Al~(10+)的电子碰撞电离及有关过程

用扭曲波方法计算Al~(10+)基态在Is~22s的Is,2s电子和第一激发态Is~22p的2p电子的电离截面以及基态的总电离截面(包括内壳层激发自电离).入射电子能量(?)(即(?)以2s电离能I_(2s)为单位)为1.05,1.125,l.25,1.5,2.25,4……同时计算出了电离阈值以下的激发截面(乘以所谓态密度),实现了在电离阈值处与阈值以上电离能量微分截面光滑联接;计算了光电离截面积分值,实现了在入射电子能量趋于无穷时与电子碰撞电离截面衔接.计算结果与其他方法进行了比较. 关键词：     

金纳米粒子比色探针检测牛奶及鸡蛋中的三聚氰胺

三聚氰胺能诱导金纳米粒子(AuNPs)团聚,溶液颜色由酒红色变为紫色或蓝灰色.以AuNPs作为比色探针,建立了快速检测牛奶和鸡蛋中三聚氰胺的方法.实验优化得最佳反应条件为:AuNPs粒径13 min、pH=7、反应时间10 min和温度为室温.对样品中常见物质进行了干扰实验.样品经10％三氯乙酸和氯仿提取、离心分离后可直接测定,本方法对牛奶和鸡蛋中三聚氰胺的检出限分别为0.1和2.5 mg/L(S/N=3),加标回收率分别为95.0％～105.0％和98.0％～104.0％.     

GENERATION OF RADICAL CATIONS——A FACILE GENERATION OF RADICAL CATIONS VIA THE ACTION OF AN OXOAMMONIUM TRIFLUOROACETATE

The reaction between a stable nitroxide, 2, 2, 6, 6-tetramethyl-4-chloropiperidinyl-1-oxy, la and aromatic amines and heterocycles, 3—9, in methylene chloride in the presence of trifluoroacetic acid, has been investigated. The corresponding radical cations of the amines and the heterocycles were readily generated by this reaction, which could persist for a long period of time in the system. Kinetic ESR studies were performed to elucidate the reaction mechanism and the results showed that the formation of the radical cations involves one-electron transfer reaction between the active oxidant, the oxoammonium trifluoroacetare, 2a, which results from the disproportionation of the nitroxide in the presence of trifluoroacetic acid, and the substrates studied. This affords a facile method for the generation of radical cations from aromatic amines and heterocyclics by the action of an organic oxidant.     

Angular Distributions for

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Diquark Structure of Pentaquark in the Quark Delocalization Colour Screening Model

In the framework of quark-delocalization, colour-screening model, the diquark structure of pentaquark θ^＋ is studied in detail under the adiabatic approximation. The calculation is carried out by using the fractional parentage expansion technique, which greatly simplify the calculation of the matrix elements of Hamiltonian. The results show that the ground state of the pentaquark has negative parity rather than positive parity, which was proposed by daffe-Wilczek. However the mass obtained is about 1651 MeV which is still higher than the observed mass 1540 MeV.     

Study of (∧) decay parameter in J/ψ→∧(∧)decay

The helicity amplitudes fot J/ψ→∧(∧)and the relevant background decays are presented for measuring the A decay parameter α+((∧)→(p)π)in J/ψ→∧(∧).The Monte Carlo(MC)simulations based on the helicity amplitudes information are carried out.The likelihood fit method to determine the A decay parameter is presented.Based on the MC generated sample,the sensitivity of the measurement for α+has been estimated,which shows that the J/ψ→∧(∧) channel can be used to measure the A decay parameter α+((∧)→(p)π+)well.     

Υ(1S)的强衰变及粲重子结构的研究

在微拢QCD框架内,利用重子结构的夸克模型,计算了Υ→pp,ΛcΛc,∑c∑-c,ΞcΞc,Ξ ccΞ-cc,ΩcccΩccc衰变的分支比,讨论了在Υ衰变中寻找Ωccc粲重子的可能性.     

Track reconstruction in the BESⅢ muon counter

The reconstruction algorithm for BESⅢ Muon Counter, MucRecAlg, is developed with the object-oriented language C++ in BESⅢ offline software environment. MucRecAlg consists of the following functions: to find track seeds either from extrapolation of tracks in the main drift chamber or from the fired strips in muon counter, to select fired strips associated to the candidate tracks, to fit the candidate tracks with a linear or quadratic function and to calculate other parameters of the tracks for muon identification. Monte Carlo samples are generated to check the performance of the reconstruction package, such as reconstruction efficiency, muon remaining rate and pion rejection rate, etc. The preliminary results show that the pion rejection rate is around 3%-4% while the muon remaining rate is better than 90% in 0.4-1.6 GeV/c momentum region, which meets the requirement as shown in the design report.     

Chemical Potential Dependence of the Dressed—Quark Propagator from an Effective Quark—Quark Interaction

We exhibit a method for obtaining the low chemical potential dependence of the dressed quark propagator from the dressed-quark propagator,which provides a means of determining the behavior of the chiral and deconfinement order parameters.A comparison with the results of previous researches is given.     

Effect of a Small Current Quark Mass on Bag Constant

A method for obtaining the small current quark mass effect on the dressed quark propagator within the Dyson Schwinger approach is developed. From this the small current quark mass dependence of the bag constant is evaluated. It is found that the bag constant decreases with the increasing current quark mass and the contribution of the current quark mass cannot be dropped.