Angular Distribution of the 12C(6He, 7Li)11B Reaction

Angular distribution of the ¹²C(⁶He,⁷Li)¹¹B transfer reaction is measured with a secondary ⁶He beam of 36.4MeV for the first time. The experimental angular distribution is well reproduced by the distorted-wave Born approximation (DWBA) calculation. The success of the present experiment shows that it is feasible to measure one-nucleon transfer reaction on a light nucleus target with the secondary beam facility of the HI-13 tandem accelerator at China Institute of Atomic Energy (CIAE), Beijing.     

Radial Expansion Flow in Reactions of 40Ca+58Fe and 40Ca+58Ni

By means of using an isospin-dependent Boltzmann-Langevin equation which includes isospin-dependent symmetry energy, Coulomb energy, isospin-dependent nucleon-nucleon cross sections, Pauli blocking, and initialization, the radial expansion flow of reaction systems ⁴⁰Ca+⁵⁸Ni and ⁴⁰Ca+⁵⁸Fe at 53, 100, 150, and 200 MeV/u in the central collisions were studied. It has shown that the more neutron rich system exhibits smaller radial expansion flow. It was found that the neutron rich system had smaller threshold energy which may provide a new method to determine the isospin dependent nuclear equation of state from calculated result and linear fitting result.     

A Three-Body Model of 11Li,14Be and 17B

The nuclei ¹¹Li,¹⁴Be and ¹⁷B are considered as three-body systems composed of the N=2Z core and two outside neutrons.The core-neutron and neutronneutron interactions are assumed to be the attractive exponential potentials.It has been shown that the three-body system can have a bound state although any two constituents of the system cannot have a bound state. The experimental data of the binding energy and extraordinarily large matter root-mean-square radius can be explained in the frame of the three-body model.     

Optical Potential Parameters for Halo Nucleus System ^6He＋^12C from Transfer Reaction ^11B（^7Li, ^6He）^12C

The optical potential parameters for the halo nucleus system ^6He＋^12C are extracted from fits to the measured angular distributions of ^11B（^7Li, ^6He）12C reaction at energies of 18.3 and 28.3MeV with distorted-wave Born approximation analysis. The characters of the obtained optical potentiM parameters are basically consistent with the results extracted from the fits to the elastic-scattering angular distributions in the literature.     

ON THE TRANSFER MECHANISM OF 16O+24Mg AND 20Ne+24Mg ELASTIC SCATTERING

The mechanism of transfering a cluster of nucleons between two colliding nuclei is considered to explain the backward angle oscillatory rise in the differential cross section of the elastic scattering between certain nuclei, such as ¹⁶O+²⁴Mg or ²⁰Ne+²⁴Mg. The nuclear molecular orbit approximation theory is applied. For one-step transfer, if the parameter involved is assumed to be adjustable, the numerical calculations can be made to fit the experimental results naturally.     

Further Studies on Halo Nuclei 11Li,14Be and 17B

Based on the three-body model with Yukawa interactions,the halo nuclei ¹¹Li,¹⁴Be and ¹⁷B are further studied by the variation calculation.An analytical expression for the density distribution of the halo neutron is given.The theoretical resultsagree with the recent experimental data.     

MEASUREMENT OF COMPLETE FUSION CROSS SECTION OF 12C+159Tb,12C+165Ho

Complete fusion cross sections have been measured for ¹²C+¹⁵⁹Tb and ¹²C+¹⁶⁵Ho reactions by using K-X rays of evaporation residues with Si(Li)spectrometer.The half-lives of evaporation residues and its yield distributions as a function of incident energy have also been obtained.The experimental values for the complete fusion cross section were compared with the theoretical ones.     

Langevin study of neutron emission in the reactions 16O+181Ta and 19F+178Hf

The pre-scission neutrons measured in the reactions ¹⁶O+¹⁸¹Ta and ¹⁹F+¹⁷⁸Hf are studied via a Langevin equation coupled with a statistical decay model. We find that because of the mass asymmetry of different entrance channels, the spin distributions of compound nuclei would be different, consequently, the measured neutrons in these two reactions would also different. This means that the entrance channel will affect the particle emission in the fission process of hot nuclei.     

9,11Be+209Bi近垒熔合

阐述了9,11Be+209Bi近垒熔合反应研究的意义,给出实验结果并讨论弹核破裂对近垒熔合反应截面的影响. The purpose and importance of the study of 9,11Be+209Bi near barrier fusion were reviewed. The breakup effects of the halo nuclei on fusion were discussed and compared with the experimental results of 9,11Be+209Bi systems.     

Measurement of Angular Distributions for Elastic Scattering of 16O+94Zr and 16O+116Sn Reactions

The angular distributions for elatic scattering of the two systems,¹⁶O+⁹⁴Zr at energies 52,57,59,62,72,82 and 92 MeV and ¹⁶O+¹¹⁶Sn at energies 57,59,62,67,72,82 and 92 MeV have been measured.The scattered ions were datected by the Beijing Q3D magnetic spectrometer and its heavy ion focal plane detector.The optical model analysis of the data was made with the Coupled Channels code ECIS, and the optical potential parameters have been obtained by fitting the data.Within the limited data,the phenomenon of the ‘threshold anomaly’is observed.     

SINGLE PROTON TRANSFER REACTION INDUCED BY HEAVY ION 40Ar(11B, 10Be)41K

The angular distribution has been measured for elastic scattering on ⁴⁰Ar with ¹¹B and for the single proton transfer reaction ⁴⁰Ar(¹¹B, ¹⁰Be)⁴¹K at the incident beam energy of 50 MeV. The elastic scattering cross section has been fitted in terms of the optical model. The EFR-DWBA aproach with recoil effect has been used to analyze the differential cross section. The spectroscopic factor was extracted.     

THE MEASUREMENT OF COMPLETE FUSION CROSS-SECTIONS FOR THE REACTIONS 12C+27Al, 12C+209Bi AND 14N+Pb

Mica track detectors were used for the measurement of evaporation residues and fission fragments of compound nuclei formed in ¹²C+²⁷Al, ¹²C+²⁰⁹Bi and ¹⁴N+Pb reactions. The complete fusion cross-sections and excitation functions were then obtained. By using the sharp cut-off model approximation, the values of the critical angular momenta were extracted from the complete fusion cross-sections. The results obtained were compared with the calculations based on current theories for critical angular momentum; they were found to agree within experimental uncertainties.     

Research on High Spin States in 68Ge,65Ga and 67Ga

The high spin states in ⁶⁸Ge,⁶⁵Ga and ⁶⁷Ga were studied through in-beam gamma-ray spectroscopy experiment.The reaction ⁴⁶Ti(²⁵Mg,xpxn) was used with beam energy 68MeV.In ⁶⁸Ge the new multiplicity of band structures,the crossing transitions among the bands and a new band with possible big diformation were observed.The experiment results agree with a new microscopic model calculation (EXCITED FED VAMPIR).In ⁶⁵Ga and ⁶⁷Ga a few band structures with strong collectivity were observed and the new level schemes were given.     

ON THE REACTION MECHANISM OF ALPHA TRANSFER REACTION FOR 16O(16O, 12C)20Ne

The oscillatory structure appeared in the differential cross section of the reaction for ¹⁶O(¹⁶O, ¹²C)²⁰Ne may be explained by particle transfer from covalent channel to ionic channel in the nuclear molecular orbital theory.     

RADIOCHEMICAL INVESTIGATION OF MASS DISTRIBUTIONS IN 12C-INDUCED FISSION OF 209Bi AND 238U

The yields of 15 and 17 fission, products have been obtained by radiochemical determinations in ¹²C-induced fission of ²⁰⁹Bi and ²³⁸U respectively. From these data, the mass distributions of fission fragments are calculated based on three different hypotheses for the charge distribution. The results seem to indicate that the hypothesis of equal charge displacement gives the best fit to the Gaussian distribution for the masses of the fission fragments. By comparison with the mass distributions for ²⁰⁹Bi (¹²C, f), ²³⁸U(¹²C, f) and ¹⁹⁷Au(¹²C, f) in our early measurement, we find that for fission parameter Z²/A>37, the width of the mass distributions increases with Z²/A rapidly.     

46.7MeV/u 12C轰击159Tb、197Au和209Bi的裂变测量及分析

用46.7MeV/u~(12)C轰击~(159)Tb、~(197)Au、~(209)Bi,测量关联裂片的速度和角度,研究了线性动量转移(LMT)、质量和出平面角分布,提取了核温度,应用级联两体统计衰变理论进行了拟合与解释,结果表明:在～50MeV/u入射能的中能重离子碰撞中,以非完全熔合方式形成了核温度高达4～5MeV的类复合核,其后通过裂变、蒸发级联统计两体衰变而退激。 The velocities and angles of fission partners emitted from reactions in ~(12)C+~(159)Tb, ~(197)Au,~(209)Bi systems with bombarding energy of 46.7MeV/u are measured. The linear momentum transferfrom projectile to target、mass and out-of-reaction plane angle distributions of fission fragments arestudied, and the temperatures of the target residues are extracted. These results have been explained by statistical binary decay model. It seems that the compound-likesystem with high temperature...     

SYMMETRICAL ANALYSIS OF 9Be AND 12C HYPERNUCLEI

By analyzing the experimental data of the hypernuclei, we propose a hypothesisthat the single baryon binding energy satisfies the SU(3) uintary symmetry. By thissuggestion, some experimental facts in this field can be explained and we also proposethe possibility of the existence of excited states of the hyper [1] nuclei. Some propertiesof this [1] hyper-nuclei is also pointed out.     

Reduced Shell Model Calculations of ^111Sb and ^112Sb

The low-lying states of the mid-heavy odd-even ^111Sb and odd-odd ^112Sb isotopes are calculated for the first time within the shell model framework. The shell model calculations have been carried out within the reduced model space including the single particle orbits ld5/2,097/2, ld3/2, 2Sl/2. We obtain the energy spectra for the ^111Sb and ^112Sb isotopes in the reduced model space by using CD-Bonn two-body effective nucleon-nucleon interaction. The energy spectra are compared to the experimental results to give some discussion about the low-lying states of ^111Sb and ^112Sb.     

EXCITATION FUNCTIONS FOR 16O-INDUCED REACTION ON 115In

Excitation functions for the 21 products of the reaction induced by ¹⁶O on ¹¹⁵In have been determined in an energy region between 51 and 97MeV with nuclear chemistry techniques.The experimental results were compared with those calculated using Alice code and Monte-Carlo analogue.     

Production cross-section of 230Ra in the reaction of 60 MeV/u 18O ions with 238U

A thick natural uranium target was bombarded with a 60 MeV/u ¹⁸O beam. The neutron-rich isotope ²³⁰Ra as the target residue was produced through the multinucleon transfer reaction(²³⁸U-4p-4n). The barium and radium fraction as BaCl₂ precipitate were radiochemically separated first from the mixture of uranium and reaction products. Then, the radium fraction was separated from BaCl₂ precipitate by using cation exchange technique. The γ-ray spectra of the Ra fraction were measured using an HPGe detector. The production cross sections of ²³⁰Ra were obtained by a combination of the radiochemical separation technique and off-line γ-ray spectroscopy. The cross section of ²³⁰Ra has been determined to be 66±20 μb.