1996 Vol. 20, No. 8

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The Decay Scheme of 175Er
Zhang Xueqian, Yuan Shuanggui, Yang Weifan, Mou Wantong, Yu Xian, Li Zongwei, Guo Tianrui, Du Yifei, Luo Yixiao
1996, 20(8): 673-677.
The 175Er activity was produced via the reaction 176Yb(n,2p) 175Er by 14MeV neutron irradiation of a natural ytterbium metal target with a thickness of~80mg/cm2.X-γ and γ-γ coincidence measurements were employed to identify 175Er activity.The half-life of 175Er has been determined to be (1.2±0.3)min. Eight new gamma rays were assigned to the decay of 175Er. A partial decay scheme of 175Er has been proposed for the first time, from which a ground rotational band has been assigned to 175Tm.
Study of the Micro Strip Gas Chamber
Yu Zhongqiang, Wang Shunshin, Wei Hornjer, Chu Minglee, Teng Pingkun
1996, 20(8): 678-684.
We report on the manufacture and the experimental investigations of small gap MSGCs (anode-cathode gap of 4-14μm). The reached maximum gains for small gap .MSGCs are about 1000. There are better stabilities for the small gap MSGCs with the anode width of 3μm at the low rate (~10Hz /mm2), and the variations of the gains are within ±1% during a twenty -hours period.
The Correlation Between the Transverse Polarization andTransverse Momentum of Lambda Produced in RelativisticNucleus-Nucleus Collisions
Ye Yunxiu, Su Shufang, Zhou Xin, Zhu Guohuai, Ji Gang
1996, 20(8): 685-690.
The transverse polarization of lambda produced in relativistic nucleus-nucleus collisions is determined. The effect from the interaction between spin moment and magnetic field is corrected. The near zero transverse polarization and non-correlation between transverse polarization and transverse momentum are obtained and compared to ones obtained from the nucleus-nucleus interactions at lower energies. This comparison shows that the production mechanism of lambda in the relativistic nucleus-nucleus collisions is different from one in the nucleus-nucleus reactions at lower energies.
QCD Sum Rules for the 0++ Three-Gluon Scalar Glueball
Lu Wentao, liu Jueping
1996, 20(8): 691-697.
The two-point function of the 0++ three-gluon scalar current is calculated by including not only the perturbative contribution but also the non-perturbative contributions of condensates of dimension up to six The QCD sum rules for the 0++ three-gluon scalar glueball are deduced in the "zero-width resonance plus continuum" model. The mass of this glueball is determined to be 1.45GeV approximately.
Feynman Rules and Generalized Ward Identities in Phase Space Functional Integral
Li Ziping
1996, 20(8): 698-702.
Based on the phase-space generating functional of Green function, the generalizedcanonical Ward identities are derived It is point out that one can deduce Feynmanrules in tree approximation without carring out explicit integration over canonicalmomenta in phase-space generating functional. If one adds a four-dimensionaldivergence term to a Lagrangian of the field, then, the propagator of the field can bechanged.
Eigenstates of the Higher Power of the Annihilation Operator ofTwo-Parameter Deformed Harmonic Oscillator
Wang Jisuo, Sun Changyong, He Jinyu
1996, 20(8): 703-706.
Abstract:The eigenstates of the higher power of the annihilation operator aqsk(k≥3) of the two-parameter deformed harmonic oscillator are constructed. Their completeness is demonstrated in terms of the qs-integration.
Analysis of the Coherence of Pion Emitting SourceThrough Multipion Correlations
Zhang Weining, liu Yiming, Huo Lei
1996, 20(8): 707-714.
The multiparticle correlations of pious eastted from sources with different degrees of coherence are simulated by Monte Carlo method. The sensitivity of the dependence of the multipion correlations in subevents with different multiplicities on the degree of coherence of the pion-emitting source is investigated. The degrees of coherence of the sources for central collisions of 2.1A GeV Ne+Pb and 1.2A GeV Ar+KCl at the Bevalac streamer chamber are analyzed. The results are compared with previous two-pion interferometry results.
The Continuous Scale Behaviour of Random Cascading Model
Zhang Yang, Wu Yuanfang, Liu lianshou
1996, 20(8): 715-722.
The traditional method of calculating factorial moments with discretely diminishing scale is generalized to the case of continuously varying scale. It is shown that the random cascading model currently used has a "Chain effect" With continuously diminishing scale. Taking the actual processes of experiment into account, a revised model is proposed which can give good scaling property also for continuously varying scale when the volume and location of phase space region in consideration are fluctuating randomly. The fluctuation parameter of phase space region meeting this condition is insensitive to the model parameter α. This kind of fluctuation of phase space is proved via Monte Carlo simulation to have no big influence upon the anomalous scale index.
Study of the Structure Effect in Fragment Formation Process in HIC
Liu Hang, Liu Jianye, Li Junqing
1996, 20(8): 723-728.
Based on usual QMD, by considering restructured aggregation model, neutron and proton disdinghshing, description of the fermionic behavior of nucleons and frictional cooling method, a new kind of MQMD is proposed. The distribution and time stability of some isotopes in reaction 12C+12C at Elab=28.7MeV/u are studied by this model. The results show that this new MQMD can well describe the structure effect in the fragment formation in HIC.
Competition Among the Decay Modes of Projectile Remnantand Its Evidence in ALADIN Data
Wang Fei, Sa Benhao, Zheng Yuming, Zhang Xiaoze
1996, 20(8): 729-735.
The relative yield of the decay modes of the projectile remnant as a function of <Zbound> is analysed for the first time from ALADIN data of An (600MeV/u)CU+Au,and they are consistent with the corresponding theoretical results of Incomplete-Fusion-Fragmentation Model. Both the experimental and the theoretical results of the relative yield of decay modes, of the Dalitz plot, of the Campi plot and the theoretical results of thermodynamical temperature plot, all nicely show the competition and the transformation of the decay modes of projectile remnant with the decrease of <Zbound>.
Study on the Structure of Hypernuclei ΛΛ5H,ΛΛ5He,ΛΛ4He and ΛΛ4H
Cheng Zitao, Liu Xianhui
1996, 20(8): 736-744.
In this paper, double Λ binding energies BΛΛ s of ΛΛ5He(ΛΛ5H), AA4He and ΛΛ4H are calculated with the help of few-body models. The results show that stable binding state for ΛΛ5H or ΛΛ5He exists definitely with BΛΛ(ΛΛ5H)=6.75MeV and BΛΛ(ΛΛ5He)=7.67MeV,respectively. As to ΛΛ4He and ΛΛ4H, preliminary results indicate that ΛΛ4H is unstable against decaying into Λ+Λ3H, and ΛΛ4He has no binding state.
Gamow-Teller Transitions of Nuclei With A=147-153
Zhang Changhua, Gu Jinnan
1996, 20(8): 745-749.
In this paper the Gamow-Teller transitions are systematically investigated for nuclei with A=147-1.53 in terms of the shell-model. These nuclei have only GT decay channel π1h11/2→v1h9/2. The overall comparisons of the experimental reduced probabilities Bexp(GT) with the calculated Bcal(GT) show that there is a quenching factor γ2 with optimum value 0.17±0.05 in this mass region.
Effect of Rotation on Transition Energies and M1 Transitions in Superdeformed Nuclei
Xing Zheng, Chen Xingqu, Wang Xiaochun
1996, 20(8): 750-755.
Using triaxial-particle-rotor model, a strong perturbation effect of rotation on transition energies and M1 transitions is investigated. The γ-transition energies,B(M1) -values and n γ-ray intensity are given. The M1 tranSitions between signature partner bands in the 195T1 nucleus may proceed mainly through internal conversion electrons.
Upgrading at the BEPC Control System
Zhao Jijiu, Geng Xiaosong, Yu Yulan, Wang Bingfeng, Wang Chunhong, Xu Jingwei, Liu Wei, Luo Huiying, Wang Yaru, Lu Jihua, Yan Yonghe, Zhan Mingchuan, Wang Youheng
1996, 20(8): 756-762.
The Beijing Electron Positron Collider (BEPC) serves physical experiments andsynchrotron radiation applications. The BEPC control system was a centralized controlsystem built by the end of 1987. The upgraded control system adopts distributionarchitecture with Ethernet. The workstations are used as console to replace theold hardware console, the new VAX computers carry oat control jobs and somededicated adapters have been eliminated. The main effort in upgrading the controlsystem is the software side and the system upgrading is crowned with success.
Study of Surface Blistering and Pinhole Formationon Argon Ion Bombarded Amorphous Alloys
Liu Changlong, Hou Mingdong, Quan Mingxiu, Sun Wensheng
1996, 20(8): 763-768.
Amorphous alloy (Co94Fe4Cr2)78Si8B14 was bombarded with argon ions at energies of 150keV and 195keV respectively. Above a critical fluence blistering and sputtering erosion were the two main surface damage phenomena. The critical fluence for onset of pinhole formation was determined and found to increase with ion energy. The density of pinhole increases with ion fluence dramatically and at a certain fluence, it reaches saturation. However, with the formation of pinhole, the density of blister decreases rapidly and a kind of porous structure is developed at a certain fluence.These results were interpreted with sputtering and rupture of bubbles.