Very neutron-deficient nuclei are investigated with Woods-Saxon potentials,especially the newly measured A =2Z-1 nucleus 65As [X.L.Tu et al.,Phys.Rev.Lett.106,112501（2011）],where the experimental proton separation e...Very neutron-deficient nuclei are investigated with Woods-Saxon potentials,especially the newly measured A =2Z-1 nucleus 65As [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 17F and in the ground states of 26,27,28P are reproduced well,and predictions of proton halos are made for the ground states of 56,57Cu and 65As.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.展开更多
Elastic electron scattering on the exotic light nucleus 28S is investigated in the plane wave Born approximation. The variation of the squared form factors of 28S with momentum transfer is compared with that of 32S. I...Elastic electron scattering on the exotic light nucleus 28S is investigated in the plane wave Born approximation. The variation of the squared form factors of 28S with momentum transfer is compared with that of 32S. It is found that the behavior of the form factors near the second minimum (with a moderate momentum transfer) is sensitive to the alteration of the charge density distribution of halo protons in 28S. This indicates that elastic electron scattering can be a good probe of the structure of proton-halo nuclei.展开更多
Inthe framework of the single-particle potential model, the root-meamsquare radii of s-wave valence proton distributions for P and S isotopes have been systematically calculated. The scaling law of s-wave valence prot...Inthe framework of the single-particle potential model, the root-meamsquare radii of s-wave valence proton distributions for P and S isotopes have been systematically calculated. The scaling law of s-wave valence proton distributions is obtained by analyzing the relation between radii and separation energies. Necessary condition for the occurrence of 2sl/2-state proton halos is deduced from the scaling law. Quantitative condition derived from this work can to some extent serve as reference for proton halo search.展开更多
In the present research, we used the 17^Ne beam at 30.8 MeV/u to bombard the 43 mg/cm^2 12^C target and measured the angular correlations between the fragments and emitted proton. In the break-up reaction of 17^Ne, on...In the present research, we used the 17^Ne beam at 30.8 MeV/u to bombard the 43 mg/cm^2 12^C target and measured the angular correlations between the fragments and emitted proton. In the break-up reaction of 17^Ne, one-proton knockout would result in an unstable nu- cleus 16^F, which would further decay by the proton emission. The measured angular correlation between the 16^F momentum and the relative momentum of its decay products was compared with theoretical calculations and indicated that the valence proton in 17^Ne has the most probability to be situated in the s1/2 orbital with a small admixture of the d5/2 orbital. The present results suggest that 17^Ne has a halo structure.展开更多
Proton-halo breakup behavior in theε0→0 limit(whereε0 is the ground-state binding energy)is stud-ied around the Coulomb barrier in the^(8)B+^(58)Ni reaction for the first time.For practical purposes,apart from the ...Proton-halo breakup behavior in theε0→0 limit(whereε0 is the ground-state binding energy)is stud-ied around the Coulomb barrier in the^(8)B+^(58)Ni reaction for the first time.For practical purposes,apart from the ex-perimental 8B binding energy of 137 keV,three more arbitrarily chosen values(1,0.1,0.01 keV)are considered.It is first shown that the Coulomb barrier between the core and the proton prevents the^(7)Be+p system from reaching the state of an open proton-halo system,w hich,among other factors,would require the ground-state wave function to extend to infinity in the asymptotic region,asε0→0.The elastic scattering cross section,which depends on the density of the ground-state wave function,is found to have a negligible dependence on the binding energy in this limit.The total,Coulomb and nuclear breakup cross sections are all reported to increase significantly fromε0=137 to 1.0 keV,and converge to their maximum values asε0→0.This increase is mainly understood as coming from a longer tail of the ground-state wave function forε0≤1.0 keV,compared to that forε0=137 keV.It is also found that the effect of the continuum-continuum couplings is to slightly delay the convergence of the breakup cross section.The analysis of the reaction cross section indicates a convergence of all the breakup observables asε0→0.These results provide a better sense of the dependence of the breakup process on the breakup threshold.展开更多
Elastic proton scattering from Be, C, and O isotopes has been investigated in the relativistic impulse approximation （RIA）. In the calculations, the nucleon-nucleus optical potentials are obtained using ground state...Elastic proton scattering from Be, C, and O isotopes has been investigated in the relativistic impulse approximation （RIA）. In the calculations, the nucleon-nucleus optical potentials are obtained using ground state nuclear matter densities, which are computed using the relativistic mean field model with the FSU parameter set. The scattering observables, including differential cross section, analyzing power, and spin-rotation function, are analyzed. It is found that the scattering observables for O isotopic chains display a clear mass dependence, for instance, the minimum analyzing power shifts to a low scattering angle with increasing mass number. While for the Be isotopic chain, the emergence of a neutron halo in ^（14） Be breaks this trend, i.e., the minimum analyzing powers for ^（12） Be and ^（14） Be are almost the same as each other.展开更多
The Halo and cluster structure at the ground state of unstable nuclei are among the most exciting phenomena of current nuclear physics. Probing these structures requires a careful selection of reaction tools. In the p...The Halo and cluster structure at the ground state of unstable nuclei are among the most exciting phenomena of current nuclear physics. Probing these structures requires a careful selection of reaction tools. In the past twenty years, knockout reactions have been used intensively to investigate spectroscopically the structure of unstable nuclei. In this report we have illustrated the latest development of the knockout reaction tool and have emphasized the recoiled proton tagging method. A quantitative criteria is developed to evaluate the quasi-free feature of the knockout process. The newly discovered ＂towing mode＂ reaction tool is also outlined and its applicability at transit energies is discussed.展开更多
Space-charge forces acting in mismatched beams have been identified as a major cause of beam halo. In this paper,we describe the beam halo experimental results in a FODO beam line at IHEP. With this beam transport lin...Space-charge forces acting in mismatched beams have been identified as a major cause of beam halo. In this paper,we describe the beam halo experimental results in a FODO beam line at IHEP. With this beam transport line, experiments are carried out to compare the measured data with the multi-particle simulations and to study the formation of a beam halo. The maximum measured amplitudes of the matched and mismatched beam profiles agree well with simulations. Details of the experiment are presented.展开更多
基金Supported by Science and Technology Development Fund of Macao(007/2016/A1,039/2013/A2)National Natural Science Foundation of China(11535004,11035001,11375086,11105079,10735010,10975072,11175085,11235001)+1 种基金National Major State Basic Research and Development of China(2016YFE0129300)Research Fund of Doctoral Point(RFDP)(20100091110028)
文摘Very neutron-deficient nuclei are investigated with Woods-Saxon potentials,especially the newly measured A =2Z-1 nucleus 65As [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 17F and in the ground states of 26,27,28P are reproduced well,and predictions of proton halos are made for the ground states of 56,57Cu and 65As.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.
基金supported by the National Natural Science Foundation of China(Grant No.10125521)by the 973 National Major State Basic Research and Development of China(Grant No.G2000077400)by the Research Fund for the Doctoral Program of Higher Education under contract No.20010284036.
文摘Elastic electron scattering on the exotic light nucleus 28S is investigated in the plane wave Born approximation. The variation of the squared form factors of 28S with momentum transfer is compared with that of 32S. It is found that the behavior of the form factors near the second minimum (with a moderate momentum transfer) is sensitive to the alteration of the charge density distribution of halo protons in 28S. This indicates that elastic electron scattering can be a good probe of the structure of proton-halo nuclei.
基金supported by National Natural Science Foundation of China (No.10947106)
文摘Inthe framework of the single-particle potential model, the root-meamsquare radii of s-wave valence proton distributions for P and S isotopes have been systematically calculated. The scaling law of s-wave valence proton distributions is obtained by analyzing the relation between radii and separation energies. Necessary condition for the occurrence of 2sl/2-state proton halos is deduced from the scaling law. Quantitative condition derived from this work can to some extent serve as reference for proton halo search.
基金supported by National Natural Science Foundation of China (Nos.10775005,10735010,J0730316)Chinese Major State Basic Research Development Program (2007CB815002)
文摘In the present research, we used the 17^Ne beam at 30.8 MeV/u to bombard the 43 mg/cm^2 12^C target and measured the angular correlations between the fragments and emitted proton. In the break-up reaction of 17^Ne, one-proton knockout would result in an unstable nu- cleus 16^F, which would further decay by the proton emission. The measured angular correlation between the 16^F momentum and the relative momentum of its decay products was compared with theoretical calculations and indicated that the valence proton in 17^Ne has the most probability to be situated in the s1/2 orbital with a small admixture of the d5/2 orbital. The present results suggest that 17^Ne has a halo structure.
文摘Proton-halo breakup behavior in theε0→0 limit(whereε0 is the ground-state binding energy)is stud-ied around the Coulomb barrier in the^(8)B+^(58)Ni reaction for the first time.For practical purposes,apart from the ex-perimental 8B binding energy of 137 keV,three more arbitrarily chosen values(1,0.1,0.01 keV)are considered.It is first shown that the Coulomb barrier between the core and the proton prevents the^(7)Be+p system from reaching the state of an open proton-halo system,w hich,among other factors,would require the ground-state wave function to extend to infinity in the asymptotic region,asε0→0.The elastic scattering cross section,which depends on the density of the ground-state wave function,is found to have a negligible dependence on the binding energy in this limit.The total,Coulomb and nuclear breakup cross sections are all reported to increase significantly fromε0=137 to 1.0 keV,and converge to their maximum values asε0→0.This increase is mainly understood as coming from a longer tail of the ground-state wave function forε0≤1.0 keV,compared to that forε0=137 keV.It is also found that the effect of the continuum-continuum couplings is to slightly delay the convergence of the breakup cross section.The analysis of the reaction cross section indicates a convergence of all the breakup observables asε0→0.These results provide a better sense of the dependence of the breakup process on the breakup threshold.
基金Supported by National Natural Science Foundation of China (11035001, 11120101005, 10735010, 10975072)973 National Major State Basic Research and Development of China (2007CB815004, 2010CB327803)+2 种基金CAS Knowledge Innovation Project (KJCX2-SW-N02)Research Fund of Doctoral Point (RFDP)(20100091110028)Project Funded by Priority Academic Programme Development of Jiangsu Higher Education Institutions (PAPD)
文摘Elastic proton scattering from Be, C, and O isotopes has been investigated in the relativistic impulse approximation （RIA）. In the calculations, the nucleon-nucleus optical potentials are obtained using ground state nuclear matter densities, which are computed using the relativistic mean field model with the FSU parameter set. The scattering observables, including differential cross section, analyzing power, and spin-rotation function, are analyzed. It is found that the scattering observables for O isotopic chains display a clear mass dependence, for instance, the minimum analyzing power shifts to a low scattering angle with increasing mass number. While for the Be isotopic chain, the emergence of a neutron halo in ^（14） Be breaks this trend, i.e., the minimum analyzing powers for ^（12） Be and ^（14） Be are almost the same as each other.
基金Supported by National Basic Research Program (973 Program) of China (2007CB815002)National Natural Science Foundation of China (11035001, 10775003, 10827505, J0730316)
文摘The Halo and cluster structure at the ground state of unstable nuclei are among the most exciting phenomena of current nuclear physics. Probing these structures requires a careful selection of reaction tools. In the past twenty years, knockout reactions have been used intensively to investigate spectroscopically the structure of unstable nuclei. In this report we have illustrated the latest development of the knockout reaction tool and have emphasized the recoiled proton tagging method. A quantitative criteria is developed to evaluate the quasi-free feature of the knockout process. The newly discovered ＂towing mode＂ reaction tool is also outlined and its applicability at transit energies is discussed.
基金Supported by NSFC (91126003)the State Key Development Program of Basic Research of China (2007CB209904)
文摘Space-charge forces acting in mismatched beams have been identified as a major cause of beam halo. In this paper,we describe the beam halo experimental results in a FODO beam line at IHEP. With this beam transport line, experiments are carried out to compare the measured data with the multi-particle simulations and to study the formation of a beam halo. The maximum measured amplitudes of the matched and mismatched beam profiles agree well with simulations. Details of the experiment are presented.
