1998 Vol. 22, No. 7

Display Method:          |     

The δ Ray Effect in Particle ldentification via Cherenkov Correlated Timing
Zhu Yongsheng, Chen Jiangchuan, Cheng Baosen
1998, 22(7): 577-586.
The interference effect from δ electrons created by primary particle passing through radiator in Cherenkov Correlated Timing (CCT) technique is discussed, and the possible method to diminish this interference effect is proposed. The capability for π/K separation is given by Monte Carlo simulation for CCT design of the Beijing Tau-Charm Factory.
A New Method of Track Finding and Fitting in Main Drift Chamber of BES-Ⅱ
Liu Jing, Mao Zepu, Li Weiguo, Zhang Changchun, Chen Guangpei, Yan Wugung, Li Peiqin, Rong Gang, Zhao Haiwen, Xie Yu
1998, 22(7): 587-595.
This paper introduces a new algorithm that is used to find and fit charged particle tracks in MDC of BES-Ⅱ. The non-numerical pattem recognition technique used in this algorithm is described. The technique is both fast and efficient from the analysed results of M. C. data and experimental data.
Temperature Parameters Extracted in 40Ar Induced Reactions at 30MeV/u
Xu Hushan, Zhu Yongtai, Gou Quanbu, Wei Zhiyong, Lu Jun, Wang Qi, Li Songlin, Zhang Yuhu, Jin Genming, Wu Zhongli, Xie Yuanxiang
1998, 22(7): 596-601.
By employing the method of double ratios of isotope yields, the nuclear temperature parameters for the reactions of 30MeV/u 40Ar bombarding 58Ni,64Ni and 115In targets. are extracted by yields of the fragments of 3≤Z≤8. The dependences of the apparent temperature on some observables are investigated. The temperature values after correction for the side-feeding effects are also deduced and discussed.
Inhomogeneous Inverse Differential Realizations of the SU(2) Group
Yu Zhaoxian, Zhang Dexing, Liu Yehou
1998, 22(7): 602-606.
The generators and irreducible representation coherent state of the SU(2) group are constructed using the inverse operators of bose harmonic oscillator. The inhomogeneous inverse differential realizations of the SU(2) group are derived.
Study of ξ(2230) Produced in J/ψ Radiative Decay Process
Chao Ming, Shen Qixing, Yu Hong
1998, 22(7): 607-613.
The processes e+e→J/ψ→γ+X, X→pp are discussed usiag the generalized moment analysis method. The moment expressions of the above processes are given, And they are used to detennine the spin of the resonance X decaying to pp. The helicity arnplitude ratios of the ahove processes in terms of moment expressions are also given.
Two-Loop Thermodyn amic Potential of Pure Gauge Fields in QGP
Wang Xin, Li Jiarong
1998, 22(7): 614-625.
In hard termal loops (HTL) rcsuramadon scheme, we calculate the thermo- dynanmtc potendal of pure guage fields to two-loop level in quark gluon plasma (QGP) and perfonm its renomalizadon employing dimensional regularizadon (DR). The result with collecdve effects is obtained.
Dilepton Production in Expanding Hot Baryon-Rich Quark-Gluon Matter
He Zejun, Zhang Jiaju, Wang Zixing, Qiu Xijun
1998, 22(7): 626-630.
From the full stopping scenuio, the dilepton producdon in the baryon-rich quarktgluon fircball is studicd based on a reladvisdc hydrodynamic model. It is found that with increasing incident cnergy a characteristic plateau indicadng the formation of the baryon-rich quarktgluon matter appears in the total yield. This obvious characteristic can be tested in future experiments at CERN and Brookhaven.
Revisit to Minijets in pp Collisions at s=630GeV
Liu Feng(Y), Liu Feng
1998, 22(7): 631-638.
According to jet definition-cone algorithm to identify jets, we reanalyse UA1 minimum-bias non-single diffractive pp data at s=630GeV, The correlations between pt and multiplicity for the event sample and subsamples are studied in detail. We found that they are positively correlated for the event sample, while negatively correlated for the jet event subsample. The correlations and decorrelations between mini-jets are also studied. We further analyse the possibility of large rapidity gap existence between the two minijets, and find that there are no particles between two minijets in some events, but the statistics are not enough.
Effect of Fission Path on Prescission Particle Emission
Ye Wei, Shen Wenqing, Feng Jun, Ma Yugang, Wang Jiansong, Cai Xiangzhou, Wu Xizhen, Feng Renfa, Lu Zhongdao
1998, 22(7): 639-645.
The elapsed time of system from saddle to scission and the ratio of particle emission from saddle to scission to presaddle emission as a function of mass of fissioning system were studied based on the diffusion model. A possible interpretation for the dependence of prescission particle emission on fission fragment mass asymmetry is given. The analysis shows that the above two relations can be ascribed to the fissioning path effect.
Extending of the Bragg Peak of Heavy lon Beam
Li Qiang, Wei Zengquan, Li Wenjian, Zhou Guangming, Dang Bingrong, Cai Xichen, He Jing, Xie Hongmei, Han Guangwu, Huang Tao, Chen Weiqiang, Wang Jufang, Zhang Shumin
1998, 22(7): 646-650.
A rotating range modulator designed and manufactured in IMP is introduced, which is applied to extend Bragg peak of heavy ion beam. With double ionization chamber method, Bragg curve of 75MeV/u 12C ions and Modulated Bragg curves of 75MeV/u 16O and 75MeV/u 12C ions through this range modulator were measured respectively, and two evident spread-out Bragg peaks corresponding to the modulated beams above are shown. The calculated curves are also exhibited for comparison.
EPR Studies on Defect Production and lts Annealing Behavior in Silicon After High Fluence Ar lon lrradiation
Liu Changlong, Hou Mingdong, Cheng Song, Zhu Zhiyong, Wang Zhiguang, Sun Youmei, Jin Yunfan, Li Changlin
1998, 22(7): 651-657.
Silicon samples were irradiated below 50K with 1 12MeV Ar ions to a fluence of 8×1014/cm2. Defect production and its isochronal annealing behavior have been investigated at room temperature by Electron Paramagnetic Resonance technique. Neutral 4-vacancy (Si-P3 center), positively charged 〈100〉 splitted di-interstitial (Si-P6 center) and the contiuous amorphous layer have been detected in the as-irradiated sample. At an annealing temperature of 200℃ , the Si-P3 and Si-P6 centers were annealed out and five vacancy cluster in negative charge state (Si-P1 center) began to grow. The Si-P1 center disappeared at about 550℃. For the temperature above 350℃, Si-A11 center (a center may include several vacancies) has been observed, which was stable up to 550℃, The temperatue for recrystallization of the continuous amorphous layer is higher than 600℃. During the annealing process, the line shape and line width for amorphous center were not changed. The results are qualitatively discussed.
Recent Experimental Status of Glueball Search
Zhu Yucan
1998, 22(7): 658-671.
This paper described the recent experimental status of glueball search, and it particularly centred on the situation of confinmation about. Scalar and Tensor glueballs.