Light Particle and Complex Fragments Emission from 12C Induced Reactions on 58Ni,64Ni at E/A=46.2MeV

Energy spectra of light charged particles and complex fragments emitted in the interaction of 46.2MeV/u ¹²C with different target ⁵⁸Ni,⁶⁴Ni,¹²C,¹⁹⁷Au and ²⁰⁹Bi have been measured by telescopes,consisting of CsI(Tl) and surface barrier detector stacks.These telescopes for light charged particles and complex fragments have good energy resolution and mass identification.The inclusive data have been analysed within a moving source parametrization.The complex fragment yields from different targets have been compared at several angles.The systematic variation of deduced isotope yields ratios with different reaction systems is used to detemine the N/Z degree of freedom equilibration of the system achieved.     

About Three-Body Exit Channel in the Reaction 12C+16O at EL(16O)=56MeV

Three-body exit channel in the reaction ¹²C+¹⁶O at 56MeV has been studied by using measurement of the coincidence between the two changed particles.The projected spectra of the coinsidence between the two α-particles shows that the channel α+²⁴Mg is the main intermediate process of three-body exit channel α₁+α₂+²⁰Ne in the reaction ¹²C+¹⁶O at 56MeV.The analysis of theoretical calculation showed that the sum of sequential decay and statistical break-up fit the experimental spectra satisfactorily.     

QUASI-ELASTIC AND DEEP INELASTIC REACTIONS OF 12C ON 27Al

Quasi-elastic and deep inelastic reactions of 71.5 MeV ¹²C ions on a ²⁷Al target are measured, ΔE-E telescope is used to identify the reaction products. The energy spectra, angular distributions and contour products in the E-θ plane are obtained and discussed.     

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.     

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.     

Evaporation of Intermediate-Mass Fragments From Hot-Nuclei in Reaction 40Ar+159Tb at 25MeV/u

The inclusive energy spectra of intermediate-mass fragments(IMF)(3≤Z≤9)have been measured in the range from 20°to 155°for ⁴⁰Ar+¹⁵⁹Tb reaction at 25MeV/u.At backward angles,the spectra of IMF show a characteristic of statistic evaporation and can be well fitted by a moving source with same parameters.The obtained source velocity and temperature are in agreement with the corresponding values of hot nuclei produced in an incomplete-fusion process.Therefore,it seems that there IMF are statistically evaporated from a same source.The experimental results have for compared with the predictions of the statistical model using GEMINI code.     

INFLUENCE OF THE NEUTRON NUMBER OF TARGET NUCLEUS ON CROSS SECTIONS OF PARTICLES EMISSION IN 12C+112,124Sn

The energy spectra and angular distributions of Li, Be, B particles emitted from the ¹²C+¹¹²Sn and ¹²C+¹²⁴Sn reactions at E_L=70.0MeV are measured. The angular distributions of the Li, Be, and B particles are found to be peaked around the grazing angle, without any forward peaked component.
The experimental results also showed that the cross section for emission is larger in ¹²C+¹¹²Sn reaction than that in ¹²C+¹²⁴Sn reaction, in contrast with the cross sections for Li, Be and B emissions. The indicates the effect of the neutron number of the target nucleus on the emission probability.     

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.     

Stady on the Energy Spectra of fp Odd A Nuclei 47Ti,47V,49Cr With PDHF Method

The approximate angular momentum projected Hartree-Fock(PDHF)method is used to some odd-A nuclei in the fp shell:⁴⁷Ti,⁴⁷V,⁴⁷Cr,⁴⁹Cr.Their energy spectra are calculated and compared with the experimental data.The results are fairly satisfactory.In addition,the characteristics of those spectra are analyzed with the particle-rotor model.It is found that those spectra possess the properties of the no alignment limit Spectra.     

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.     

THE MEASUREMENT OF LIGHT PARTICLE EMISSION FROM 12C+159Tb,Ag AND 89Y REACTIONS

The energy spectra and angular distributions of α-particle emitted from ¹²C-induced reactions with ¹⁵⁹Tb, Ag and ⁸⁹Y targets have been measured. Meanwhile the emitted deutron's angular distributions with ¹⁵⁹Tb and ⁸⁹Y targets and proton's with ⁸⁹Y target have been also obtained.
The α-energy spectra associated with mentioned reactions have bell-like shape with probable energy near coulomb barrier. However, the main characteristic of the α-angular distribution for ¹⁵⁹Tb and Ag targets is peaked at or near the grazing angles. For the case of ⁸⁹Y target, α-differential cross-sections monotonically decrease with angles beyond 40º. The angular distributions of potons and deutrons nearly decrease exponentially.
The measured α-angular distributions could be divided into two components, one coming from α-evaporation is isotropic, another is anisotropic. The anisotropic component may be explained incomplete-fusion process in which the cross-section can be reproduced by a "Sum-Rule Model" due to J.Wliczynski.
In order to explain the anisotropic component of emitted α-particle, we propose in complete fusion model with a strong-damped sticking rotation, in which the rotation angles and interaction time of the composite system are also estimated.     

THE MASSIVE TRANSFER IN 12C+197Au REACTION

In this paper, we present energy spectra and angular distributions for the α-par-ticles emitted in the reaction of ¹²C+¹⁹⁷Au at 64 and 67 MeV and for α, Be and B emittedin the reaction at 71.5 MeV. The most-probable energles of the variousproducts emittedin this reaction decrease.with decreasing incident energy. The angular distributions peak near grazing angle.The peak position of the angular distributions shift from--80°to--120°while the projec-tile energy decreases from 71.5 MeV to 64 MeV. These all show the features of the transferreaction. The ⁶Li product also has been measured and the ⁸Be particle emitted from thisreaction was detected at 90°to the beam direction using α-α coincident technique at 71.5MeV. The coross section of the ³Be is only few percent at the same angle.     

STUDY OF DEEP INELASTIC COLLISION 12C+27Al AT ENERGY 61.8MeV

By using ΔE-E telescope and the time of flight detector, the energy spectra of products between ⁶Li and ¹⁶O were measured for the reaction ¹²C+²⁷Al, at 61.8MeV. The contour plots of differential cross section in c.m. system and the angular distributions of emitted fragments were obtained. The calculated values of fully relaxed energies in deep inelastic collistions agree with the experimental values. The mean interaction time of di-nuclear system was estimated as from 1×10^－21s to 1.4×10^－22s     

A Comparison Between Two Different Optical Potentials for the 3He+ 12C Scattering at the Energy 72MeV

Through the analysis of the ³He elastic scattering on the ¹²C nucleus, two different folded optical potentials, one is constructed based on the α-particle model of the ¹²C nucleus, another is constructed based on the nucleon component model of ¹²C, are compared. The comparison shows that the former optical potential has some advantages.     

Study of Ternary Fission Produced in 12C Bombarding 209Bi Target with Medium Energy

Alternative layers of target material,which were prepared by evaporating ²⁰⁹Bi on the surface of mica foils,were irradiated with ¹²C ions.Ternary fission events in which three fragments of comparable mass were produced in 2525－47.5MeV/A ¹²C+²⁰⁹Bi reaction,were recorded by the mica detectors with 2π geometry.The observed probability ratio of ternary fission relative to binary fission in 2π geometry was modified to 4π geometry spatial in terms of the Monte Carlo method.The values of ratioes increase with the bombarding energy,and are compared with the calculation result of the cascade fission model.     

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.     

SYMMETRY OF THE ROTATION+VIBRATION SPECTRA FOR NUCLEAR MOLECULE 12C+12C

The rotation-vibration spectra of nuclear molecule ¹²C+¹²C is chassified by the irreducible representations of group U(5). It is shown that the symmetry of rotation-vibration levels of nuclear molecule ¹²C+¹²C are discribed by means of dynamical symmetry U(5)U(4)O(4)O(3).     

Excitation Function for 12C+12C Elastic Scattering

An energy dependent optical potential for ¹²C+¹²C system is established based on the analyses of the angular distributions of the elastic scattering in the energy range of 70-160MeV. This potential can well reproduce the excitation function for 12C+12C elastic scattering in the same energy range.     

Quasi-Elastic Scattering of 16C from 12C at 47.5 MeV/Nucleon

Differential cross sections for the quasi-elastic scattering of^16 C at 47.5 MeV/nucleon from ^12 C target are measured.Coupled-channels calculations are carried out and the optical potential parameters are obtained by fitting the experimental angular distribution.     

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.