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1.
We present the elastic scattering of the 6He+208Pb and the 6He+197Au systems at the laboratory energy of E lab=27 MeV within the framework of the McIntyre parametrization, and systematically investigate χ 2/N analysis of both systems to obtain an excellent agreement between the theoretical results and the experimental data. We find large diffusivity parameters indicating long range absorption mechanisms. We also show that both systems lack both the nuclear and the Coulomb rainbow scattering for obtained S-matrix parameters.  相似文献   

2.
The main aim of this work was to describe the reactions of elastic scattering of 16O + 12C over a wide range of energies in an optical model with an l-dependent core. We obtained a value for the compressibility coefficient that agreed with the one found from data on the giant monopole resonance. We considered the elastic transfer of an α particle to reproduce the cross section in the reverse hemisphere.  相似文献   

3.
The 6He + 12C elastic scattering at E = 3.0, 38.3, and 41.6 MeV/nucleon is analyzed using the microscopic model of optical potential. According to this approach, two or three parameters are fitted that renormalize the depth of real, imaginary, and surface parts of the calculated optical potential. In this case, the ambiguity of the obtained sets of fitting parameters remains, but can be reduced by introducing an additional criterion of selection: the dependence of the volume integrals of the optical potential on the energy. The structure of the obtained optical potential, the role of the nuclear medium, the formation of the imaginary part of the optical potential, and the interconnection between the surface potential and the 6He breakup channels are discussed.  相似文献   

4.
At an energy of 25 MeV and in the angular range 7°−175° in the laboratory frame, angular distributions were measured for elastic deuteron scattering on 6Li nuclei and for the respective inelastic-scattering processes accompanied by the transitions to the ground state (1+) of the 6Li nucleus and to its excited state at E x = 2.186 MeV (J π = 3+). The resulting data were analyzed on the basis of the optical model of the nucleus and the coupled-reaction-channel method with allowance for the mechanism of alpha-particle-cluster exchange. It is shown that only upon including, in the analysis, channel coupling and the exchange mechanism can the experimental cross sections for elastic and inelastic scattering be reproduced over the entire range of angles.  相似文献   

5.
The 16O + 28Si reaction has been widely studied both experimentally and theoretically and has been claimed to show indications of chaotic scattering. In order to examine this claim and to address whether reaction models such as the optical one could explain the experimental data, we have analyzed the 16O + 28Si system within the framework of the optical model for ten energies from 29.0 to 45.0 MeV, by using microscopic folded potentials, which are based on M3Y nucleon-nucleon, alpha-alpha effective interactions and a phenomenological shallow potential. All potentials describe the individual angular distributions very well at forward angles. However, they fail to describe the individual angular distributions over the whole angular range up to 180°. Nevertheless, we have been able to explain the experimental data by modifying the surface region of the microscopic real potentials by adding two surface potentials. With these correction potentials, we have obtained very good agreement for the individual angular distributions over the whole angular range for the given energies as well as for the experimental data near the Coulomb barrier. The failure of these optical potentials in explaining the scattering observables of this reaction without corrections puts a question mark on the model and supports the idea of a chaotic behavior. The text was submitted by the authors in English.  相似文献   

6.
Observables of the elastic and inelastic scattering of 800- and 250-MeV protons on 20Ne and 24Mg nuclei were calculated on the basis of the theory of multiple diffractive scattering and the dispersive α-cluster model. The 20Ne and 24Mg nuclei were assumed to consist of a core (16O nucleus) and additional alpha-particle clusters, which could be situated with the highest probability both in the vicinity of the center of mass of the core and outside the core. The multiparticle densities of these nuclei and single-particle nucleon-distribution densities as obtained from the dispersive α-cluster model were used in the calculations. The differential cross sections and polarizations for elastic and inelastic p 20Ne and p 24Mg scattering at the energy of 800 MeV are in better agreement with experimental data than the analogous calculations at the energy of 250 MeV. The spin-rotation functions calculated in the singleparticle approximation for elastic p 20Ne and p 24Mg scattering at these two energy values differ qualitatively from their counterparts calculated on the basis of the dispersive α-cluster model.  相似文献   

7.
8.
Based on experiments on elastic 4Не12С scattering at energies of 1.5–6.5 MeV, a phase analysis is performed and results obtained are compared with the available data. The parameters of 4Не12С interactions are refined to reproduce more correctly the energy of bound energy levels of the 16О nucleus required for calculations of the astrophysical S-factors.  相似文献   

9.
Coupled-channels calculations for the elastic and inelastic scattering of K+ at 715 MeV/c by 6Li and 12C at 635, 715 and 800 kaon Lab momenta have been analysed. The optical potentials of 12C and 6Li are calculated in terms of the alpha-particle and deuteron optical potentials. Good fits to the experimental data and phenomenological calculations are obtained for 6Li and 12C nuclei.  相似文献   

10.
The differential cross section for proton scattering on 15N nuclei is calculated within Glauber diffraction theory at energies of 0.2, 0.6, and 1.0 GeV. Use is made of the shell-model wave function for the 15N nucleus. The contribution of single and double collisions to the Glauber operator Ω is taken into account. The sensitivity of the differential cross sections to the contributions of scattering on nucleons from different shells, to the parameters of the elementary pN amplitude, and to the energy of projectile protons is investigated. It is shown that the interference between amplitudes corresponding to different collision multiplicities, as well as between the amplitudes for scattering on nucleons from different shells, determines special features of the cross section.  相似文献   

11.
The spectra of neutrons from the (p, n) reactions on 47Ti, 48Ti, 49Ti, 53Cr, and 54Cr nuclei were measured in the proton-energy range 7–11 MeV. The measurements were performed with the aid of a fast-neutron spectrometer by the time-of-flight method over the base of the EGP-15 tandem accelerator of the Institute for Physics and Power Engineering (IPPE, Obninsk). Owing to a high resolution and a high stability of the time-of-flight spectrometer used, low-lying discrete levels could be identified reliably along with a continuum section of neutron spectra. An analysis of measured data was performed within the statistical equilibrium and preequilibrium models of nuclear reactions. The relevant calculations were performed by using the exact formalism of Hauser-Feshbach statistical theory supplemented with the generalized model of a superfluid nucleus, the back-shifted Fermi gas model, and the Gilbert-Cameron composite formula for the nuclear level density. The nuclear level densities for 47V, 48V, 49V, 53Mn, and 54Mn were determined along with their energy dependences and model parameters. The results are discussed together with available experimental data and recommendations of model systematics.  相似文献   

12.
13.
We find the vertex constant for the synthesis α + α → 8Be and the corresponding asymptotic normalization coefficient of the Gamov wave function for 8Be in the ground state. We use modern data on the position and width of the narrow resonance of this state as well as the energy dependence of the αα scattering phase shift in the s-wave known from the literature. The effective-range theory was applied with the Coulomb interaction taken into account. The parameters of the standard effective-range function expansion up to the member with k 4 (k being the relative momentum) were found.  相似文献   

14.
The low-energy structure of the dark-matter detector nuclei 71Ga, 73Ge, and 127I has been studied by using the microscopic quasiparticle-phonon model. The resulting ground states have been used to calculate theoretical predictions for detection rates of the lightest supersymmetric particle (LSP) in experiments studying elastic scattering of an LSP from an atomic nucleus. The highest rate, approximately 0.27 yr?1kg?1, among all the adopted SUSY parameters and renormalization schemes was provided by 127I at the zero limit of the detector energy threshold.  相似文献   

15.
A standard partial-wave analysis was performed on the basis of known measurements of differential cross sections for elastic p 13C scattering at energies in the range 250–750 keV. This analysis revealed that, in the energy range being considered, it is sufficient to take into account the 3 S 1 wave alone. A potential for the triplet 3 S 1-wave state of the p 13C system in the region of the J p T = 1−1 resonance at 0.55 MeV was constructed on the basis of the phase shifts obtained from the aforementioned partial-wave analysis.  相似文献   

16.
Based on an α-particle model of 12C, an optical potential for intermediate-energy proton- 12C scattering is presented in the framework of the KMT theory. The parameterized proton- 4He amplitude, the required basic input for constructing the optical potential, is obtained by fitting the proton- 4He scattering data. The differential cross-sections and analyzing powers of the proton- 12C elastic scattering at incident energies ranging from 0.2 to 1.0GeV have been calculated by using the obtained optical potential. The main features of the measured angular distributions of the cross-section and the analyzing power can be satisfactorily described. The proton- 12C total cross-sections have also been calculated, and the results are in good agreement with the experimental data at energies below 0.6GeV but underestimate the data about 6% at higher energies.  相似文献   

17.
Shell-model wave functions are used to calculate the vector analyzing power in the elastic scattering of 0.2, 0.6, and 1 GeV protons on 15C and 15N nuclei within the Glauber diffraction theory. Single and double collisions are allowed for upon the decomposition of multiple scattering. It is shown that the number of oscillations and the amplitude of the analyzing power increase with rising energy in the same angular range.  相似文献   

18.
A theory of the diffractive scattering of loosely bound three-cluster nuclei by nuclei was developed with allowance for Coulomb interaction. The differential cross sections for the scattering of projectile exotic nuclei 7Be and 8B by 12C nuclei at an energy of 40 MeV per nucleon were calculated within the proposed formalism. The results describe satisfactorily relevant experimental data.  相似文献   

19.
The cross section for 246Cm fission induced by neutrons of energy in the range 0.1 eV-20 keV was measured by the neutron lead slowing-down spectrometer (LSDS-100) of the Institute for Nuclear Research (INR, Russian Academy of Sciences, Moscow). The parameters of the resonance area and of the fission width were evaluated for several low-lying s-wave neutron resonances. The parameters of the intermediate structure in the cross section for the subbarrier fusion of 246Cm nuclei were found. The results obtained in this way were compared with available experimental data and with recommended evaluated data.  相似文献   

20.
Electron-impact excitation of odd 3 F o levels of the nickel atom has been studied experimentally. A total of 45 NiI line emission cross-sections at 50-eV exciting-electron energy were measured. Eight optical excitation functions in the 0–200 eV electron-energy range were recorded.  相似文献   

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