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.     

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.     

Complete and Incomplete Fusion in the Reaction of 115In with 16O Ions

Angular distributions and differential range distributions have been measured with nuclear chemistry techniques for 20 target residues from the reactions of ¹¹⁵In with 92 and 71MeV ¹⁶O ions.In terms of the increase of impact parameter,the results indicate continuous evolution of the reaction mechanisms from complete fusion,incomplete fusion to direct reaction involving steadily decreasing transfer of mass and momentum.Contribution of incomplete fusion in ¹⁶O+¹¹⁵In reaction is significantly larger than that in ¹⁶O+⁶⁵Cu reaction.     

ANALYSIS FOR ENERGY SPECTRA OF LIGHT PARTICLES EMITTED FROM 12C+64Ni REACTION

Some experimental results measured for light emission particles with Z≤2 from ¹²C+⁶⁴Ni reaction at E(¹²C)=69, 56MeV are reported. A comparison between moving source model calculation and proton's spectra have been performed. Extracted parameters of the source with faster velocity are agreement with the systematic values found before. The composite particle energy spectra of α, ³He and D were analyzed by coalescence model.     

Optical Potential Parameters of Weakly Bound Nuclear System 17F+13C

Elastic scattering angular distributions of the 14^N＋16^O system and the angular distributions of transfer reaction 16^O（14^N,13^C）17^F at ELab=76.2 MeV and 57 MeV have been measured and calculated by means of the exact finiterange distorted-wave Born approximation with the PTOLEMY code. The optical potential parameters for the weakly bound nuclear system 17^F＋13^C have been deduced and applied to analyse the elastic scattering angular distributions of the similar systems 17^F＋12^C and 17^F＋14^N which are taken from literature. The result shows that the transfer reaction with stable projectile and target combination can be used as an alternative method to extract the optical potential parameters for the weakly bound nuclear system.     

Study of the Reaction Mechanisms Induced by 16O on 64Ni at 96MeV

The angular distributions and Wilczynski plots of emitted fragments from He to O in reaction of ¹⁶O+⁶⁴Ni at 96MeV have been measured.The DIC cross section and intereaction time were obtained.DIC character of the reaction was discussed.The trace which shows that the emitted fragments of He and Li mainly come from the evaporation process of compound nuclei emerged.     

Complete Fusion Excitation Function for the 16O+natS Reaction

The complete fusion excitation function for the ¹⁶O+^natS reaction has been measured in the range of 50-75 MeV with a step of 1.0MeV by using 1a position sensitive △E-E telescope system. The model parameters have been extracted from data analysis.The striking gross structure of the excitation function has been observed. The energies of peaks are at ECM=38,43 and 48 MeV respectively.     

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.     

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.     

Study of Yields for Target Fragments From the Reaction of Iron With 80MeV/u 16O Ions

Produchon yields were determined for 25 abet fragments produced from the reaction of iron with 80 MeV/u ¹⁶O ions. From these data, charge distribution and mass yield distribution have been deduced. The experimental results are compared with those reported from our previous work. It is found that the width parameter σ_z and the most probable charge Z_p of the charge distribution increase slowly with increasing bombarding energy. The mass yield distribution is discussed in terms of the concepts of limiting fragmentation and factorization.     

MEASURMENT OF PROJECTILE-LIKE FRAGMENTS PRODUCED BY 80.6MeV16O ON 27Al

The projectile-like fragments produced by 80.6MeV ¹⁶O on ²⁷Al were measured using the large area position sensitive ionization chamber. The energy spectra, angular distributions, contour plots of d²σ/dΩdE in the E-θ plane of the reaction products from Li to Na and the Z-distribution were obtained. The cross sections of the quasi and deep inelastic scattering were introduced. A brief discussion of the experimental results is also given.     

RESEARCH OF RELAXATION PROCESS INDUCED BY 80.6MeV 16O ON 27Al

The decreasing coefficients of the angular distributions, the charge distributions and the first and second moments of the charge distributions with variation of TKEL are deduced from the results of the measurement of projectile-like fragments produced by 80.6MeV ¹⁶O on ²⁷Al. The relaxation process of this reaction is analysed, the effects of the potential energy surface on the first and recond moments of charge distributions are discussed.     

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     

PION-18O INELASTIC SCATTERING

In the framework of the eikonal form of DWIA and using the transition densitymethod, the differential cross sections for ¹³O (π,π') .¹⁸O^* (2⁺, 1.98 MeV) inelasticscattering at T_π=230 MeV are calculated. The ratios of the integrated cross sectionsfor π^- vs. π⁺ bombardments, are analyzed and the effects of changing the neutron radiusto the differential cross sections are studied as well. Our results fit the data quite well.     

Complete and Incomplete Fusion in the Reaction of 65Cu With 16O Ions

The excitation functions,angular distributions and differential range distributions have been measured for target residues from the reaction of ⁶⁵Cu induced by 45—96MeV ¹⁶O ions with radiochemical techniques.A comparison of the experimental data with Monte-Carlo simulations based on the statistcal model of compound nucleus that the heavy residues are produced by the decay of a compound nucleus formed by complete fusion.Incomplete fusion or massive transfer are the main reaction mechnisms leading to production of the residues with mass number close to that of the target.     

Dispersion Optical Model Analysis of the Neutron Cross Section Anomalv for 16O

The optical model of ¹⁶O is studied based on the dispetsion relation theory at neutron energy up to 20MeV.The total cross section anomaly is removed essendally at low energies for ¹⁶O.     

On the Gross Structure of Fusion Cross Section for 16O+12C System

The gross structure appeared in the total fusion cross section for ¹⁶O+¹²C system is studied by using the LCNO theory and the folding model of the paritydependent potential.The experimental data of the fusion cross section,elastic scattering excitation functions and angular distributions for this system are well explained.     

Fission Fragment Angular Correlation in the Reaction Induced by 84.0MeV 16O Bombarded 238U

Fission fragment angular distribution and angular correlation in the reaction induced by 84.0MeV ¹⁶O bombarded ²³⁸U have been measured by using two position-sensitive PPAC with large area.Transfer fission has been removed from total fission using fission fragment angular correlation technique.The contribution to the total fission cross section arising from transfer is about 10%.The anisotropy of fission fragment for transfer-fission is rather small,thus the removal of the transfer fission has little effect on the total fragment angular distribution.Indeed the anisotropy becomes larger by about 5% and anomalously anisotropies still persist.     

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.     

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.