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1.
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.  相似文献   

2.
Using the HFB cranking model, the RAL effect of g9/2 proton pair and neutron pair for three forking phenomenon in 68Ge is studied. Calculations show that two backbending of three forking in 68Ge are mainly caused by rotation alignment of g9/2 proton pair and neutron pair.  相似文献   

3.
The interacting boson model-3(IBM-3) has been used to study the low-energy level structure and electromagnetic transitions of 68Ge nucleus. The main components of the wave function for some states are also analyzed respectively. The theoretical calculations are in agreement with experimental data, and the 68Ge is in transition from U(5) to SU(3).  相似文献   

4.
As an extension of radioactive ion beam physics, the research on isospin dependent properties of hot nuclei has increasingly attracted considerable interest. The isospin effect on the decay of hot nuclei in reactions 35MeV/u 40Ar+112Sn/124Sn has been investigared. It is concluded that due to Coulomb repulsion and instability, proton-rich hot nuclei probably emit prides such as a with high energy to increase their neutron-proton ratio. Moreover, the decay chain for those particles is seemingly long and the emission Probability is high. Thus, the conventional observations, for instance, the ‘slope temperature’ extracted from energy spectrum, may very appreciably with the measured particles.  相似文献   

5.
Isotope ratios,defined as the yield ratio of two isotopes with the same charge,were analyzed as a function of kinetic energy of outgoing particles at 20° in the reactions of 40Ar+112,124Sn and 5°in36Ar+112,124Sn at incident energy of 35MeV/u. Isotope ratios between the neutron-deficient isotopes and stable isotope increase with kinetic energy,while those between the neutron rich isotopes and stable isotope decrease. This different behavior was observed similar for both 112Sn and 124Sn targets. The isotope ratios show rather obvious target dependence at 20° and little target dependence at 5°. As the outgoing energy getting down,the N/Z ratio of the fragmentation products at 5° diverts gradually from the N/Z ratio of the projectile to that of the system. These observations indicate that the isospin degree of freedom does not reach complete equilibrium in the peripheral or semi-peripheral collision at this bombarding energy.  相似文献   

6.
An array of 13 detector telescopes has been used for detecting small-angle particle-particle correlations in the reactions 40Ar+112,124Sn at 30MeV/u. The α-α correlation functions were extracted from two-particle coincident events. A three-body trajectory code MENEKA was used to calculate the background correlation function. The detection efficiency was calculated by using the Monte-Carlo method. After subtracting the background correlation and making the detection efficiency correction, the temperatures of 4.18±0.25 0.21 MeV and 4.10±0.22 0.20MeV are obtained from relative populations of 8Be states for the reaction systems with different isospin,40Ar+112Sn and 40Ar+124Sn, respectively. From the relationship between the state population temperature and outgoing particle energies, it is found that the emission temperature decreases with increase of the particle energies for both studied reaction systems. For the neutron deficient system 40Ar+112Sn the emission temperature is 5.13±0.30 0.26MeV for the lower emitting particle energies and 3.87±0.37 0.29MeV for the higher emitting particle energies. And for the neutron rich system 40Ar+124Sn the emission temperature is 5.39±0.30 0.26MeV for the lower emitting particle energies and 3.32± 0.28 0.23MeV for the higher emitting particle energies. This kind of isospin dependence is discussed.  相似文献   

7.
The interacting boson model-3(IBM-3) has been used to study the energy levels and electromagnetic transitions for the nucleus 34 S.The main components of the wave function,isoscalar and isovector parts in the M1 and E2 transitions for low-lying states have been investigated.According to this study,the theoretical calculations are in agreement with experimental data,and the nucleus 34 S is in transition from U(5) to S U(3).  相似文献   

8.
The high-spin states of 159Lu were populated by fusion-evaporation reaction 144Sm (19F, 4n) with beam energy 106 MeV. A new level scheme was established, which consists of the yrast band with negative parity, the octupole vibration band based on the states and quasipartical band with positive parity. The high spin states of 159Lu were discussed by systemic characteristics.  相似文献   

9.
High-spin states in 139Nd nucleus have been reinvestigated with the reaction 128Te (16O, 5n) at a beam energy of 90 MeV. The level scheme has been expanded with spin up to 47/2 h. At the low spin states, the yrast collective structure built on the νh11 / 2-1 multiplet shows a transitional shape with γ≈32° according to calculations of the triaxial rotor-plus-particle model. Three collective oblate bands with γ~-60° at the high spin states were identified for the first time. A band crossing is observed around hω~0.4 MeV in one oblate band based on the 25/2 level.  相似文献   

10.
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.  相似文献   

11.
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.  相似文献   

12.
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.  相似文献   

13.
叶巍  吴锋  杨宏伟 《中国物理 C》2008,32(10):816-819
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.  相似文献   

14.
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.  相似文献   

15.
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.  相似文献   

16.
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.  相似文献   

17.
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.  相似文献   

18.
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.  相似文献   

19.
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.  相似文献   

20.
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.  相似文献   

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