Recent progress of the quantum molecular dynamics model for describing the dynamics of heavy-ion collisions is viewed, in particular the nuclear fragmentation, isospin physics, particle production and in-medium effect...Recent progress of the quantum molecular dynamics model for describing the dynamics of heavy-ion collisions is viewed, in particular the nuclear fragmentation, isospin physics, particle production and in-medium effect, hadron-induced nuclear reactions, hypernucleus, etc.The neck fragmentation in Fermi-energy heavy-ion collisions is investigated for extracting the symmetry energy at subsaturation densities. The isospin effects, in-medium properties, and the behavior of high-density symmetry energy in medium-and high-energy heavy-ion collisions are thoroughly discussed. The hypernuclide dynamics formed in heavy-ion collisions and in hadron-induced reactions is analyzed and addressed in the future experiments at the high-intensity heavy-ion accelerator facility(HIAF).展开更多
In this work, the neutron radiation field at Heavy Ion Research Facility in Lanzhou （HIRFL） was investigated. Total neutron yields, spectra and angular distributions in the bombardment of various thick targets by 12...In this work, the neutron radiation field at Heavy Ion Research Facility in Lanzhou （HIRFL） was investigated. Total neutron yields, spectra and angular distributions in the bombardment of various thick targets by 12C and ^18O ions with energies up to 75 MeV/u were obtained using the activation method. The neutron dose equivalent rates of 60 MeV/u ^18O on various thick targets at different angles were measured with a modified A-B remmeter. Our results are compared with those of other reports.展开更多
The Efimov(Thomas) trimers in excited 12 C nuclei, for which no observation exists yet, are discussed by means of analyzing the experimental data of 70(64)Zn(64 Ni)+ 70(64)Zn(64 Ni) reactions at the beam energy of E/A...The Efimov(Thomas) trimers in excited 12 C nuclei, for which no observation exists yet, are discussed by means of analyzing the experimental data of 70(64)Zn(64 Ni)+ 70(64)Zn(64 Ni) reactions at the beam energy of E/A = 35 MeV/nucleon. In heavy ion collisions, a-particles interact with each other and can form complex systems such as 8 Be and 12 C. For the 3 a-particle systems,multi-resonance processes give rise to excited levels of 12 C. The interaction between any two of the 3 a-particles provides events with one, two or three 8 Be. Their interfering levels are clearly seen in the minimum relative energy distributions. Events with the three a-particle relative energies consistent with the ground state of 8 Be are observed with the decrease of the instrumental error for the reconstructed 7.458 MeV excitation level in 12 C, which was suggested as the Efimov(Thomas) state.展开更多
An improved method is proposed for the extraction of the symmetry energy coefficient relative to the temperature, asym/T, for the heavy-ion reactions near the Fermi energy region, based on the modified Fisher Model(MF...An improved method is proposed for the extraction of the symmetry energy coefficient relative to the temperature, asym/T, for the heavy-ion reactions near the Fermi energy region, based on the modified Fisher Model(MFM). This method is applied to the primary fragments of the Anti-symmetrized Molecular Dynamics(AMD)simulations for the reactions of40 Ca + 40 Ca at 35 Me V/nucleon. The density and the temperature at the fragment formation stage are extracted using a self-consistent method.展开更多
Within the quantum molecular dynamics （QMD） model, the dynamical octupole deformation is studied as a function of the central distance between the projectile and target in the approaching process of heavy-ion fusion...Within the quantum molecular dynamics （QMD） model, the dynamical octupole deformation is studied as a function of the central distance between the projectile and target in the approaching process of heavy-ion fusion reactions. The dependence of the maximum dynamical octupole defor- mations on tile incident energies is also investigated. The dynamical octupole deformations can be observed during the approaching process, and the maximum dynamical octupole deformations be- come more significant with decreasing incident energies. The distributions of the proton and neutron centers in the projectile and target are also investigated, respectively. In the approaching process of heavy-ion fusion reactions, the separation between proton centers for two nuclei is larger than that between neutron centers because of the strong Coulomb potential.展开更多
Identified particle elliptic flow results are presented for the Au+Au reaction at S_(NN)^(1/2)=200GeV as a function of transverse momentum and pseudorapidity.Data at pseudorapiditiesη≈0,1,and 3.4 were obtained using...Identified particle elliptic flow results are presented for the Au+Au reaction at S_(NN)^(1/2)=200GeV as a function of transverse momentum and pseudorapidity.Data at pseudorapiditiesη≈0,1,and 3.4 were obtained using the two BRAHMS spectrometers.Differential v_2(η,p_t)values for a given particle type are found to be essentially constant over the covered pseudorapidity range,in contrast to the integral v_2 values which have previously been observed to decrease at forward rapidities.A softening of the particle spectra at forward angles is found to account for at least part of the integral v_2 falloff.The data are found to be consistent with existing constituent quark scaling systematics.展开更多
We discussed recent studies, within the framework of transport theories, on heavy ion reactions between charge asymmetric systems, from low up to Fermi energies. We concentrated on the analysis of ternary breakup even...We discussed recent studies, within the framework of transport theories, on heavy ion reactions between charge asymmetric systems, from low up to Fermi energies. We concentrated on the analysis of ternary breakup events of dynamical origin occurring in semi-central reactions, where the formation of excited systems in various conditions of shape, excitation energy and spin is observed. At beam energies around 20 A Me V, we showed how this fragmentation mode emerges from the combined action of surface(neck) instabilities and angular momentum effects, leading to the observation of three aligned massive fragments in the exit channel. At Fermi energies, a transition towards a prompt emission of small fragments from the neck region with larger relative velocity with respect to projectile and target remnants is observed. We also focus on isospin sensitive observables, aiming at extracting information on the density dependence of the isovector part of the nuclear effective interaction and of the nuclear symmetry energy.展开更多
基金supported by the National Natural Science Foundation of China(Nos.11675226 and 11722546)the Major State Basic Research Development Program of China(Nos.2014CB845405 and 2015CB856903)
文摘Recent progress of the quantum molecular dynamics model for describing the dynamics of heavy-ion collisions is viewed, in particular the nuclear fragmentation, isospin physics, particle production and in-medium effect, hadron-induced nuclear reactions, hypernucleus, etc.The neck fragmentation in Fermi-energy heavy-ion collisions is investigated for extracting the symmetry energy at subsaturation densities. The isospin effects, in-medium properties, and the behavior of high-density symmetry energy in medium-and high-energy heavy-ion collisions are thoroughly discussed. The hypernuclide dynamics formed in heavy-ion collisions and in hadron-induced reactions is analyzed and addressed in the future experiments at the high-intensity heavy-ion accelerator facility(HIAF).
文摘In this work, the neutron radiation field at Heavy Ion Research Facility in Lanzhou （HIRFL） was investigated. Total neutron yields, spectra and angular distributions in the bombardment of various thick targets by 12C and ^18O ions with energies up to 75 MeV/u were obtained using the activation method. The neutron dose equivalent rates of 60 MeV/u ^18O on various thick targets at different angles were measured with a modified A-B remmeter. Our results are compared with those of other reports.
基金Supported by the National Natural Science Foundation of China(1176014,11605097,11421505,11865010)the US Department of Energy(DE-FG02-93ER40773,NNSA DE-NA0003841(CENTAUR))+6 种基金the Robert A.Welch Foundation(A-1266)supported by the Chinese Academy of Sciences(CAS)President’s International Fellowship Initiative(2015VWA070)Strategic Priority Research Program of the Chinese Academy of Sciences(XDB16 and XDPB09)Program for Young Talents of Science and Technology in Universities of Inner Mongolia Autonomous Region(NJYT-18-B21)Doctoral Scientific Research Foundation of Inner Mongolia University for Nationalities(BS365 and BS400)The Fundamental Research Funds for the Central Universities(GK201903022)Natural Science Foundation of Inner Mongolia(2018MS01009)
文摘The Efimov(Thomas) trimers in excited 12 C nuclei, for which no observation exists yet, are discussed by means of analyzing the experimental data of 70(64)Zn(64 Ni)+ 70(64)Zn(64 Ni) reactions at the beam energy of E/A = 35 MeV/nucleon. In heavy ion collisions, a-particles interact with each other and can form complex systems such as 8 Be and 12 C. For the 3 a-particle systems,multi-resonance processes give rise to excited levels of 12 C. The interaction between any two of the 3 a-particles provides events with one, two or three 8 Be. Their interfering levels are clearly seen in the minimum relative energy distributions. Events with the three a-particle relative energies consistent with the ground state of 8 Be are observed with the decrease of the instrumental error for the reconstructed 7.458 MeV excitation level in 12 C, which was suggested as the Efimov(Thomas) state.
基金Supported by the National Natural Science Foundation of China(Nos.11075189 and 11205209)100 Persons Project(Nos.0910020BR0and Y010110BR0)+2 种基金ADS project 302(No.Y103010ADS)of the Chinese Academy of Sciencesthe U.S.Department of Energy(No.DE-FG03-93ER40773)the Robert A.Welch Foundation(No.A0330)
文摘An improved method is proposed for the extraction of the symmetry energy coefficient relative to the temperature, asym/T, for the heavy-ion reactions near the Fermi energy region, based on the modified Fisher Model(MFM). This method is applied to the primary fragments of the Anti-symmetrized Molecular Dynamics(AMD)simulations for the reactions of40 Ca + 40 Ca at 35 Me V/nucleon. The density and the temperature at the fragment formation stage are extracted using a self-consistent method.
基金The work was supported by the Na- tional Natural Science Foundation of China （Crant Nos. 11475115, 10975100, 11275098, 10979066, and 11120101005）, the National Basic Research Program of Ministry of Science and Technology of China （Grant No. 2007CB815000）, the Knowledge Innovation Project of CAS （Crant Nos. KJCX2-EW-N01 and KJCX2-YW- N32）. Part of the numerical results is obtained on the ScCrid of Supercomputing Center, CNIC of CAS.
文摘Within the quantum molecular dynamics （QMD） model, the dynamical octupole deformation is studied as a function of the central distance between the projectile and target in the approaching process of heavy-ion fusion reactions. The dependence of the maximum dynamical octupole defor- mations on tile incident energies is also investigated. The dynamical octupole deformations can be observed during the approaching process, and the maximum dynamical octupole deformations be- come more significant with decreasing incident energies. The distributions of the proton and neutron centers in the projectile and target are also investigated, respectively. In the approaching process of heavy-ion fusion reactions, the separation between proton centers for two nuclei is larger than that between neutron centers because of the strong Coulomb potential.
基金Supported by the Office of Nuclear Physics of the U.S.Department of Energy under contract DE-FG03-96ER40981
文摘Identified particle elliptic flow results are presented for the Au+Au reaction at S_(NN)^(1/2)=200GeV as a function of transverse momentum and pseudorapidity.Data at pseudorapiditiesη≈0,1,and 3.4 were obtained using the two BRAHMS spectrometers.Differential v_2(η,p_t)values for a given particle type are found to be essentially constant over the covered pseudorapidity range,in contrast to the integral v_2 values which have previously been observed to decrease at forward rapidities.A softening of the particle spectra at forward angles is found to account for at least part of the integral v_2 falloff.The data are found to be consistent with existing constituent quark scaling systematics.
基金Supported by a grant of the Romanian National Authority for Scientific Research,CNCS-UEFISCDI(No.PN-II-ID-PCE-2011-3-0972)
文摘We discussed recent studies, within the framework of transport theories, on heavy ion reactions between charge asymmetric systems, from low up to Fermi energies. We concentrated on the analysis of ternary breakup events of dynamical origin occurring in semi-central reactions, where the formation of excited systems in various conditions of shape, excitation energy and spin is observed. At beam energies around 20 A Me V, we showed how this fragmentation mode emerges from the combined action of surface(neck) instabilities and angular momentum effects, leading to the observation of three aligned massive fragments in the exit channel. At Fermi energies, a transition towards a prompt emission of small fragments from the neck region with larger relative velocity with respect to projectile and target remnants is observed. We also focus on isospin sensitive observables, aiming at extracting information on the density dependence of the isovector part of the nuclear effective interaction and of the nuclear symmetry energy.
