1994 Vol. 18, No. S1

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Observation of a Possible πh11/2 band of 117Cs
Sun Xiangfu, Liu Zong, Zhou Xiaohong, Lei Xiangguo, Jin Hanjuan, Pan Qiangyan, Zhang Yuhu, Guo Yingxiang, Cheng Xinfeng, Luo Yixiao, Wen Shuxian, Yuan Guanjun, Li Guangsheng, Yang Chunxiang
1994, 18(S1): 1-4.
A new rotational band has been identified in the reaction of 28Si+92Mo by means of in beam γ-ray methods.It is considered as the possible h11/2 proton band of 117Cs,through a careful analysis of its intensity and level characters.
A Test of Sequential Decay of Hot Nuclei Around 3MeV/u Excitation Energy
Wu Heyu, Dai Guangxi
1994, 18(S1): 5-12.
The decay properties of excited nuclei corresponding to about 3MeV/u excitation energy formed in incomplete fusion reactions 40Ar(25MeV/u)+209Bi、197Au、159Tb are analysed.The sequential decay of nuclei by large fragments is identified using a minimization procedure of relative velocity difference with coulomb repulsion velocity.It is shown that three fragments originate from two successive independent binary splittings.This result is also supportted by the fact,that the experimental angular distribution of ternary fragments is nicely reproduced by sequential decay.
A Multitelescope System for the Measurement of Differential (n,Charged Particle)Reaction Cross-sections
Ye Banjiao, Fan Yangmei, Wang Zhongmin, Han Rongdian, Mei Wen, Yu Xiaoqi, Yang Yanming, Han Renyu, Du Huaijiang, Xiao Zhenxi
1994, 18(S1): 13-19.
A multitelescope system for measurement of double-differential cross-sections for the (neutron,charged particle)reactions is designed.The system consists of two ΔE multiwire proportional chambers and a central CsI(Tl) energy detector.Fastslow triple-coincidence was used to select all signals.An electronics system for acquiring five-parameters for the products from the (neutron,charged particle)reaction was established.The system allows simultaneous measurements of the energy spectra of charged particles at 16 reaction angles from 30°—160°and the background spectra.
Ternary Fission Fragments Correlation Measurement in Reactions of 40Ar+159Tb,197Au,209Bi at 25MeV/u
Dai Guangxi, Wu Heyu, Jin Genming, Qi Yujin, Li Zuyu, Duan Limin, He Zhiyong, Luo Qingzeng, Wen Wanxin, Zhang Baoguo, Dang Bingrong, Cai Wei
1994, 18(S1): 20-27.
Three fragments emitted from the decay of hot nuclei formed in central collision of 25MeV/u 40Ar with 159Tb、197Au、209Bi were measured coincidently.In these cases,the corresponding excitation energy of hot nuclei is about 3MeV/u.The distributions of the mass,the relative angle and relative velocities are obtained by correlation measurement.The probability ratio of ternary fission relative to binary fission in detector space has been modified to 4π geometry in terms of Monte-Carlo method.
Study of Low-lying Level Structure in 198Pb
Zhou Xiaohong, Sun Xiangfu, Lei Xiangguo, Jin Hanjuan, Liu Zhong, Zhang Yuhu, Pan Qiangyan, Guo Yingxiang, Chen Xinfeng, Luo Yixiao, Wen Shuxian, Yuan Guanjun, Li Guangsheng, Yang Chunxiang
1994, 18(S1): 28-32.
With the powerful multidetector system of In-beam γ-ray experiment,γ-lines following the β+/EC decay of 198Bi nucleus have been investigated using comprehensive (γ-γ-t) coincidences in in-beam conditions.Five new transitions of 198Pb were observed and eight energy levels were established.
Study of Topography Changes Induced by 150keV Argon Ion Bombardment of Amorphous Alloys
Hou Mingdong, Liu Changlong, Quan Mingxiu, Sun Wensheng
1994, 18(S1): 33-38.
Amorphous alloys Fe39NiMo2Si12B8,Fe40Ni40Si12B8,Fe39Ni39V2Si12B8,Fe77Cr2Si5B16 and Fe78Si10B12 were bombarded with 15keV argon ions.The effects of the total dose on surface damage of amorphous alloys have been investigated using a scanning electron microscopc.At low doses,blisters and/or craters are formed.With increasing the total dose,the blisters or craters are eroded and the pinholes are formed.At higher doses,sputtering is the dominant damage process.Sputtering induces the development of porous structures.The structures obtained after higher doses depend strongly on target material.
Radioactive Ion Beams at HIRFL
Zhan Wenlong, Guo Zhongyan, Zhou Jianqu, Yin Quanmin, Zhao Youxiong, Wang Jinchuan, Xi Hongfei, Wang Yifang, Luo Yongfeng
1994, 18(S1): 39-46.
At the first stage the Radioactive Ions Beam Line in Lanzhou (RIBLL) is a Projectile Fragmentation (PF) type RNB facility,in which neutron-rich and protonrich RNB are produced by means of the energitic projectile fragmentation at around 0°.The mechanisms of RNB production,seperation,transportation and identification are introduced; the stucture and characteristics of this system are describted.The results of test run are also reported in this paper.
The Multichannel Fission Model Applied to 235U(n,f)
Fan Tieshuan, Hu Jimin, Bao Shanglian
1994, 18(S1): 47-55.
In the frame of the multichannel fission model with the random neck rupture,the fragment yield and total kinetic energy distributions of the neutron induced 235U(n,f) fission covering the incident neutron energy range from 0 to 6MeV are calculated.The change of channel probabilities with the neutron incident energy is obtained by fitting experimental data.The theoretical results are in accord with the experimental data.
In-medium N-N Elastic Cross Section
Mao Guangjun, Li Zhuxia, Zhuo Yizhong, Han Yinlu, Yu Ziqiang
1994, 18(S1): 56-63.
The momentum- and density-dependent coupling constants for scalar and vector fields are proposed.The saturation properties of the nuclear matter,the experimantal data of the energy-dependent optical potential and the mean free path in nuclei can be reproduced simultaneously.The in-medium n-n elastic cross section has been calculated for different densities and energies.The results show that it is important to take the density dependence of the n-n cross section into account.
Multifragmentation in Heavy Ion Collisions
Zhang Shaoguang, Liu Jianye
1994, 18(S1): 64-70.
The QMD model is coupled with the restructured aggregation model(RMA),which is named as improved QMD (IQMD).By IQMD,the influences of the medium effect,momentum dependent interaction and the equations of state on the multifragmention process at different beam energies have been investigated.
Channel Theory of Fission with Diffusive Dynamics
Wang Shunuan
1994, 18(S1): 71-74.
The channel theory of fission with diffusive dynamics is proposed based on Borh channel theory of fission and Fokker-Planck equation.
The Structure of 208Tl
Gu Jinnan
1994, 18(S1): 75-80.
The Low-lying states and electromagnetic transitions of 208Tl has been calculated in the framework of large basis shell model.The theoretical results are in good agreement with the experimental data.It shows that MSDI may be used nicely to describe the properties of 208Tl.The logft1/2 values of 208Hg are estimated.
Study of Soft Quadrupole Excitation in Nucleus 11Li within Test Particle Method
Cai Yanhuang
1994, 18(S1): 81-86.
The quadrupole excitations in nucleus 11Li have been studied within the nuclear Vlasov equation approach.The classical phase space distribution function is given by the test particle propagation method.A soft mode of quadrupole excitation located around 2MeV is found.The total percent of E2 energy-Weighted sum rule (EWSR) exhausted in this soft resonance region is very sensitive to the extension of neutron halo in nucleus 11Li.The results compared with other recent calculations are analyzed.
EFR-DWBA Analysis of α-Particle Induced Reactions on Nuclei 10,11B at 31.2MeV
Li Panlin, Li Zhiliang, Kong Xiangjing
1994, 18(S1): 87-94.
The data of α-particle induced reactions on 10,11B at 31.2MeV have been analyzed by using the programm MARS-SATURN EFR-DWBA method.The results are shown that direct stripping reactions are the main reaction mechanism in most of 10,11B(α,x)*C reactions.However,there is direct stripping plus heavy particle stripping in the reactions 11B(α,d0)13C and 11B(α,p0)14C.In addition,the mechanism of compound nucleus seems to be taken into account for the peak of intermediate angular region in the reaction 11B(α,p0)14C.Finally,the agreement between theoretical calculation and experimental data is satisfactory in those reactions:10B(α,p0)13C,10B(α,d1)12C* and 11B(α,d0)13C.
The Energy Storage and the Intrinsic Properties of Nucleus in HIC at Intermediate Energies
Zeng Xianghua, Ge Lingxiao
1994, 18(S1): 95-100.
The relation between the intrinsic properties of nucleus and the energy storage in HIC at intermediate energies has been discussed on the basis of BUU model.The calculated results show that the effective mass m*/m influences strongly the energy storage and the thermalization process,and the effect of incompressibility coefficient K on the energy storage is not strong than that of m*/m.