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.     

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.     

THE FINE STRUCTURE OF 208Pb 1+ STATES

The energy levels and transition probabilities B（M1） of the ²⁰⁸Pb 1⁺ states are calculated using the matrix diagonalized method in which the （1p 1h） configurations are coupled to collective octupole phonons. Calculated results show that the fine structure of the ²⁰⁸Pb giant magnectic resonance depends rather strongly on the phononparticle coupling constant.     

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     

THE MEASUREMENT OF THE EXCITATION FUNCTIONS OF ISOTOPES OF Fr AND At,PRODUCED IN THE BOMBARDMENT OF 12C ON 209Bi

Excitation functions for Fr and At isotopes produced in ¹²C on ²⁰⁹Bi had been measured in the energy range 60—72 MeV. It was quite obvious that ²¹³Fr and ²¹⁴Fr were formed by the reactions ²⁰⁹Bi (¹²C,4n) ²¹⁷Ac and ²⁰⁹Bi (¹²C,3n) ²¹⁸Ac following the a decay of the Ac isotopes respectively, and ^214mFr was produced probably by compound nucleus evaporation of neutrons and an α particle, i.e. (¹²C, α 3n). ²¹¹At was mainly contributed by a multi-nucleon transfer reaction （e.g. ⁸Be transfer）. The experimental data for neutron evaporation reaction were fitted by the Jackson formula.     

A SEMI-CLASSICAL ANALYSIS ON THE REACTION 12C+209Bi AT BOMBARDING ENERGIES SLIGHTLY ABOVE THE COULOMB BARRIER

For reactions induced by light heavy ion such as ¹²C, at bombarding energy slightly above the coulomb barrier, using semi-classical theory, neglecting macroscopic frictional force, the reaction mechnisms are sorted by the orbital angular momentum of the entrance channel from the classical deflection functions fitting elastic scattering. Moreover, inserting a transfer probability factor representing the Q-Window effect into the semi-classical angular distribution formula of Kalinkin and Grabowski, we obtain a formula for the differential cross-section per unit energy interval. The calculated results, including the elastic scattering angular distributions, energy spectrum and angular distributions of emitted α-particles in quasi-elastic process, complete fusion cross-section, fusion-fission cross-sections and the exitation functions of evaporated neutron, agree with the experimental data on the reaction ¹²C+²⁰⁹Bi reported by our Institute.     

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.     

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.     

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 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.     

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.     

EFFECT OF MULTIPOLE VIBRATION ON M1 TRANSITION OF 1+ STATES IN 208Pb

In this paper, the generate coordinator method (GCM) is applied to study the effect of multipole vibration on M1 transition of 1⁺ states in ²⁰⁸Pb. The calculation shows that coupling between 3^－ collective state and (1p1h) gives much more effect than the coupling effect of 2⁺ state with (1p1h).     

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 Spin Effect of Antiproton-Nucleus Inelastic Collison

If the antiproton optical potential is inclusive of the spin orbit interaction term,the A(p,p)A* inelastic scattering not only can excited the normal parity states,but also can excited the abnormal parity states.There are also induced the polarization P_f(θ) at the inelastic scattering.In the framework of DWIA,we derived the inelastic scattering cross section (dσ/dΩ)_f,i,and polarization P_f(θ),and calculated the (dσ/dΩ)_f,i, and P_f(θ) for ¹²C(p,p)¹²C* with 2⁺,3^－ and 1⁺ states at antiproton energies of 46.8 and 179.7MeV.They fited experiment data quite well.Due to the abnormal partity states in the inelastic process have been measured,the spin orbit term can not be neglect.     

INTERACTING BOSON MODEL FOR EVEN-EVEN NUCLEI POSSESSED OF 1+ AND 3+ BANDS IN THE ROTATIONAL RIGION

On the bases of s, d IBM, octupole states are taken into account and the two-quasiparticle excitation is treated as boson-like in the SU(3) limit. The energy spectra are obtained analytically and the nondegenerated 1⁺ and 3⁺ bands are also reproduced. The calculated spectra of eight nuclei, which possess with 1⁺ or 3⁺ bands in their energy spectra in the rotational rigion, agree with the experimental ones fairly good.     

The Cross Section Fluctuation of the Isotope Projectile-Like Fragments in the Dissipative Process of Reaction 19F+51V

By using a detection system combining Time-of-Flight(TOF)method with(△E-E)technique,the excitation functions,the dependence of energy coherence widthΓon product mass A and the dependence of Γon the degree of freedom of neutron excess N/Z for some elements and their isotope products in the dissipative process of reaction ¹⁹F+⁵¹V at energies from 102.25MeV to 109.50 MeV(in 250 keV steps)were presented and discussed for the first time.     

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.     

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.     

20Ne+12C System and the Double-Alpha Transfer effect for a Deep Optical Potential

In this paper,the basic features exhibited by ²⁰Ne+¹²C system are analyzed and the excitation functions and the angular distributions of the ²⁰Ne+¹²C elastic scattering are well reproduced on the basis of the nuclear molecular orbital theory.The results show that the double-alpha transfer effect for a deep optical potential is responsible for the above difference in the elastic scattering excitation functions between these two systems.     

THE SHAPE ISOMER 240mPu

By means of an annular mica detector, the half-life and excitation function had been measured for the shape isomer ^240mPu produced in the reaction ²³⁸U （α, 2n）. A value of 3.5±0.5 ns was obtained for the half-life of ^240mPu. The shape isomer excitation energy Bi was found to be 3.2±0.5 MeV.