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1.
The momentum distributions in nuclei like4He,16O and40Ca are explicitly calculated within a phenomenological model which includes dynamical short range and tensor correlation effects. The common behaviour of such distributions in the high momentum region, already established in light nuclei, is extended to the medium weight region. Comparison with existing calculations is discussed and, for completeness, also form factors are evaluated within the same framework.  相似文献   

2.
A K HAMOUDI  M A HASAN  A R RIDHA 《Pramana》2012,78(5):737-748
The nucleon momentum distributions (NMD) and elastic electron scattering form factors of the ground state for 1p-shell nuclei with Z?=?N (such as 6Li, 10B, 12C and 14N nuclei) have been calculated in the framework of the coherent density fluctuation model (CDFM) and expressed in terms of the weight function $\left| {f( x )} \right|^2$ . The weight function has been expressed in terms of nucleon density distribution (NDD) of the nuclei and determined from the theory and the experiment. The feature of the long-tail behaviour at high-momentum region of the NMDs has been obtained by both the theoretical and experimental weight functions. The experimental form factors F(q) of all the considered nuclei are very well reproduced by the present calculations for all values of momentum transfer q. It is found that the contributions of the quadrupole form factors F C2(q) in 10B and 14N nuclei, which are described by the undeformed p-shell model, are essential for obtaining a remarkable agreement between the theoretical and experimental form factors.  相似文献   

3.
We evaluate the effect of a large depletion of the Fermi sea on the charge largeness of this depletion makes it impossible to construct an independent particle model which would simultaneously reproduce both the diagonal and the off-diagonal elements of the nuclear one-body density matrix.  相似文献   

4.
Single-particle occupation probabilities and the depletion of the nuclear Ferrmi sea (caused by the short-range nucleon-nucleon correlations) as well as momentum distributions in closeds-d shell nuclei are calculated within the Jastrow correlation method in its low-order approximation. The theoretical results for the occupation probabilities are discussed in relation to experimental data from (e, e′ p) reactions and to other theoretical estimates.  相似文献   

5.
Differential cross sections and longitudinal momentum distributions of observed particles are calculated for stripping reactions that result from diffractive interaction between halo nuclei and targets. The applicability of different analytic methods of calculation is considered. The advantages of an improved approximation of small target radius are demonstrated for valent halo nucleon absorption radii of 2–4 fm in describing momentum distributions in particular.  相似文献   

6.
The possibility of obtaining information on nucleon momentum distributions in few-body systems by a coherent analysis of exclusive and inclusive electron scattering is discussed using the concept ofy-scaling.Presented at the symposium Mesons and Light Nuclei, Bechyn, Czechoslovakia, May 27–June 1, 1985.  相似文献   

7.
《Physics letters. [Part B]》1986,172(2):135-138
The nuclear phase-space distribution is calculated in a semi-classical approximation using the inverse Laplace transformation of the Bloch density. For a local Woods-Saxon potential, both the phase-space and the momentum distributions are shown as functions of the temperature.  相似文献   

8.
9.
The nucleon pairing effect that is analyzed in the present paper is one of the striking manifestations of nuclear dynamics. Nucleon pairing for different chains of nuclei dependent upon the number of protons or neutrons in the nucleus allows one to explain the emergence of a great number of positive-parity states, which form a ground state multiplet, in even-even nuclei in the excitation energy range E* < 4 MeV. The interaction of paired nucleons with vibrational and rotational degrees of freedom of a nucleus produces a wide variety of excitation spectra of positive-parity states in even-even nuclei.  相似文献   

10.
The use of elastic proton scattering at intermediate and high energies to obtain information about the density distributions of unstable nuclei is investigated. A comparison between the relativistic impulse approximation (RIA) and Glauber model for proton scattering from 16O, 40Ca, 44Ca and 48Ca at medium energies is performed. We used density distributions derived from the relativistic mean-field theory, employing the recent relativistic force NL-RA1, as well as experimental and phenomenological densities. It is found that the eikonal approximation can describe the cross-section only at small scattering angles and is weakly sensitive to the density distributions, while the RIA nicely produced the experimental cross-sections, even at medium and larger angles, and was very sensitive to the nuclear densities. Furthermore, the RIA better describes the isospin dependence of the cross-section. We used the RIA to investigate the density distribution of 58Ca for proton scattering at different energies. It is found that the cross-section strongly depends on the parameters of the density distribution even at a small scattering angle. These results are important in extracting information about the structure of unstable nuclei. We also investigated the RIA and its sensitivity in describing halo nuclei such as 6He. We used for 6He a no-halo Gaussian density and a realistic-halo density that derived in the cluster orbital shell model approximation and contains the extended distribution of the valence nucleons. Comparison with the recent experimental data at GSI at 717 MeV/nucleon shows that the RIA successfully described the data at all considered range of the momentum transfer and on the other hand favor the halo structure of 6He. Received: 1 December 2001 / Accepted: 31 July 2002 / Published online: 11 February 2003 RID="a" ID="a"e-mail: mrashdan@hotmail.com Communicated by P. Schuck  相似文献   

11.
A finite temperature Thomas-Fermi method has been used to study the nucleon transfer between two hot slabs of symmetric nuclear matter. Special attention has been paid to temperature effects neglected in earlier calculations. As a result, closed and ready-to-use formulas for the exchange and transfer nucleon flux at zero relative momentum are given as a function of the temperature.  相似文献   

12.
The process of nuclear excitation above threshold for nucleon decay in high energy electron scattering is considered. On the basis of the particle-hole shell model a formalism is proposed which allows one to describe electroexcitation of nuclei in a unified manner both in the resonance and quasielastic scattering regions. Numerical calculations were made for the 12C nucleus taking into account the mixing of proton and neutron configurations (channels) of the particle-hole type in the continuum.  相似文献   

13.
Manifestations of the neutron halo in extremely neutron-rich nuclei are investigated by the Hartree-Fock method using the Skyrme forces (SkM*, Ska, Sly4, SkI2) with allowance for axial deformation. The investigated nuclei, which lie beyond the theoretical neutron drip line (NDL), form peninsulas of nuclei stable with respect to one-neutron emission and belong to chains of isotones with the neutron number N = 32, 58, 82, 126, 184, and 258.  相似文献   

14.
《Nuclear Physics A》1999,650(1):47-61
The halo nuclei 11Be and 11Li have been studied in core-breakup reactions where the halo neutrons are expected to be released without a major distortion due to the reaction. The widths of the halo-neutron momentum distributions have been extracted in coincidence with He fragments, Γ = 32 ± 4 MeV/c, and Li fragments, Γ = 42 ± 4 MeV/c for 11Be and with He fragments, Γ = 42 ± 6 MeV/c for 11Li. The 11Be breakup gives a very low neutron multiplicity of 0.38±0.09 which is a manifestation of the shadowing of the neutron in the core-breakup reaction. This value can be understood from a simple theoretical calculation, which also accounts for the observed transverse momentum widths at small angles.  相似文献   

15.
The recent development of the technique of inelastic x-ray scattering to study the electron momentum distribution in the scatterer is surveyed. The simple relationship between the electron momenta and the Compton line shape in the impulse approximation is derived, and the validity of that approximation is discussed in the light of recent measurements. Current areas of research are reviewed.  相似文献   

16.
Basic properties of the ground states of spherical nuclei are investigated in a nonlocal extended Thomas-Fermi approximation under the assumption of Skyrme forces. It is shown that, for nuclei occurring near the β-stability line, the binding energies, the root-mean-square radii, and the density distributions found on this basis agree well with experimental data. Binding energies, root-mean-square radii, and density distributions are also calculated for the ground states of nuclei lying far off the β-stability line and for superheavy elements. For the proton, the neutron, and the total particle density, the thickness of the diffuse layer is investigated as a function of the number of neutrons in tin isotopes.  相似文献   

17.
Within the three-body α2N and 2αN models of the 6Li and 9Be nuclei, respectively, the spectroscopic factors and the momentum distributions of nucleons are computed for the cases where residual nuclei can be formed both in the ground and in excited states. The impact of model parameters on the values of one-nucleon features is discussed. The results of the calculations performed in the present study are compared with available experimental data.  相似文献   

18.
A null 4-vector °, based on Dirac's relativistic electron equation, is shown explicitly for a plane wave and various Coulomb states. This 4-vector constitutes a mechanical model for the electron in those states, and expresses the important spinor quantities represented conventionally byn, f, g, m, j, ,1, ands. The model for a plane wave agrees precisely with the relation between velocity and phase gradient customarily used in quantum theory, but the models for Coulomb states contradict that relation.  相似文献   

19.
The isobaric yield ratio difference (IBD) between two reactions of similar experimental setups is found to be sensitive to nuclear density differences between projectiles. In this article, the IBD probe is used to study the density variation in neutron-rich 48Ca . By adjusting diffuseness in the neutron density distribution, three different neutron density distributions of 48Ca are obtained. The yields of fragments in the 80A MeV 40, 48Ca + 12C reactions are calculated by using a modified statistical abrasion-ablation model. It is found that the IBD results obtained from the prefragments are sensitive to the density distribution of the projectile, while the IBD results from the final fragments are less sensitive to the density distribution of the projectile.  相似文献   

20.
Elastic electron-deuteron scattering at high momentum transfer is investigated within the Bethe-Salpeter approach. The relativistic covariant Graz II separable kernel of nucleon-nucleon interactions is used to analyze the deuteron structure functions, form factors, and tensor of polarization components. The modern data for the electromagnetic structure of nucleons from the double polarization experiments, as well as some other models of the nucleon form factors, are considered.  相似文献   

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