1996 Vol. 20, No. S1

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Synthesis and Gamma Decay of New Heavy Neutron-Rich Isotope 175Er
Yang Weifan, Yuan Shuanggui, Zhang Xueqian, Yu Xian, Mou Wantong, Li Zhongwei, Gan Zaiguo, Liu Hongye, Guo Junsheng, Zhong Jiquan, Sun Xiangfu
1996, 20(S1): 1-2.
A new isotope 175Er was synthesized for the first time by the 176Yb(n,2p)175Er reaction in irradiation of natural metal ytterbium targets with 14 MeV neutrons. The activities of 175Er were observed by γ(X) ray spectroscopy. Eight new γ rays of 76.5, 120.9, 123.7, 128.5,227.3,234.0,281.4, and 1167.5 keV with half-life of 1.2±0.3 min were found and assigned to the β decay of 175Er. A partial decay scheme of 175Er was proposed.
Emission-Time Measurements of Light Particles from 40Ar+197Au Collisions in Intermediate Energies
He Zhiyong, Duan Limin, Li Zuyu, Jin Genming, Luo Qingzheng, Wu Heyu, Zhang Baoguo, Wen Wanxin, Qi Yujin, Dang Bingrong, Dai Guangxi
1996, 20(S1): 3-7.
Particle-particle correlation functions have been measured for 40Ar+197Au collisions at E/A=25 MeV. Emission time of light particles has been extracted from correlation functions using the three-body trajectory model. The average emission time varies with the energy of particles. It decreases from about 300 fm/c for low energy particles to about 100 fm/c for energetic particles.
Hafnium Production from the Reaction of 6.3-24.6 MeV/nucleon 40Ar+natW
Zhang Xiang, Li Wenxin, Sun Tongyu, Yin Xinmin, Qin Zhi, Zhao Lili, Wu Dingqing, Zheng Jiwen, Liu Gouxing
1996, 20(S1): 9-13.
The yields of known hafnium isotopes produced in 6.3-24.6 MeV/nucleon 40Ar+natW reactions were determined by γ-ray spectroscopy following chemical separation. The excitation function, the FW value, and isotope distributions were obtained. It was deduced that using HIRFL energy heavy ions to synthesize new neutron-rich nuclides in the A > 170 region is possible. Using thick target or multi-thin target can obviously increase the yield of a new neutron-rich nuclide. Increasing projectile energy is not always helpful to synthesize a new neutron-rich nuclide.
First Experimental Determination of Half-Life for New Nuclide 65Se
Huang Wenxue, Xu Xiaoji, Hu Zhiqiang, Ma Ruichang
1996, 20(S1): 15-21.
By using experimental data obtained from the measurement of β-delayed proton decay of 65Se produced in the 40Ga(28Si,3n) reaction, the absolute detection efficiency of particle telescope for rotating radioactive source was fitted and calculated. The half-life of 65Se was thus accurately determined to be 9.6-4.1+5.3 ms and its β-delayed proton energy of 65Se was 3.70±0.08MeV. The partial decay scheme of 65Se β-delayed proton decay was revised.
A Two-Dimensional Position Sensitive Multi-Stage Detection System with a Wide Dynamic Range for Heavy Ion Reaction
Wang Jinchuan, Zhan Wenlong, Guo Zhongyan, Xi Hongfei, Zhou Jianqun, Zhao Youxiong, Lei Huaihong, Luo Yongfeng
1996, 20(S1): 23-29.
A two-dimensional position sensitive multi-stage detection system with a wide dynamic range for a heavy ion reaction is described in this paper. It consists of four parts:a longitudinal electric field gas filled Ionization Chamber (IC), a Position Sensitive Silicon Detector (PSSD) (45 mm×45 mm, 400 μm), a large area PIN Silicon Photodiode (SPD) (48 mm×48 mm, 300 μm),and a 16 element CsI(Tl) scintillation detector array. The energy resolutions for IC and PSSD tested with a source 241Am(5.486 MeV) are 3% and 2.6%, respectively. The energy dynamic range for α particle detection is about 2-130 MeV, and the fragments with Z Values from Z=2 to Z=21 are identified in the reaction of 25 MeV/u 40Ar+ 115In. The Z resolving power is Z/△Z ≈ 44.5 (FWHM) for Z=18. The position resolution of PSSD is 0.86±0.03 mm (FWHM).
Synthesis and Identification of the New Neutron-Deficient Isotope 235Am in the Transuranium Region
Guo Junsheng, Gan Zaiguo, Liu Hongye, Shi Lijun, Yang Wefan, Mou Wantong, Guo Tianrui, Fang Kerning, Shen Shuifa, Yuan Shuanggui, Zhong Jiquan, Zhang Xueqian, Qin Zhi, Ma Ruichang, Wang Shuhong, Kong Dengming, Qiao Jimin
1996, 20(S1): 31-32.
A new neutron-deficient isotope235Am was synthesized in the reaction of 238Pu(p,4n)235Am by using 35 MeV proton bombarding 238Pu target. The products were transported by the He-jet system. The Am was separated from the reaction products using the radiochemistry method. The γ-ray of 235Pu and X-ray of Np following the EC decay of 235Am were observed. Based on the growth-decay curve of X-ray of Np and the X-γ coincidence measurements, the synthesis of 235Am was confirmed for the first time. The measured half-life of 235Am is 15 ±5 min.
2-D Cyclic Representations of Uq(sl(2)), C-G Coefficients,and a Free Fermion 8_Vertex Model
Zhang Jun, Yang Guangcan, Yan Hong
1996, 20(S1): 33-38.
We construct explicitly the two-dimensional cyclic representation of quantum algebra Uq(sl(2)) with q=i and z central extension. The representation is irreducible and we write down explicitly the Clebsch-Gordan coefficients and the intertwiner of tensor representations in different orders. This intertwiner turns out to be an 8-vertex R-matrix that satisfies the free-Fermion condition and therefore gives an integrable model.
A Two-Parameter Deformed Two-Dimensional Interacting Boson Model with Uqp(U3)⊃Uqp(U2)⊃Uqp(SO2) Symmetry
Zhou Huanqiang, Guan Xiwen, He Jingsong
1996, 20(S1): 39-46.
A two-parameter qp-deformed two-dimensional interacting boson model (IBM) with the quantum symmetry Uqp(U3)⊃Uqp(U2)⊃Uqp(SO2) is constructed. It is found that the energy spectra and the transition matrix elements depend very sensitively on the second parameter of deformation.
Phase Structure of U(l) Lattice Gauge Theory by Variational Study with Independent Plaquette Effective Action
Zhao Peiying, Wu Jimin
1996, 20(S1): 47-54.
The plaquette internal energy Ep of U(1) lattice gauge theory (LGT) in three dimensions is calculated using the variational cumulant expansion (VCE) with the independent plaquette effective action. The Ep-β curve is continuous, which shows that the U(l) theory is confined. Our result is consistent with Monte Carlo (MC) data.
Massive Fermion Loop Contribution to Casimir Force in Two-Dimensional Case
Zheng Taiyu, Li Changsong
1996, 20(S1): 55-59.
Using the Feynman path integral method, we calculate the Casimir effect of QCD with massive fermion loop contribution between two parallel ideal conducting wires at zero temperature.
Invariant-Related Unitary Transformation and the Evolution of the Wave Function of the Universe in Third-Quantized Cosmology
Gao Xiaochun, Gao Jun, Fu Jian
1996, 20(S1): 61-69.
On the basis of the generalized invariant theory, the invariant-related unitary transformation method is developed and used to study the evolution of the third-quantized wave functions of the universe. The expressions for the phases and the wave functions are obtained. Then, by means of the construction of the coherent state, the solutions of the Wheeler-DeW itt equation and the quantum fluctuations caused by the third quantization are found.
Analytical Study of Two-Dimensional Self-Affine Fractal in Multiparticle Production of High Energy Collisions
Lin Hai, Zhang Yang, Liu Lianshou
1996, 20(S1): 71-83.
The self-affine cascading model of 2-dimensional phase space is discussed in some detail. The analytical expression for the scaled probability inoments, CN2 and CN3 are deduced for the self-similar analysis of a 2-dimensional self-affine fractal object with Hurst exponent H=0.5. The Levy stability indices of the model are calculated analytically. It is shown that the results of Levy indices from the Monte Carlo simulation are consistent with those from the analytical calculation. The recent experimental data from NA22 collaboration are explained qualitatively.
20Ne+12C System and the Double-Alpha Transfer Effect for a Deep Optical Potential
Gao Chengqun, Yang Baosheng, Zhou Quanhua
1996, 20(S1): 85-91.
In this paper, the basic features exhibited by the 20Ne+12C system are analyzed and the excitation functions and the angular distributions of the 20Ne+12C elastic scattering are well reproduced on the basis of the nuclear molecular orbital theory. The results show that the double-alpha transfer effect for a deep optical potential is responsible for the basic features in the excitation functions of the 20Ne+12C elastic scattering.
Studies of the Low-Lying States in 157, 159Tm
Xing Zheng, Chen Xingqu, Xu Shuwei
1996, 20(S1): 93-100.
Properties of the low-lying positive-parity states in 157, 159Tm have been investigated by using the triaxial rotor plus particle model with the variable moment of inertia (VMI) of the core. The good agreement between theory and experiment shows that 157Tm and 159Tm may be triaxiality. Furthermore, it is suggested that an excitation rotational band in 157Tm probably already exists in the experimental data.
Ground-State Properties of the Doubly-Magic Nucleus 100Sn
Wen Wanxin, Jin Genming, Zhong Jiquan
1996, 20(S1): 101-106.
The ground state properties of the doubly-magic nucleus 100Sn were calculated with the Skyrme-Hatree-Fock method. There may be a proton skin in the 100Sn nucleus due to the Coulomb repulsion.
Validity of the M-3Y Force Equivalent G-Matrix Elements for Heavy Nuclei
Cheng Lan, Huang Weizhi, Zhou Baosen
1996, 20(S1): 107-112.
The matrix elements of the M-3Y force are adopted as equivalent G-matrix elements and the folded diagram method is used to calculate the spectra of 210Pb, 206Pb, 206Hg, and 210Po. Results show that the matrix elements of the M-3Y force as equivalent G-matrix elements are suitable for the microscopic calculations of the nuclear structure in the heavy nucleus region.