Elliptic flow （v2） and hexadecupole flow （v4） of light clusters have been studied in detail for 25 MeV/nucleon ^86Kr ＋ ^124Sn at large impact parameters by using a quantum molecular dynamics model with different ...Elliptic flow （v2） and hexadecupole flow （v4） of light clusters have been studied in detail for 25 MeV/nucleon ^86Kr ＋ ^124Sn at large impact parameters by using a quantum molecular dynamics model with different potential parameters. Four sets of parameters including soft or hard equation of state （EOS） with or without symmetry energy term are used. Both number-of-nucleon （A） scaling of the elliptic flow versus transverse momentum （Pt） and the scaling of v4/A^2 versus （pt/A）^2 have been demonstrated for the light clusters in all above calculation conditions. It is also found that the ratio of v4/v2^2 maintains a constant of 1/2 which is independent of pt for all the light fragments. Comparisons among different combinations of the EOS and the symmetry potential term show that the above scaling behaviours are sound and independent of the details of potential, while the strengths of flows are sensitive to the EOS and the symmetry potential term.展开更多
Anisotropic flows （v1, v2, v3 and v4） of light fragments up to the mass number 4 as a function of rapidity are studied for 25 MeV/nucleon ^40Ca ＋ ^40Ca at large impact parameters by a quantum molecular dynamics mod...Anisotropic flows （v1, v2, v3 and v4） of light fragments up to the mass number 4 as a function of rapidity are studied for 25 MeV/nucleon ^40Ca ＋ ^40Ca at large impact parameters by a quantum molecular dynamics model. A phenomenological scaling behaviour of rapidity dependent flow parameters vn （n = 1, 2, 3 and 4） is found as a function of mass number plus a constant term, which may arise from the interplay of collective and random motions. In addition, v4/v2^2 keeps to be almost independent of rapidity and remains a rough constant of 1/2 for all light fragments.展开更多
Anisotropic flows per nucleon （v1/A, v2/A, v3/A and v4/A） of light fragments up to the mass number 4 as a function of transverse momentum per nucleon are studied for 55 Me V/nucleon 58Fe＋58Fe and 58 Ni＋ 58 Ni at l...Anisotropic flows per nucleon （v1/A, v2/A, v3/A and v4/A） of light fragments up to the mass number 4 as a function of transverse momentum per nucleon are studied for 55 Me V/nucleon 58Fe＋58Fe and 58 Ni＋ 58 Ni at large impact parameters by the isospin-dependent quantum molecular dynamics model. The effects of symmetry energy and nucleon-nucleon cross sections, which are both isospin-dependent on anisotropic flows, are studied in detail. In comparison of the two systems with or without symmetry potential term, the results show that the strength of flows is sensitive to symmetry potential and nucleon-nucleon cross sections, which mainly cause a repulsion effect in this energy region.展开更多
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10535010 and 10610285）, the Shanghai Development Foundation for Science and Technology of China （Grant Nos 06JC14082 and 05XD14021）, and Chinese Academy of Sciences project （Grant No KJCX3.SYW.N2）.
文摘Elliptic flow （v2） and hexadecupole flow （v4） of light clusters have been studied in detail for 25 MeV/nucleon ^86Kr ＋ ^124Sn at large impact parameters by using a quantum molecular dynamics model with different potential parameters. Four sets of parameters including soft or hard equation of state （EOS） with or without symmetry energy term are used. Both number-of-nucleon （A） scaling of the elliptic flow versus transverse momentum （Pt） and the scaling of v4/A^2 versus （pt/A）^2 have been demonstrated for the light clusters in all above calculation conditions. It is also found that the ratio of v4/v2^2 maintains a constant of 1/2 which is independent of pt for all the light fragments. Comparisons among different combinations of the EOS and the symmetry potential term show that the above scaling behaviours are sound and independent of the details of potential, while the strengths of flows are sensitive to the EOS and the symmetry potential term.
基金Supported partially by the National Basic Research Programme of China under Contract No 2007CB815004, the Shanghai Development Foundation from Science and Technology under Grant Nos 06JC14082 and 06QA14062, the National Natural Science Foundation of China under Grant Nos 10535010 and 10775167.
文摘Anisotropic flows （v1, v2, v3 and v4） of light fragments up to the mass number 4 as a function of rapidity are studied for 25 MeV/nucleon ^40Ca ＋ ^40Ca at large impact parameters by a quantum molecular dynamics model. A phenomenological scaling behaviour of rapidity dependent flow parameters vn （n = 1, 2, 3 and 4） is found as a function of mass number plus a constant term, which may arise from the interplay of collective and random motions. In addition, v4/v2^2 keeps to be almost independent of rapidity and remains a rough constant of 1/2 for all light fragments.
文摘Anisotropic flows per nucleon （v1/A, v2/A, v3/A and v4/A） of light fragments up to the mass number 4 as a function of transverse momentum per nucleon are studied for 55 Me V/nucleon 58Fe＋58Fe and 58 Ni＋ 58 Ni at large impact parameters by the isospin-dependent quantum molecular dynamics model. The effects of symmetry energy and nucleon-nucleon cross sections, which are both isospin-dependent on anisotropic flows, are studied in detail. In comparison of the two systems with or without symmetry potential term, the results show that the strength of flows is sensitive to symmetry potential and nucleon-nucleon cross sections, which mainly cause a repulsion effect in this energy region.
