共查询到20条相似文献,搜索用时 33 毫秒
1.
Z. Ren W. Mittig B. Chen Z. Ma G. Auger 《Zeitschrift für Physik A Hadrons and Nuclei》1996,353(4):363-365
The ground state properties of proton-rich nuclei18Ne,20Mg and22Si have been investigated using the nonlinear relativistic mean-field theory with NL1 and NL-SH parameters. Proton halos in these nuclei are predicted. The characteristics of proton halos in nuclei are simply discussed. 相似文献
2.
This paper makes some qualitative and quantitative
analyses about halo formation rules of some mirror nuclei with the
relativistic mean-field (RMF) theory and the Woods--Saxon mean-field
model. By analysing two opposite effects of Coulomb interaction on
the proton halo formation, it finds that the energy level shift has
a larger contribution than that of the Coulomb barrier when the mass
number A is small, the hindrance of the Coulomb barrier becomes more
obvious with the increase of the mass number A, and the overall
effect of the Coulomb interaction almost disappears when A≈39 as
its two effects counteract with each other. 相似文献
3.
Some one-neutron halo nuclei can emit a proton in a β decay of the halo neutron. The branching ratio towards this rare decay mode is calculated within a two-body potential model of the initial core + neutron bound state and final core + proton scattering states. The decay probability per second is evaluated for the 11Be, 19C and 31Ne one-neutron halo nuclei. It is very sensitive to the neutron separation energy. 相似文献
4.
We study the proton magic O, Ca, Ni, Zr, Sn, and Pb isotope chains from the proton drip line to the neutron drip line with
the relativistic continuum Hartree-Bogoliubov (RCHB) theory. Particulary, we study in detail the properties of even-even Ca
isotopes due to the appearance of giant halos in neutron rich Ca nuclei near the neutron drip line. The RCHB theory is able
to reproduce the experimental binding energiesE
b and two neutron separation energiesS
2n very well. The predicted neutron drip line nuclei are28O,72Ca,98Ni,136Zr,176Sn, and266Pb. Halo and giant halo properties predicted in Ca isotopes withA>60 are investigated in detail through analysis of two neutron separation energies, nucleon density distributions, single
particle energy levels, and the occupation probabilities of energy levels including continuum states. The spin-orbit splitting
and the diffuseness of nuclear potential in these Ca isotopes, as well as the neighboring lighter isotopes in the drip line
Ca region and find certain possibilities of giant halo nuclei in the Ne−Na−Mg drip line nuclei are also studied. 相似文献
5.
6.
B. Nerlo-Pomorska K. Pomorski J. F. Berger J. Dechargé 《The European Physical Journal A - Hadrons and Nuclei》2000,8(1):19-29
The proton and neutron density distributions, one- and two-neutron separation energies and radii of nuclei for which neutron
halos are experimentally observed, are calculated using the self-consistent Hartree-Fock-Bogoliubov method with the effective
interaction of Gogny. Halo factors are evaluated assuming hydrogen-like antiproton wave functions. The factors agree well
with experimental data. They are close to those obtained with Skyrme forces and with the relativistic mean-field approach. 相似文献
7.
8.
9.
Yanyun Chu Zhongzhou Ren Chang Xu 《The European Physical Journal A - Hadrons and Nuclei》2008,37(3):361-366
Using a three-body model and realistic two-body potentials, we investigate the properties of the nuclei 18Ne and 28S near the proton dripline. We figure out the two-proton separation energies, occupation of the valence protons, root-mean-square
radii of matter and the valence protons. Besides, the spatial correlation densities are displayed to reflect the correlation
between the two valence protons. The first excited 0+ state of 18Ne is most likely to be a halo state according to our calculation. Turning off the Coulomb interactions among the three-body
systems, we get the two-neutron separation energies and configuration of the valence neutrons of their corresponding mirror
nuclei. The results indicate that the three-body model is proper to describe some proton-rich nuclei and can be used to deduce
reliable information. 相似文献
10.
The newly discovered neutron halos in the excited states of nuclei
12B, 13C, and
209Pb are studied by the relativistic mean-field theory.
The calculated binding energies are very close to the experimental ones. The
experimentally extracted root-mean-square radii of the last neutron with different occupations in nuclei are well reproduced by calculations. New candidates for the neutron halos in excited states are predicted and are
useful for further search of neutron halos in the excited states of stable nuclei. 相似文献
11.
《中国物理C(英文版)》2017,(11)
Very neutron-deficient nuclei are investigated with Woods-Saxon potentials,especially the newly measured A =2Z-1 nucleus ~(65)As [X.L.Tu et al.,Phys.Rev.Lett.106,112501(2011)],where the experimental proton separation energy is obtained as-90(85) keV for the first time.Careful consideration is given to quasibound protons with outgoing Coulomb wave boundary conditions.The observed proton halos in the first excited state of ~(17)F and in the ground states of ~(26,27,28)P are reproduced well,and predictions of proton halos are made for the ground states of ~(56,57)Cu and ~(65)As.The sensitivity of the results to the proton separation energy is discussed in detail,together with the effect of the l=1 centrifugal barrier on proton halos. 相似文献
12.
DANIEL R PHILLIPS 《Pramana》2014,83(5):661-671
In this paper, the recent work our group has undertaken on effective field theory (EFT) analyses of experimental data pertaining to one- and two-neutron halo nuclei is discussed. The cases of 19C and 8Li (one-neutron halos) and 22C (two-neutron halo) are considered. For 19C and 8Li electromagnetic processes, such as Coulomb dissociation and radiative capture are considered. In the 22C system the way in which the measured matter radius can be used to derive constraints on the two-neutron separation energy of this very neutron-rich system is shown. In each case the ‘Halo EFT’ ability to correlate different experimental observables with one another, in a model-independent manner, and up to an accuracy that is determined by the separation of scales in the halo system is shown. 相似文献
13.
D.Q. Fang W.Q. Shen J. Feng X.Z. Cai H.Y. Zhang Y.G. Ma C. Zhong Z.Y. Zhu W.Z. Jiang W.L. Zhan Z.Y. Guo G.Q. Xiao J.S. Wang J.Q. Wang J.X. Li M. Wang J.F. Wang Z.J. Ning Q.J. Wang Z.Q. Chen 《The European Physical Journal A - Hadrons and Nuclei》2001,12(3):335-339
Measurements of reaction cross-sections ( σR's) for some proton-rich nuclei ( N = 11–15 isotones) on carbon target at intermediate energies have been performed on RIBLL of HIRFL. A larger enhancement of
the σR for 27P has been observed than for its neighboring nuclei. A large difference between the proton and neutron density distributions
(proton halo) is necessary to explain the enhanced cross-section for 27P within the framework of the Glauber model. Density distributions with HO-type core plus Yukawa-square tail and rms radii
for 27P have been deduced from the measured σR data for the first time, which conform the long tail in its densities as predicted by RMF calculations.
Received: 23 May 2001 / Accepted: 7 November 2001 相似文献
14.
The current study on proton halos in exotic light nuclei is reviewed and discussed. We place emphasis on the newly discovered proton halo in 23Al. A measurement of the reaction cross section of N=10 isotones and Z=13 isotopes is performed at Lanzhou in China. An abnormal increase in the reaction cross section is observed for 23Al. This abnormal increase, combined with other data, strongly suggests that there is a proton halo in 23Al. The possible cause for a proton halo in 23Al is analyzed, and it is found that deformation can be important for it. Other candidates for proton halos are predicted. 相似文献
15.
The low-lying electric dipole strengths in proton-rich nuclei 17F and 17Ne, which can be produced at HIRFL-CSR in Lanzhou, are investigated. In the framework of the covariant density functional theory the self-consistent relativistic Hartree Bogoliubov model and the relativistic quasiparticle random phase approximation with the NL3 parameter set and Gogny pairing interaction are adopted in the calculations. A pronounced dipole peak appears below 10 MeV in 17Ne, but does not occur in 17F. The properties of this low-lying E1 excitation in 17Ne are studied, which may correspond to a proton pygmy resonance with different characteristics from those of giant dipole resonance. 相似文献
16.
SUN BaoHua ZHAO PengWei & MENG Jie School of Physics Nuclear Energy Engineering Beihang University Beijing China Ⅱ.Physikalisches Institut Justus-Liebig-Universitt Gieβen Germany State Key Laboratory for Nuclear Physics Technology School of Physics Peking University Beijing 《中国科学:物理学 力学 天文学(英文版)》2011,(2)
The masses,one-and two-proton separation energies of proton-rich nuclei with Z = 20-55,are computed using the measured masses of mirror neutron-rich nuclei and the Coulomb displacement energies calculated from the relativistic point-coupling model.The implications for the proton drip lines,candidates for two-proton emitters,as well as the impact on the astrophysical rp-process are discussed. 相似文献
17.
《Nuclear Physics A》1998,628(2):221-254
We have made a detailed study of the ground-state properties of nuclei in the light-mass region with atomic numbers Z = 10–22 in the framework of the relativistic mean-field (RMF) theory. The nonlinear σω model with scalar self-interaction has been employed. The RMF calculations have been performed in an axially deformed configuration using the force NL-SH. We have considered nuclei about the stability line as well as those close to proton and neutron drip lines. It is shown that the RMF results provide good agreement with the available empirical data. The RMF predictions also show reasonably good agreement with those of the mass models. It is observed that nuclei in this mass region are found to possess strong deformations and exhibit shape changes all along the isotopic chains. The phenomenon of shape coexistence is found to persist near the stability line as well as near the drip lines. It is shown that the magic number N = 28 is quenched strongly, thus enabling the corresponding nuclei to assume strong deformations. Nuclei near the neutron and proton drip lines in this region are also shown to be strongly deformed. 相似文献
18.
《Nuclear Physics A》1999,650(2):176-196
The relativistic continuum Hartree-Bogoliubov (RCHB) theory, which is the extension of the relativistic mean field and the Bogoliubov transformation in the coordinate representation, has been used to study tin isotopes. The pairing correlation is taken into account by a density-dependent force of zero range. The RCHB theory is used to describe the even-even tin isotopes all the way from the proton drip line to the neutron drip line. The contribution of the continuum which is important for nuclei near the drip-line has been taken into account. The theoretical S2n as well as the neutron, proton, and matter rms radii are presented and compared with the experimental values where they exist. The change of the potential surface with the neutron number has been investigated. The diffuseness of the potentials in tin isotopes is analyzed through the spin-orbital splitting in order to provide new way to understand the halo phenomena in exotic nuclei. The systematic of the isospin and energy dependence of these results are extracted and analyzed. 相似文献
19.
H.F. Lü J. Meng S.Q. Zhang S.-G. Zhou 《The European Physical Journal A - Hadrons and Nuclei》2003,17(1):19-24
Properties of single- Λ and double- Λ hypernuclei for even-N Ca isotopes ranging from the proton dripline to the neutron dripline are studied using the relativistic continuum Hartree-Bogoliubov
theory with a zero-range pairing interaction. Compared with ordinary nuclei, the addition of one or two Λ-hyperons lowers
the Fermi level. The predicted neutron dripline nuclei are, respectively, 75
ΛCa and 76
2ΛCa, as the additional attractive force provided by the Λ-N interaction shifts nuclei from outside to inside the dripline.
Therefore, the last bound hypernuclei have two more neutrons than the corresponding ordinary nuclei. Based on the analysis
of two-neutron separation energies, neutron single-particle energy levels, the contribution of continuum and nucleon density
distribution, giant halo phenomena due to the pairing correlation, and the contribution from the continuum are suggested to
exist in Ca hypernuclei similar to those that appear in ordinary Ca isotopes.
Received: 21 October 2002 / Accepted: 11 January 2003 / Published online: 8 April 2003 相似文献
20.
One-proton, two-proton, and α-particle transfer have been studied on nuclei with closed neutron shell N = 82 using 16O beams of 63 to 66.5 MeV incident energy. Transfer probabilities defined in a semiclassical model are derived for the different reaction channels. For this purpose the Q-value and angular dependence of the cross section are discussed. The two-proton transfer to the ground states shows an enhancement by a factor 20–25 compared to other nuclei, showing the effect of the proton pairing in these nuclei (they correspond to equivalent neutron configurations in 108, 110, 112Sn). The total transfer probability follows a common trend for all three target nuclei as a function of energy above the Coulomb barrier for the proton and two-proton transfer, respectively, but not for the four-nucleon transfer. 相似文献