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1.
The interplay of diffraction dissociation and nuclear shakeoff is considered in a schematic but still realistic model for
the case of the break-up of halo nuclei on light targets. We demonstrate that the shakeoff effect, arising from the momentum
imparted by the core diffraction, is small but still identifiable in the experimental data for the dissociation of the one-
and two-neutron halo nuclei 11Be and 11Li.
Received: 29 October 1999 / Revised version: 15 January 2000 相似文献
2.
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R. Chatterjee L. Fortunato A. Vitturi 《The European Physical Journal A - Hadrons and Nuclei》2008,35(2):213-220
We investigate the role of higher multipole excitations in the electromagnetic dissociation of one-neutron halo nuclei within
two different theoretical models --a finite-range distorted-wave Born approximation and another in a more analytical method
with a finite-range potential. We also show, within a simple picture, how the presence of a weakly bound state affects the
breakup cross-section. 相似文献
4.
Two causes of nonlocality inherent in nucleon-nucleus scattering are considered. They are the results of two-nucleon antisymmetry
of the projectile with each nucleon in the nucleus and the dynamic polarization potential representation of channel coupling.
For energies ∼ 40 -300MeV, a g -folding model of the optical potential is used to show the influence of the knock-out process that is a result of the two-nucleon
antisymmetry. To explore the dynamic polarization potential caused by channel coupling, a multichannel algebraic scattering
model has been used for low-energy scattering. 相似文献
5.
The DWBA method is tested through a comparison with a microscopic cluster model on the 13C (, n) 16O reaction in the energy range E = 0-5MeV, relevant for nuclear astrophysics. The conditions of the calculation are as close as possible to the reference model, i.e. the nucleus-nucleus potentials are phase equivalent, and the spectroscopic factors are identical. We find significant differences between both approaches, which means that antisymmetrization effects, missing in the DWBA, are important. Our work also points out the strong sensitivity of the DWBA with input parameters. 相似文献
6.
R. Arora R. K. Puri R. K. Gupta 《The European Physical Journal A - Hadrons and Nuclei》2000,8(1):103-114
We analyse the fusion cross-sections, calculated by using two different analytical parameterisations and compare them with
the experimental data. Both the parameterisations are based on ion-ion potentials calculated within the framework of Skyrme
energy density formalism. In the first case, the ion-ion potential (including the spin-density term) was parameterised and
then, by adding the Coulomb potential, one could compute the fusion barrier analytically. In the second case, the calculated
fusion barrier heights and positions were parameterised directly. Both of these (previously) reported parameterisations are
used here to calculate the fusion barriers and fusion excitation functions for more than 50 reactions belonging to the s-d and f-shell nuclei. A detailed comparison of these parametrisations with the experimental and several other theoretical results
shows that both of these parameterisations are able to reproduce the experimental data equally well. As the (second) direct
parameterisation depends only on the charges and masses of colliding nuclei, it is very useful for predicting/ understanding
the fusion process in low energy heavy-ion reactions.
Received: 24 February 1999 / Accepted: 16 March 2000 相似文献
7.
R. Lewis 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):409-414
Inclusive electron scattering cross-sections in the quasielastic and resonance regions for few GeV electrons are well represented
in terms of scaling functions and scaling variables, the so-called superscaling analysis (SuSA). The concepts of scaling of
the first and second kinds and superscaling are discussed, as are several mechanisms which are known to yield scaling violations.
Given the high quality of scaling for cross-sections at appropriate kinematics, it is shown how the ideas can be turned around
to provide predictions for both charge-changing and neutral current neutrino reactions with nuclei at comparable kinematics. 相似文献
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9.
D. Shapira 《The European physical journal. Special topics》2007,150(1):55-60
The availability of accelerated fission fragments at HRIBF allows us to
study fusion reactions where one of the reactants is a short-lived
exotic nucleus. Most interesting in this respect are entrance channels
involving neutron-rich target and projectile – where enhanced survival
probability of the compound system may allow the synthesis of heavier
system. Much depends though on the dynamic evolution of the captured
nuclei into a compound nucleus and the ensuing competition between
fission
and evaporation residue decay modes. Our studies of fusion between heavy
neutron-rich nuclei are aimed at acquiring data that will lead to the
understanding and eventually the ability to predict the probabilities
for these different processes. 相似文献
10.
A modified Woods-Saxon (MWS) potential is proposed for describing nucleus-nucleus interaction based on the Skyrme energy-density functional approach. Fusion barriers for a large number of fusion reactions from light to heavy systems can be described well with this potential. The suitable incident energies for fusion reactions leading to superheavy nuclei are also explored. It seems to us that the MWS potential is useful for selecting the suitable incident energies for fusion reactions for producing super-heavy nuclei. 相似文献
11.
Nuclear Potential and Fusion Cross Sections for Synthesizing Super-Heavy Elements in Di-nuclear Systems
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A double foMing method with simplified Skyrme-type nucleon nucleon interaction is used to calculate the nuclear interaction potential between two nuclei. The calculation is performed in tip-to-tip orientation of the two nuclei if they are deformed. Based on this method, the potential energy surfaces~ the fusion probabilities and the evaporation residue cross sections for some cold fusion reactions leading to super-heavy elements within di-nuclear system model are evaluated. It is indicated that after the improvement, the exponential decreasing systematics of the fusion probability with increasing charge number of projectile on the Pb based target become better and the evaporation residue cross sections are in better agreement with the experimental data. 相似文献
12.
I. Peter W. von Oertzen S. Thummerer H.G. Bohlen B. Gebauer J. Gerl M. Kaspar I. Kozhoukharov T. Kröll M. Rejmund H.J. Wollersheim I.J. Thompson 《The European Physical Journal A - Hadrons and Nuclei》2003,16(4):509-525
At energies below the Coulomb barrier, neutron transfer and Coulomb excitation have been measured in a very heavy asymmetric
nuclear system, in 206Pb + 118Sn. These are semi-magic nuclei showing super-fluid properties. Particle-γ coincidence techniques using 5 Euroball Cluster
detectors (EB), combined in a set-up with the Heidelberg-Darmstadt NaI Crystal Ball (CB), have been used. Position-sensitive
detectors allowed the observation of scattering processes covering angles from 110 up to 150 degrees. The fragments are identified
via the known γ-decays of the lowest excited states using the high resolution of EB. Using the unique feature of the set-up
with the CB, transfer to well-defined final channels with known quantum numbers is selected using the high-efficiency multiplicity
filter of the CB with no second γ-ray, i.e. without feeding. The data are analysed using the semi-classical approach and transfer probabilities are obtained. Coulomb
excitation has been analysed using known transition probabilities. The enhancement is deduced for the two-neutron transfer
populating the low-lying super-fluid 2+ states in 120Sn and 116Sn, while the 2n transition remains in the ground state for the 20NPb nuclei. Large enhancements up to EF ≃ 103 are observed. This is the first observation of neutron pair transfer enhancement for a heavy nuclear binary system with super-fluid
properties with experimentally separated levels. The calculations with microscopic 2-neutron wave functions, with configuration
mixing over six shell model configurations and using the coupled reaction channels approach, reproduce well the observed probabilities
and the enhancement.
Received: 27 August 2002 / Accepted: 9 December 2002 / Published online: 25 March 2003
RID="a"
ID="a"e-mail: oertzen@hmi.de
Communicated by D. Schwalm 相似文献
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V. K. Lukyanov 《Physics of Atomic Nuclei》2006,69(6):1033-1044
Nucleus-nucleus scattering is considered in the high-energy approximation and on the basis of Glauber-Sitenko microscopic theory in the optical limit. Analytic expressions for eikonal phase shifts are given for the case of Fermi-type realistic potentials and nuclear-density distributions. The effect of taking into account the distortions of the trajectories of the nuclei involved and the nuclear-density dependence of nucleon-nucleon forces on the total reactions cross sections is illustrated. The sensitivity of the reaction cross sections to the choice of model for the 6He projectile nucleus, which involves a neutron halo, is explored. Semimicroscopic optical potentials are introduced in order to describe differential cross sections for elastic scattering. The results of the present calculations are compared with available experimental data. 相似文献
15.
K. V. Lukyanov V. K. Lukyanov E. V. Zemlyanaya A. N. Antonov M. K. Gaidarov 《The European Physical Journal A - Hadrons and Nuclei》2007,33(4):389-400
Calculations of microscopic optical potentials (OPs) (their real and imaginary parts) are performed to analyze the 6
He + p elastic-scattering data at a few tens of MeV/nucleon (MeV/N). The OPs and the cross-sections are calculated using three model
densities of 6He . Effects of the regularization of the NN forces and their dependence on nuclear density are investigated. Also, the role
of the spin-orbit terms and of the non-linearity in the calculations of the OPs, as well as effects of their renormalization
are studied. The sensitivity of the cross-sections to the nuclear densities was tested and one of them that gives a better
agreement with the data was chosen. 相似文献
16.
We have calculated the fission probabilities for 237Np, 233, 235, 238U, 232Th, and natPb following the absorption of photons with energies from 68 MeV to 3.77 GeV using the RELDIS Monte Carlo code. This code implements the cascade-evaporation-fission model of intermediate-energy photonuclear reactions. It includes multiparticle production in photoreactions on intranuclear nucleons, pre-equilibrium emission, and the statistical decay of excited residual nuclei via competition of evaporation, fission, and multifragmentation processes. The calculations show that in the GeV energy region the fission process is not solely responsible for the entire total photoabsorption cross-section, even for the actinides. The fission probabilities are 80-95% for 233U, 235U, and 237Np, 70-80% for 238U, and only 55-70% for 232Th. This is because certain residual nuclei that are created by deep photospallation at GeV photon energies have relatively low fission probabilities. The results of those model calculations are in reasonable agreement (at the 10% level) with recent experimental data on relative photofission cross-sections for 237Np and 233, 235, 238U (but not for 232Th or natPb) from the Saskatchewan and Jefferson Laboratories over a very wide range in photon energy. Using our calculated fission probabilities plus the total photoabsorption cross-sections per nucleon, estimated from previous cross-section data for nuclei from C to Pb, we can infer absolute photofission cross-sections for the actinide nuclei and compare them with the SAL and JLab results. The resulting discrepancies, however, clearly demonstrate the need for direct measurement of the total photoabsorption cross-sections for the heavy actinides. 相似文献
17.
R.P. Duperray K.V. Protasov A.Yu. Voronin 《The European Physical Journal A - Hadrons and Nuclei》2003,16(1):27-34
The experimental data of the antideuteron production in proton-proton and proton-nucleus collisions are analyzed within a
simple model based on the diagrammatic approach to the coalescence model. This model is shown to be able to reproduce most
of the existing data without any additional parameter.
Received: 18 April 2002 / Accepted: 30 August 2002 / Published online: 17 January 2003
RID="a"
ID="a"e-mail: duperray@isn.in2p3.fr
RID="b"
ID="b"e-mail: protasov@isn.in2p3.fr
RID="c"
ID="c"e-mail: avoronin@aha.ru
Communicated by A. Molinari 相似文献
18.
G. G. Adamian N. V. Antonenko W. Scheid 《The European Physical Journal A - Hadrons and Nuclei》2009,41(2):235-241
Within the dinuclear system model we analyse the production of unknown superheavy nuclei in various actinide-based complete-fusion
reactions. Different predictions of the properties of the heaviest nuclei are used. The dependence of the calculated evaporation
residue cross-sections on the predicted shell structure and magic numbers of the heaviest nuclei is discussed. 相似文献
19.
Recent data on the electroproduction of hadrons on nuclei are discussed. The effects of the nuclear absorption are investigated
using the Lund model for the electroproduction on nucleons. A simple geometrical model with a minimal number of assumptions
and free parameters is shown to describe the data reasonably well. 相似文献
20.
W. M. Seif 《The European Physical Journal A - Hadrons and Nuclei》2008,38(1):85-95
To probe the nuclear equation of state, several fusion cross-sections have been analyzed using microscopic nucleus-nucleus
potentials calculated in the framework of the Hamiltonian energy density approach through the well-known Skyrme nucleon-nucleon
effective interaction with eighteen different parameterizations which express various equations of state. Three density-dependent
M3Y-Paris effective forces are examined also within the double-folding model. The various effective forces give incompressibility
modulus values which vary over a rather wide range between 188MeV and 372MeV. The extracted fusion barrier distributions are
examined too with the same aim. The most successfully investigated interactions in deriving satisfactory fusion excitation
functions as well as barrier distributions are those giving equations of state with nuclear incompressibility values in the
range of 230-241MeV, according to the isospin asymmetry of the interacting nuclei. 相似文献