1997 Vol. 21, No. 05

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Review
Measurements of the Branching Ratios for the Decays J/ψ→γπ0,γη, γη'→ 3γ at BES
BES Collaboration
1997, 21(05): 385-392.
Abstract:
Decays of the J/ψ resonance into the final states with three photons are investigated.Branching ratios for the decays of J/ψ→γπ0 and J/ψ→γη'are determined to be Br (J/ψ→γπ0)=(4.6±1.1)×10-5 and. Br(J/ψ→γη')=(4.12±0.82)×10-3. The ratio of the two decay rates,(J/ψ→γη')/(J/ψ→γη),is 4.79±0.85. Within experimental errors, this value agrees well with the predictions of two theoretical models'.
High-Spin States in 162Lu and Signature lnversion of Yrast Bands in Doubly Odd Nuclei Around A=160 Mass Region
Zhang Yuhu, Zhao Qingzhong, Zhou Xiaohong, Sun Xiangfu, Lei Xiangguo, Guo Yingxiang, Liu Zhong, Chen Xinfeng, Zhu Yongtai, Wen Shuxian, Yuan Guanjun, Liu Xiangan
1997, 21(05): 393-401.
Abstract:
High-spin states in 162Lu have been roduced and studied via 147Sm (19F, 4nγ) 162Lu reaction. lh-beam γ-rays were measured by using 1 planar detector and 7 high purity Ge detectors with BGO anti-Compton Shield. The level scheme of the yrast band in 162Lu was established for the first time and the signature inversion in energy was discovered for The yrast bands of doubly odd nuclei around A=160 mass region have been reinvestegated and the systematics of signature inversinon was discussed briefly.
Isotope Distribution of Ir Produced in Intermediate Energy 12C on 197Au
Zhao Zhizheng, Hu Zhiqinang, Yang Weifan, Li Zongwei, Sun Xiurong, Qin Zhi, Yang Yongfeng, Mu Wantong, Xie Xiujun, Zhang Li, Yuan Shuanggui, Wu Dingqing, Cai Xichen
1997, 21(05): 402-407.
Abstract:
Yields of lr isotopes from 12C (47MeV/u)+197Au have been measured by using chemical separation and γ spectroscopy method. The lr isotope distribution was ob tained after correction for decay during the irradiation period by using the accutnulation yields of Pt. The cross sections of A>170 neutron-rich isotopes , the Qgg systematics of cross sections and the residual excitation energy of target - like frafpnents are discussed.
Moment Analysis of J/ψ Decay Processes and Comparison of Results in Two Frames
Shen Qixing, Chao Ming, Yu Hong
1997, 21(05): 408-412.
Abstract:
The density matrices of J/ψ produced in the non-polarized e+-e collisions in both experimental laboratory and helicity frame are discussed. The results show that rthe conclkusion for only J/ψ with the helicity ±1 having contributions to the procss is correct only in the experimental laboratory frame under some conditions. The number of the moments is the same and there is a simple relation between the moments in the two frames.
A Study on Rare Radiative Decay Bc→Dsγ in Technicolor Models
Lu Gongru, Xiong Zhaohua, Cao Yigang, Yang Yadong
1997, 21(05): 413-424.
Abstract:
We calulate the psedo-Goldstone-bosons (PGB) contributions to the decay Bc→Ds γ in one generation technicolor model (TCI) and the technicolor model with massless doublet (TCⅡ),and compare with the contributions estimated in the standard model. We find that the contributions of PGBs in the TCI to the electri-magnetic penguin dirgram are large, whereas those of the TCⅡ are small. However, the contributions to the weak annihilation diagrams can be neglected. It is expected that the difference of the branching ratio Br (Bc→Dsγ)in various models can be studied at LHC in near future, and will be an important test to different models.
Regularization of Infrared Divergences in the Vacuum Graphs of Massless Field at Finite Temperature
Chen Xiangjun, Liu Lianshou
1997, 21(05): 425-432.
Abstract:
The infrared divergences of three-loop vacuum graphs of massless scalar and gluonfields and their regularization are discussed. The expression for analytical continuation is given. How to seperate the infrared and collinear divergences from overlap ones is also discussed.
Nuclear Gluon Distributiom in the Extended x-Rescaling Model
Duan Chungui, He Zhenmin, Lin Zhongjin, Li Guanglie
1997, 21(05): 433-437.
Abstract:
Using the extended x-rescaling model and taking account of the nuclear shadowingeffect by the spatial overlap of sea quarks and gluons from neighbouring nucleons in the nucleus in small x region, we calculate the ratios Gsn(x)/Gc(x). The calculated results arein good agreement with recent NMC experimental data.
Nuclear Pair Shell Model and Its Numerical Calculation (Ⅱ)
Zhao Yumin, Chen Jinquan
1997, 21(05): 438-444.
Abstract:
Within the framework of the nuclear pair shell model, numerical calculation is performed in the truncated SD subspace. In this calculation, the S pair is taken as that from the BCS calculation, the D pair is obtained through D=for the even-even nuclei with cases in the region. The contributions from the single particle energy term H and from the abnormal parity level are discussed.
A Static Theory for Nuclear Multifragmentation Ⅱ.lntermittent Pattern and Critical Behaviour
Zhang Fengshou, Ge Lingxiao
1997, 21(05): 445-452.
Abstract:
A Simulation is carried out for five different phases of nuclear equation of state. thegas, the liquid, the super heated liquid, the super cooled gas and the mechanical instability of spinodal phases, which are obtained from a deasity, tempemperature, and momentum depen dent mean field for 197Au at finite temperature T=6MeV in real space and in momenturn space The nuclear cluster is sorted a coalescence model. lt is demonstrated that the intermittent pattern comes from the mechanical ionstability of spaiodal phase and the criti cal behaviour comes mainly from the mechanical instability of spinodal phase while there is also a small contribution from the super heated liquid phases from the analyses of the conditional moments and the scaled factorial moments.
Isomeric Cross Section Ration for (n,2n)Reaction
Huang Xiaolong, Cai Dunjiu
1997, 21(05): 453-457.
Abstract:
Monte Carlo Calculations of the isomeric cross section ratio for (n,2n)reaction based on the compound nuclear reaction theories and exciton-model are presented. Thecalculations are compared with experimental measurements for 59Co (n,2n)58Co, 93Nb(n,2n)92Nb and 181Ta(n,2n) 180Ta reactions in the energy region from threshold to 20MeV. The agreemeat between calculation and experiment indicates that the present method is suitable to calculate the isomeric cross section ratio for (n,2n)reactions.
Dependence of Pion Source Radius and BE Coherent Radius on Experimental Wiadows and Their DIffrence
Lu Zhongdao, Osamu Miyamura, Kenji Kumagai, Shin Muroya
1997, 21(05): 458-464.
Abstract:
The relationship between Bose-Einstein coheremt radius and source radius (orroot-mean-square radius),and their dependence on the experimental windows of rapidity and transverse momentum are studied for pion source in 160A GeV/c Pb+Pb collisions,The model pion source is Produced by generator URASiMA. The results show that the coherent radius and source radius at freeze-out not only have difference in magnitude but also in behavior.
Q-Effect of Structures of 3-Particle Systems
Xie Wenfang
1997, 21(05): 465-469.
Abstract:
The different modes are to Study the effect of the compet ition between the energy internalvibration and thecollective rotational energy. It is found that thie competition will affect the geometricstu cture and the space orientation. of the states of 3-Particle systems.
Experimeotal Study of a Multi - Cavity BF Gun With Thermionic Cathode
Tang Chuanxiang, Wu Yuanming, Wang Youzhi, Zhao Xinqiao, Lin Yuzheng, Xie Jialin
1997, 21(05): 470-474.
Abstract:
A novel multi-cavity RF thermionic gun with much less back bombardment effect has beea designed, built, tested and experiraeated. ln this paper we mainly discuss the expermental results of this RF gun From the pulse shapea of BCT at the gun exit and energy spectra at different. positions of the pulse, we have seen that the back bombardment power is much less than the single cavity RF gun. The current after the a-magnet is 200mA, and electron energy is about 1.8MeV. The geometric RMS emitttance is less than 28π nm . mradia x-direction, and lessthan 22π·mm·mrad in y-direction at the linac entrance.
Microprobe X-Ray Fluoresceoce Experintental Station of Beijing Syochrotron Radiation Facility
Wu Yingrong, Chao Zhiyu, Pan Juxiang, Hong Rong, Xiao Yanan, Li Guangcheng, Huang Yuying, Zhao Limin
1997, 21(05): 475-480.
Abstract:
The synchrotron radiation (SR)microprobe XRF experimental station of Beijing Synchrotron Radiation Facility (BSRF)is located at the end of the 4W1A white SR beam line.The major instruments of the station are: ion chamber system for beam intensity monitor; slits and laser collimation system;multidimensional sample stage andits stepping motor driviing system; tele-microscope and video viewing system; Si(Li)energy dispersive spectrometer.The equipment has very high sensitivity (absoluteMDL, 10-10—10-13g,relative MDL:N×μg/g-N×0.1μg/g,and relative MDL fortotal reflection XRF is 1-5ng/g),good spatial resolution (50μm for thick sample,200μm for Bio-tissue). A lot of researches were performed on Geo-Science,Bio-Science,Material Science and so on.