相对论重离子碰撞中的线性背景与非线性效应

系统分析了p-A,¹⁶O-A和³²S-A过程快度分布的靶核依赖性.指出:将核子-核,核-核碰撞看成核子-核子碰撞的线性叠加的几何模型只能得到靶核指数α(η) 0.4.靶核碎裂区α(η)→1的实验数据表明,目前能量下的高能重离子碰撞中,非线性效应已不可忽略.流体动力学模型计算的结果能很好地描述不同射弹过程的靶核依赖性.     

A generalized formulation for the refractive index at the geometric-optics limit

Starting from the concept of rapidity considered as generalization of the group velocity, we establish a generalized mathematical expression for the refractive group index of a material medium with little refraction at sufficiently small wavelengths, this index becoming approximately the refractive index at the geometric-optics limit and the phase velocity being approximately equal to the group velocity at the above limit. As main result, we derive an approximate relationship for the refractive index of a medium of small refraction at the geometric-optics limit. This medium is found to be left-handed at sufficiently small wavelengths.     

Some features of scattering problem in a κ‐Deformed minkowski spacetime

The doubly special relativity (DSR) theories are suggested in order to incorporate an observer‐independent length scale in special theory of relativity. The Magueijo‐Smolin proposal of DSR is realizable through a particular form of the noncommutative (NC) spacetime (known as κ‐Minkowski spacetime) in which the Lorentz symmetry is preserved. In this framework, the NC parameter κ provides the origin of natural cutoff energy scale. Using a nonlinear deformed relativistic dispersion relation along with the Lorentz transformations, we investigate some phenomenological facets of two‐body collision problem (without creation of new particles) in a κ‐Minkowski spacetime. By treating an elastic scattering problem, we study effects of the Planck scale energy cutoff on some relativistic kinematical properties of this scattering problem. The results are challenging in the sense that as soon as one turns on the κ‐spacetime extension, the nature of the two‐body collision alters from elastic to inelastic one. It is shown also that a significant kinematical variable involving in heavy ion collisions, the rapidity, is not essentially an additive quantity under a sequence of the nonlinear representation of the Lorentz transformations.

     

理想气体模型中粒子的快度与赝快度分布

本文通过两种不同的计算快度与赝快度的方法，研究了理想气体模型中粒子的快度与赝快度分布，并对两种计算方法得到的结果进行了比较，发现所给结果相同．本文还研究了在发射源静止系和运动系中粒子快度随发射源温度的变化规律．     

Determination of phenylalanine in blood by high-performance anion-exchange chromatography–pulsed amperometric detection to diagnose phenylketonuria

We have developed a high-performance anion-exchange chromatography with pulsed amperometric detection method for the detection of phenylalanine (Phe) and diagnosis of phenylketonuria (PKU). Sample pretreatment steps were simplified without derivatization. The analyte was separated within 5 min. The detection limit (S/N = 3) for Phe was 50 pg. Linear dynamic range was 1.23–14.43 mg/dL (r² = 0.9999) for a dried blood spot. The mean recoveries of Phe for intra- and inter-day assays were found to be 96.87–104.16%. This method clearly differentiated PKU-positive groups from normal groups, and proved to be a practical procedure for rapid screening and follow-up monitoring of PKU.     

On nuclear stopping in asymmetric colliding nuclei

Using the isospin-dependent quantum molecular dynamics (IQMD) model, nuclear stopping is analyzed in asymmetric colliding channels by keeping the total reacting mass fixed. The calculations have been performed by varying the mass asymmetry of the colliding pairs with different neutron-proton ratios at an incident beam energy of 250 MeV/nucleon. We find sizable effects of mass asymmetry on nuclear stopping and on the equilibrium of the nuclear matter. A reasonable agreement is also observed between the experimental data and our present calculations.