hama et al. for the spectral density in the system of randomly distributed spins with R^–n-interactions, the frequency dependence of the spin-lattice relaxation time of o-H₂ in solid H₂ at very low concentration is studied, with results in excellent agreement with measurements. In the present extension the effects of the anisotropy and rotational Zeeman energies have been taken into account by the use of the measured constants relevant to both energies.     

Controlling energy deposition during the C60 bombardment of silicon: The effect of incident angle geometry

The profile of the energy deposition footprint is controlled during the C₆₀⁺ erosion of Si surfaces by varying the incident energy and/or incident angle geometry. Sputter yield, surface topography, and chemical composition of the eroded surfaces were characterized using atomic force microscopy (AFM) and secondary ion mass spectrometry (SIMS). The experiments show that the 10 keV, 40° incident C₆₀⁺ erosion of Si results in the formation of a C containing, mound-like structure on the solid surface. We find that the occurrence of this C feature can be avoided by increasing the incident energy of the C₆₀⁺ projectile or by increasing the incident angle of the C₆₀⁺ projectile. While both strategies allow for the Si samples to be eroded, the occurrence of topographical roughening limits the usefulness of C₆₀⁺ in ultra-high resolution semiconductor depth profiling. Moreover, we find that the relative effect of changing the incident angle geometry of the C₆₀⁺ projectile on the profile of the energy deposition footprint, and thus the sputter yield, changes according to the kinetic energy of the projectile and the material of the bombarded surface, a behavior that is quite different than what is observed for an atomic counterpart.