摘要:
从35 MeV/nucleon40Ca+40Ca反应实验数据中提取了碎片Z从1到9的横向流,发现探测器阈值、探测系统的角分辨等实验条件对横向流电荷依赖的形状有显著的影响.在考虑实验条件并采用软的核物质状态方程(K=200 MeV)之后,CoMD模型计算结果很好地重现了实验中横向流电荷依赖的形状.这表明如果要更加精确地提取实验中的横向流,必须使用阈值更低、角分辨更好的探测系统.此外,结合Kohley等[Phys Rev C,2012,85:064605]从实验中提取的横向流,讨论了横向流电荷依赖的形状存在异同的原因.1≤Z≤6的横向流电荷依赖呈肩峰形状可能是实验条的影响引起的,而我们的实验中Z≥6的横向流的减小可能是由于动量守恒对集体运动的抑制.
Abstract:
The transverse flow in the reaction of 40Ca+40Ca at 35 MeV/nucleon has been determined for emitted isotopes with Z =1 to 9.A significant modification of the Z-dependent flow pattern caused by the experimental filters,the detector thresholds and the angular resolutions (△φ) of the detector array,is observed.With the application of the appropriate experimental filters,the general trend of the experimental Z-dependent flow is well reproduced by the Constrained Molecular Dynamics (CoMD) simulation,employing an effective interaction corresponding to a soft EOS (K =200 MeV).This fact suggests that to determine the flow values more precisely,a detection system with lower energy threshold and better angular resolution is urgently required.Additionally,together with the parallel work of Z.Kohley et al.[Phys Rev C,2012,85:064605],the pattern of the experimental Z dependence of transverse flow is also discussed.The shoulder patterns of Z-dependent flow for 1 ≤ Z ≤ 6 can be attributed by the experimental filters,while the reduction of flow for Z ≥ 6 in our experiment can be caused by the suppression of collective motion under the momentum conservation.
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