从实验熔合激发函数抽取势垒高度

库仑势垒在低能重离子核反应中扮演了重要的角色,但它不能被直接测量,需通过不同类型的重离子核反应间接提取。目前对库仑势垒的系统研究大都比较依赖于所采用的相互作用势模型和反应理论模型。本工作采用实验熔合截面与能量的乘积相对于能量的一阶微分作为穿透系数,并将穿透系数最大值一半的位置定义为熔合反应的经验势垒高度。该定义不依赖于理论模型,具有优秀的稳定性和可靠性。依据该定义,采用耦合道模型CCFULL及Wong公式拟合12组具有代表性的实验熔合激发函数,进而提取库仑势垒高度。通过比较本工作中从实验值抽取的势垒高度和不同理论势模型预测的势垒高度,以及其随同位旋不对称度的变化,发现Bass80和WKJ公式与本工作的结果最吻合。

Extraction of Barrier Height from Experimental Fusion Excitation Function

The Coulomb barrier plays a critical role in the low energy heavy-ion reaction. However, it can not be directly measured and needs to be extracted by different types of nuclear reactions. There have been many systematic studies on the Coulomb barrier so far, but most of them rely heavily on the interaction potential model and the reaction theory. In this work, the first-order derivative of the product of experimental fusion cross section and energy with respect to the energy was used as the penetration coefficient, and the position at which the penetration coefficient equals to half of its maximum was defined as the empirical barrier height. This definition does not depend on the theoretical model and has excellent stability and reliability. Based on this definition, the coupled-channels model CCFULL and Wong formula were used to fit 12 representative series of experimental fusion functions, and their Coulomb barrier heights were extracted. By comparing the heights extracted from the experimental values and the heights predicted by different theoretical potential models, and also their variation with the isospin asymmetry, it is found that the Bass80 and WKJ formulas are most consistent with the results of this work.