Collective flow in 2.76 and 5.02 A TeV Pb + Pb collisions

In this paper, we study and predict flow observables in 2.76 and 5.02 A TeV Pb + Pb collisions, using the iEBE-VISHNU hybrid model with TRENTo and AMPT initial conditions and with different forms of the QGP transport coefficients. With properly chosen and tuned parameter sets, our model calculations can nicely describe various flow observables in 2.76 A TeV Pb + Pb collisions, as well as the measured flow harmonics of all charged hadrons in 5.02 A TeV Pb + Pb collisions. We also predict other flow observables, including \(v_n(p_T)\) of identified particles, event-by-event \(v_n\) distributions, event-plane correlations, (normalized) symmetric cumulants, non-linear response coefficients and \(p_T\)-dependent factorization ratios, in 5.02 A TeV Pb + Pb collisions. We find many of these observables to remain approximately the same values as the ones in 2.76 A TeV Pb + Pb collisions. Our theoretical studies and predictions could shed light to the experimental investigations in the near future.     

Pb核性质和残余相互作用

在壳模型的框架中,用MSDI和K-H相互作用作为中子空穴间的残余相互作用.计算和讨论了Pb(A=204,205,206)的结构性质;对MSDI和K-H相互作用的结果作了较全面的比较,比较结果表明,MSDI也是一种很好的残余相互作用,可以很好地应用于描述铅区核的性质.另外,还讨论了直接从实验值来检验和判定两体矩阵元的方法.     

158A GeV/c Pb+Pb碰撞可能有QGP的一旁证

用不含QGP假设的强子和弦级联模型(JPCIAE) ,研究了CERNWA98实验组新近发表的158 AGeV/c Pb+Pb中心碰撞中直接光子和π⁰粒子的横动量分布:两者的理论结果均一致的低于实验值.联系到JPCIAE能成功解释无直接光子超出确切迹象的WA80和WA93对200A GeV/c S+Au中心碰撞测量得出的结果:因而为158A GeV/c Pb+Pb中心碰撞中可能有QGP生成提供了一个旁证.     

Pb和Pb合金薄膜隧道结的表面观察及其损坏机理的探讨

对Pb和Pb合金薄膜隧道结的电极薄膜表面进行了观察,并把观察结果同结在低温下的直流I-V特性作了比较,从而进一步肯定了结区电极上的小丘、晶须和微晶粒等显徽结构引起位垒层短路是结热循环损坏的主要原因.     

Pb氯化反应机理的量子化学研究

本文用量子化学从头计算MP2方法,在SDD基组水平上研究了煤燃烧过程中Pb与HCl、 Cl2在高温条件下两个反应的微观机理,通过优化得到反应物、过渡态、中间体和产物的几何构型。在同一水平上计算能量,同时进行零点能校正,并以此能量计算活化能和反应热效应。采用经典过渡态理论计算反应速率常数。计算结果与相关文献进行了比较,结果比较吻合,表明采用量子化学研究铅等痕量元素与气体反应的机理和动力学参数、热力学参数是可行的。     

158GeV/c的Pb–Pb碰撞中的J/ψ抑制现象研究

在Blaizot等人建立的模型基础上,我们考虑了核–核碰撞中的参与者数与核子–核子碰撞数的起伏效应对J/?ψ产生的影响,并对NA50合作组在入射动量为158GeV/c的Pb-Pb碰撞中的实验数据进行了分析,理论结果与实验数据符合的很好     

158A GeV Pb+Pb反应中多粒子产生的双源统计模型分析

提出双源统计模型并用它研究了158A GeV Pb+Pb反应中多粒子产生.模型很好地描述了实验,同时给出一个合理清晰的物理图像.反应系统由一个热而小的内源和一个大而较凉的外源构成.外源具有类弹和类靶特征,内源具有反应中心区特征.在freeze-out时系统仍处于膨胀中.     

Hadron Multiplicities in Pb＋Pb Collisions at the Large Hadron Collider and Pomeron Loop Effects

We study the pseudo-rapidity distribution of hadron multiplicities of high energy Pb＋Pb collisions by using color glass condensate dynamics at LHC/ALICE in the fixed coupling case. It is found that after including the pomeron loop effects the charged hadron multiplicities at central rapidity are about 1500 for central Pb＋Pb collisions, which are significantly smaller than the saturation based calculations, ～ 1700 ÷ 2500 and compatible with that based on a study of multiplicities in the fragmentation region.     

Towards tomography of quark–gluon plasma using double inclusive forward-central jets in Pb–Pb collision

We propose a new framework, merging High Energy Factorization with final-state jet quenching effects due to interactions in a quark–gluon plasma, to compute di-jet rates at mid-rapidity and forward rapidity. It allows one to consistently study the interplay of initial-state effects with medium interactions, opening the possibility for understanding the dynamics of hard probes in heavy-ion collisions and the QGP evolution in rapidity.     

Electrophysical properties of Pb1−xGdxTe

The solid solution system PbTe-GdTe has been investigated. Polycrystalline samples have been formed by the direct synthesis method. Metallographie and X-ray diffractometric analysis was performed. The microhardness was investigated and the Hall coefficient was measured over the temperature range 77–300 K. The experimental results show the donor action of the Gd and that the samples are single phase.     

Pb等离子体电子压强的自洽场计算

对含温有界自洽场平均原子结构中,用分波法和Fermi-Dirac统计处理自由电子.在计算电子压强时考虑了共振态和交换、库仑关联对压强的影响.以Pb为算例,计算了Pb在一些温度密度点下的电子压强,并将计算结果与TF、TFD(Thomas-Fermi-Dirac)等模型作了比较.     

Pb等离子体电子压强的自洽场计算

对含温有界自洽场平均原子结构中，用分波法和Fermi-Dirac统计处理自由电子。在计算电子压强时考虑了共振态和交换、库仑关联对压强的影响。以Pb为算例，计算了Pb在一些温度密度点下的电子压强，并将计算结果与TF、TFD(Thomas-fermi-Disc)等模型作了比较。     

Two-Step Oxidation of Pb（111） Surfaces

We report on a two-step method for oxidation of Pb（111） surfaces, which consists of low temperature （90K） adsorption of 02 and subsequent annealing to room temperature. In situ scanning tunnelling microscopy observation reveals that oxidation of Pb（111） can occur effectively by this method, while direct room temperature adsorption results in no oxidation. Temperature-dependent adsorption behaviour suggests the existence of a precursor state for 02 adsorption on Pb（111） surfaces and can explain the oxidation-resistance of clean Pb（111） surface at room temperature.     

低气压下土壤中Pb等离子体光谱特性

用Nd∶YAG激光诱导激发土壤等离子体,研究了环境压力(在1.01×105与1×102 Pa之间)对土壤等离子体辐射特性及元素检出限的影响。结果表明,随着气压的降低,土壤等离子体的谱线强度、信背比先增大后减小,最高均可达常压下的1.69倍;电子密度同样呈现先增大后减小的趋势,在气压8×104 Pa下达到最大值3.56×1016 cm-3,比常压下高出1.5×1015 cm-3;在气压8×104 Pa下诱导激发等离子体发射光谱与常压下相比有较好的稳定性和较高的精密度。20次重复实验得到土壤等离子体分析线信号强度的相对标准偏差为1.1%,明显低于常压下的3.5%,低气压下稳定性显著提高。应用内标法对自制土壤中Pb元素建立定标曲线,计算得到气压8×104 Pa下土壤中Pb元素的检出限为57.27 mg·kg-1,较常压下降低了39.23 mg·kg-1。表明适当的低压环境可以有效提高LIBS的光谱检测灵敏度,改善元素分析的检出限以及增加光谱定量分析的准确度和精密度。     

Theg-factor of 19− isomer in202Pb

The half-life and the g-factor of the 19^– isomer at (5241.9+) keV in²⁰²Pb have been measured through the in-beam time differential perturbed angular distribution technique as T_1/2=105(2) ns and g(19^–)=0.099(3). The value of the g-factor indicates predominantly four neutron hole configurations involving three i ₁₃ ^2/–1 neutron holes coupled to a f ₅ ^2/–1 neutron hole for the 19^– isomer.     

Fragmentation Cross Sections of 158 AGeV Pb Projectiles

We investigate the fragmentation cross sections of 158 AGeV ^207Pb projectile interacting with different targets using CR39 nuclear track detectors. The exposure is made at SPS beam facility of CERN. The detectors are chemically etched to obtain data in the form of etched cone length. The nuclear and electromagnetic contributions to the measured total charge-changing cross sections are investigated. The estimated results are compared with those found in the literature for similar research work.     

Impurity absorption in indium-doped Pb1−xSnxTe

Optical absorption spectra of indium doped Pb_1−xSn_xTe (x = 0–0.22) have been measured at 90 and 300 K. It was found that doping gives rise to a broad absorption band with its maximum at photon energies much greater than the thermal ionization energy of the indium impurity. The energetic position and the shape of impurity absorption band change little with alloy composition, but the band broadens substantially with temperature. The results are explained by a strong lattice relaxation around the indium impurity.