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.     

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.     

Fragmentation Cross Sections of 12C on Different Targets at Beam Energies from 50 to 100MeV/Nucleon

The fragmentation cross sections of reactions ^12C＋^2H, ^12C, ^14N, ^16O at beam energies from 50 to 100 MeV/nucleon are investigated using the isospin-dependent Boltzmann-Langevin equation model. It is found that fragment species increase approximately with the increasing target mass. The fragment species and some fragments production cross sections in reactions of ^12C＋^12C, ^14N, ^16O show an obvious variation at the beam energies from 50 to 80 MeV/nucleon. However the calculated fragment production cross sections do not change much when the incident energy increases from 80 to 100 MeV/nucleon.     

STUDY ON BINDING PROBLEM OF Δ(1232) IN NUCLEI WITH HARTREE-FOCK METHOD

The binding problem of isobar Δ(1232) in ⁴He ¹²C and ¹⁶O systems is studied in detail by Hartree-Fock method. The OBEP is used for the nucleon-nucleon potential and the nucleon-Δ(1232) interaction. The calculated results show that Δ(1232) can be bound only in ⁴He and not in ¹²C and ¹⁶O systems.     

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.     

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.     

π-NUCLEAR DOUBLE CHARGE EXCHANGE REACTION AND NUCLEAR STRUCTURE

Using Glauber's multiple scattering theory, and using coherent fluctuation nuclearmodel, the double charge exchange (DEC) reaction cross sections for πon ¹⁶O and ¹⁸Ohave been calculated. The calculated values of the ratio of σ(¹⁸O(π⁺,π^-)¹⁸Ne)_g.s. toσ(¹⁶O(π⁺,π^-)¹⁶Ne)_g.s. fit the experimental data quite well. Just as predicted by ourcalculation, the angular distribution of ¹⁸O(π⁺,π^-)¹⁸Ne_g.s. in a recent experiment,exhibits an evident dip around 23°.     

BOUND STATES OF ETA-24Mg AND ETA-32S

The Eta-²⁴Mg mesic mucleus and the Eta-³²S mesic nucleus are considered as the ¹²C-Eta-¹²C and ¹⁶O-Eta-¹⁶O three body systems respectively.With the separable potentials which include only S-wave Eta-¹²C and Eta-¹³O interadtions as the effective interactions,the Schrodinger equa tions of the systems are solved in the Born-Oppenheimer approximation.The two-center problems are solved exactly first,and then the binding-energies of Eta-²⁴Mg and Eta-³²S are calculated.The calculated results are satisfactory.     

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.     

Band Structure in Doubly Odd 170Ta

High spin states in ¹⁷⁰Ta have been studied via ¹⁵⁹Tb(¹⁶O,5nγ)¹⁷⁰Ta reaction at 105MeV.Three rotational bands are observed,among which one coupled band and an unfavored ΔI=2 E2 squence are newly found in this owrk.The possible quasiparticle configurations of these bands are discussed.     

An Investigation of Relativistic Microscopic Optical Potential in Terms of Relativistic Brueckner-Bethe-Goldstone Equation

Relativistic microscopic optical potential of nucleon-nucleus is derived from the relativistic Brueckner-Bethe-Goldstone (RBBG) equation.The complex effective mass of a nucleon is determined by a fit to 200MeV p-⁴⁰Ca scattering data.The relativistic microscopic optical potentials with this effective mass are obtained from RBBG for p-¹⁶O,⁴⁰Ca,⁹⁰Zr and ²⁰⁸Pb scattering in energy range from 160 to 180MeV.The microscopic optical potential is used to study the proton-⁴⁰Ca scattering problem at 200MeV.The results,such as defferential cross section,analyzing power and spin rotation function are compared with those calculated from phenomenological relativistic optical potential.     

Effects of Helium and Oxygen Common Implantation in Silicon Wafer

Defect engineering for SiO2 precipitation is investigated using He-ion implantation as the first stage of separation by implanted oxygen （SIMOX）. Cavities axe created in Si by implantation with helium ions. After thermal annealing at different temperatures, the sample is implanted with 120 keV 8.0 ×1016 cm 2 0 ions. The Q ion energy is chosen such that the peak of the concentration distribution is centred at the cavity band. For comparison, another sample is implanted with O ions alone. Cross-sectionM transmission electron microscopy （XTEM）, Fourier transform infrared absorbance spectrometry （FTIR） and atomic force microscopy （AFM） measurements are used to investigate the samples. The results show that a narrow nano-cavity layer is found to be excellent nucleation sites that effectively assisted SiO2 formation and released crystal lattice strain associated with silicon oxidation.     

Lifetime Measurements of the States Around the Backbend in 126Ba

The high spin states in ¹²⁶Ba were populated by means of the reaction ¹¹⁶Sn (¹⁶O,2p4n)¹²⁶Ba at the beam energy of 73MeV. Lifetimes of the states around the backbend in the yeast band were measured by using the Doppler shift attenuation method. The corresponding normalized B(E2) values are pronouncedly reduced for the 10⁺ and 12⁺ states. The experimental results are compared with the theoretical predictions of the particle-rotor model.     

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     

Production of Helium Projectile Fragments in 16O-Emulsion Collisions at 60 A GeV

Production of helium projectile fragments in ¹⁶O-emulsion interactions at 60 A GeV is investigated. The total charge changing and partial production cross-sections are measured experimentally on the basis of helium multiplicity. The multiplicity distribution of helium projectile fragments obeys a KNO scaling. In the peripheral collision of ¹⁶O at 60 A GeV in nuclear emulsion, the production of target fragments depends on the multiplicity of helium projectile fragments linearly. The averge multiplicity of target fragments decreases with the increasing of the number of helium projectile fragments which can be well expliained by the model of participant-spectator (the nuclear geometric model) of nucleus-nucleus interactions.     

STUDY OF ANGULAR DISTRIBUTION OF THE SCATTERING OF 31.2 MeV α PARTICLE BY THE NUCLEUS 10.11B

Angular distribution of the scattering of 31.2 MeV-α-particle by the nucleus ^10,11B is measured. Our results show that there is anomalous phenomenon in the case of ¹⁰B but there is not in ¹¹B. Calculations and analysis are made with the optical model adding the Regge-Pole model. The results show that for the nucleus of 1p-shell, such as α+¹⁶O, the result of the calculation agrees very well with the experimental measurements but it fails in α+¹⁰B. As to the analysis with the double v-power optieal model for α+¹⁶O, the agreement is somewhat a little worse than the former's and the result for α+¹⁰B agrees only qualitatively with the experimental measurement. It is well known that the analysis with these models for α+⁴⁰Ca agrees very well with the experimental data. Thus we may come to the conclusion that the mechanism of ALAS of the nucleus of 2s-1d shell is different from that of 1p-shell, and the mechanisms of ALAS of the nuclei of 1p-shell are also different.     

EXCITATION FUNCTION FOR ELASTIC COLLISION BETWEEN 4n NUCLEI

Resonant structures appeared in the excitation functions for the ¹⁶O+²⁰Ne elastic scattering have been studied by using the nuclear molecular orbital theory.The theoretical results agree well with the experimental data.     

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.