Angular distributions of muon pairs produced by negative pions on deuterium and tungsten

We present the angular distributions of high-mass muon pairs produced in a high-statistics experiment by 140 and 194 GeV/c π^? beams impinging on a tungsten target, and by 286 GeV/c π^? beam on deuterium and tungsten targets. We find no evidence for a center-of-mass energy dependence or a nuclear dependence of the angular distribution parameters. The two parameters λ and μ are found to be essentially independent of any kinematical variable. In contrast, the parameterv increase with the dimuon transverse momentumP _T , at variance with recent perturbative QCD predictions. Our statistics at largex ₁ are insufficient to substantiate the highertwist prediction.     

Bose-Einstein correlations inK + p and π+ p at 250 GeV/c

Two-pion correlations are studied for pions of like charge inK ⁺ p andπ ⁺ p collisions at 250 GeV/c. An enhanced production is observed at small momentum difference and is attributed to Bose-Einstein interference between identical particles. A systematic study is presented on the influence of parametrization and reference sample. Interpreted in terms of the Kopylov-Podgoretskii parametrization a size of the emitting regionr _K ≈1.4 fm is found. The Lorentz invariant parametrization of Goldhaber givesr _G ≈0.8 fm. With fixed parametrization, similarity is found for hadronhadron,e ⁺ e ^? and lepton-hadron collisions. No multiplicity or angular dependence is found at our energy.     

Neutral kaon production inK + p and π+ p interactions at 250 GeV/c

The inclusive production of neutral kaons is studied inK ⁺ p and π⁺ p interactions at 250 GeV/c. Total and semi-inclusive cross sections and average kaon multiplicities are presented and compared with the data at lower energies. The longitudinal and transverse momentum distributions and their energy dependence are analyzed. The results are interpreted in the framework of recent parton models.     

ExperimentalJ/ψ hadronic production from 150 to 280 GeV/c

A detailed study ofJ/ψ hadronic production has been performed in a high statistics experiment (more than 1.5 10⁶ J/ψ observed in their dimuon decay mode). Data have been taken with incident π^±,K ^±,p ^±, on hydrogen and platinum targets, at 150, 200 and 280 GeV/c. We find from the observed nuclear dependance of the cross sections, that about 18% of theJ/ψ are produced diffractively. Using known structure functions of the quarks in the nucleon and in the pion, we derive estimations for the gluon structure functions.     

Charmonium production and nuclear absorption in p-A interactions at 450 GeV

The production of and charmonium states in proton-nucleus interactions has been investigated by the NA50 experiment, at the CERN SPS. High statistics data sets were collected with collisions induced by 450 GeV protons incident on Be, Al, Cu, Ag and W targets. The and production cross-sections have been determined for each p-A system and their dependences on the nucleus size have been studied, leading to the so-called normal nuclear absorption. Comparing the two patterns we see that the nuclear absorption is stronger for the than for the . Given the high statistics of the data samples, the (or rapidity) differential cross-sections of the and states have also been studied, for each of the target nuclei.Received: 23 September 2003, Revised: 29 November 2003, Published online: 29 January 2004     

"电场生物学效应"引入大学物理实验教学的探讨

为培养学生创新意识和能力,实现物理实验教学现代化,本文介绍了将“电场生物学效应”科研工作中取得的部分成果引入大学物理实验教学的一些尝试。     

Annihilation and topological cross sections forpp and\bar p p interactions at 200 GeV/c

The results of an analysis of streamer chamber data from the NA5 experiment are presented. Topological cross sections forpp and \(\bar p\) p interactions and strange neutral particle production at 200 GeV/c have been measured and ( \(\bar p\) p?pp) difference cross sections have been determined. Multiplicity moments were calculated.     

单分子磁体[Mn4(CF3COO)4(hmp)6]的合成、晶体结构及磁学性质

以[Mn12O12(CF3COO)16(H2O)4]·2CF3COOH·4H2O和2-羟甲基吡啶(hmpH)为起始物, 在四氢呋喃溶液中合成了一种新的四核锰配合物[Mn4(CF3COO)4(hmp)6]. X射线单晶衍射结果表明, 该配合物属于单斜晶系, P21/c空间群, 晶胞参数a=1.3663(3) nm, b=1.4705(3) nm, c=1.4734(3) nm, β=98.51(3) °, V=2.9276 nm3, Z=2. 配合物中有两个CF3COO-基团与七配位Mn2中心相连, 其中一个为单齿配体, 另一个是双齿配体. 直流磁化率研究结果表明, 该配合物具有较高的自旋基态, 而交流磁化率依赖于外场频率变化极值的出现表明该配合物是一种单分子磁体.     

新型含联苯结构的酚氧树脂的性能研究

摘要在催化剂和分散剂存在的条件下, 用3,3′,5,5′-四甲基-4,4′-联苯二酚和环氧氯丙烷缩聚, 合成一种新的含联苯结构的酚氧树脂. 用红外光谱, 核磁共振氢谱, 热失重分析仪, 动态力学分析仪和电子拉力机对聚合物进行了分析和性能研究. 结果表明, 这种新型酚氧树脂在热性能方面比双酚A型酚氧树脂有较大提高.