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1.
We investigate the dependences of the potential energy surfaces (PES) and the fusion probabilities for some cold fusion reactions leading to super-heavy elements on the nuclear shell effect and pairing energy. It is found that the shell effect plays an important role in the fusion of the super-heavy element while pairing energy's contribution is insignificant. The fusion probabilities and evaporation residue cross sections as functions of the Ge-isotope projectile bombarding ^208Pb are also investigated. It is found that evaporation residue cross sections do not always increase with the increasing neutron number of Ge-isotope.  相似文献   

2.
Role of theΛ(1600)is studied in the K^-p→Λπ^0π^0 reaction by using the effective Lagrangian approach near the threshold.We perform a calculation for the total and differential cross sections by considering the contributions from theΛ(1600)andΛ(1670)intermediate resonances decaying intoπ^0∑^*0(1385)with∑^*0(1385)decaying intoπ^0Λ.Additionally,the non-resonance process from u-channel nucleon pole is also taken into account.With our model parameters,the current experimental data on the total cross sections of the K^-p→Λπ^0π^0 reaction can be well reproduced.It is shown that we really need the contribution from the A(1600)with spin-parity J^P=1/2^+,and that these measurements can be used to determine some of the properties of theΛ(1600)resonance.Furthermore,we also plot theπ0Λinvariant mass distributions which could be tested by the future experimental measurements.  相似文献   

3.
The interaction potential for spherical-deformed reaction partners is calculated. The shape, separation and orientation dependence of the interaction potential and fusion cross section of the system ^32S+^154Sm are investigated within the double-folding model of the deformed nuclei. The effective nucleon-nucleon interaction is taken to be the M3Y-Reid potential. The density is considered for three terms of the expansion using the truncated multipole expansion method, which is a deformed Fermi shape With quadrupole and hexadecapole for the density distribution of ^154Sm. It is found for the interaction potential that the height and the position of barrier strongly depend on the deformations, the orientation angle of the deformed nucleus, and hence produce great effects on fusion cross section. The integrated fusion cross section is in good agreement with the experimental data.  相似文献   

4.
The problem of the deuteron interaction with lithium nuclei,treated as a system of two coupled pointlike clusters,is formulated to calculate the cross sections of the d+Li reaction.The d+Li reaction mechanism is described using the Faddeev theory for the three-body problem of deuteron-nucleus interaction.This theory is slightly extended for calculation of the stripping processes ^6Li(d,p)^7Li,^7Li(d,p)^8 ,^6Li(d,n)^7 Be,and ^7Li(d,n)^8 Be,as well as fragmentation reactions yielding tritium,a-particles,and continuous neutrons and protons in the initial deuteron kineticenergy region Ed=0.5-20 MeV.The phase shifts found for d+^6Li and d+^7Li elastic scattering,as part of the simple optic model with a complex central potential,were used to find the cross sections for the 6^Li(d,yM)^8 and ^7Li(d,yE1)^9 Be radiation captures.The three-body dynamics role is also summarized to demonstrate its significant influence within the d+^7Li system.  相似文献   

5.
The dynamical process in the superheavy nucleus synthesis is studied on the basis of the two-dimensional Smoluchowski equation. Special attention is paid to the isotope dependence of the cross section for the superheavy nucleus formation by means of making a comparison among the reaction systems of ^54Re+204pb, ^56Re +206Pb, and ^58Fe+^208Pb. It is found by this comparison that the formation cross section is very sensitive to the conditional saddle-point height and the neutron separation energy of the compound nucleus. Reaction systems with lower height of conditional saddle-point and smaller neutron separation energy are more favourable for the synthesis of the superheavy nucleus.  相似文献   

6.
The high-energy electronic-impact excitation cross section is directly proportional to the generalized oscillators trength (GOS) of the target atom. The generalized oscillator strengths of helium atom from the ground state to the excited states (2^1S, 2^1P and 3^1D) are calculated using the updated R-matrix codes within the first Born approximation. Our calculation results are in good agreement with the previous theoretical and experimental results at high incident energies. In order to treat the bound-bound and bound-continuum transitions in a unified manner, the GOS density is defined based on the quantum defect theory. We calculate the GOS densities of ^1S, ^1p and ^1D charmels, namely the complete high-energy collision cross sections of electronic-impact excitations into all the n^1S, n^1P and n^1D excited states. In addition to high-energy excitation cross sections, a scheme to calculate the excitation cross sections for entire incident energy range is discussed.  相似文献   

7.
The recently measured reaction cross section of ^23Al is analysed in the Glauber model with an optical limit or few-body approach.It is found that the conventional fixed core-plus-nucleon model for halo nuclei is unable to explain the observed abnormally large reaction cross section of ^23Al by any selection of the halo nucleon configurations.The reaction cross section of ^23Al can be described when the core size is enlarged,although the Coulomb barrier lagely hinders the formation of a halo sturcture for proton-rich nuclei.This is consistent with the case in s-d shell neutron-rich nuclei,where an enlarged core was proposed to explain both the reaction cross section and longitudinal momentum distribution data.  相似文献   

8.
Using the most recent differential cross section data for e-p quasi-elastic scattering, the charged pion formation and its form factor Fπ is calculated in the energy range of 2.4-4 GeV at Q^2 = 0.6-1.6 (GeV/c)^2. The functional dependence of the charged pion form factor to the separated cross section aL is investigated and compared to the previously determined result.  相似文献   

9.
A 39-target state close-coupling calculation of low-energy electron scattering from atomic oxygen is carried out with core-valence electron correlation by using R-matrix method. It is shown that the elastic cross section has a huge and sharp increase with the electron energy going down below 1eV. This remarkable structure is attributed to a few very low-lying potential resonances and the features of these resonances are given with partial cross sections. It is also shown that after considering excitations of two electrons from 2s shell, the three lowest atomic energy levels are in agreement with experimental results better than that just considering excitations of two electrons from the 2p shell as well as only one electron from the 2s shell. Elastic and two excitation (^3P→^1D and ^3P→^1S) cross sections are given and compared with the other theoretical and experimental results.  相似文献   

10.
卞宝安  张丰收 《中国物理 C》2010,34(10):1602-1608
The symmetric and asymmetric fusion reaction systems forming the same compound nuclei ^26Al, ^30Si, ^38Ar and ^170Hf are investigated with the frame of improved isospin dependent quantum molecular dynamics model. The entrance channel mass asymmetry dependence of compound nucleus formation is found by analyzing the shell correction energies, the Coulomb barriers and the fusion cross sections. The calculated fusion cross sections agree quantitatively with the experimental data. The results indicate that compound nucleus formation is favorable for the systems with larger mass asymmetry because of the smaller Coulomb contribution to the fusion barrier.  相似文献   

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