The Threshold Anomaly Of Optical Potentials And The Dispersion Relation For Weakly-bound Nuclear Systems
Chia–Chin Lin, Lanlan Yang, H. M. Jia, D. X. Wang, N. R., L. J. Sun, F. Yang, Zijun Wu, X. X. Xu, H. Q. Zhang, ziwei liu · Proceedings of The 26th International Nuclear Physics Conference (INPC2016). 11-16 September · 2016
Angular distributions of transfer reaction $^{208}$Pb($^{7}$Li,$^{6}$He)$^{209}$Bi were measured at $E_{\mathrm{lab}}$($^7$Li) = 21.2, 24.3, 25.67, 28.55, 32.55, 37.55 and 42.55 MeV. By fitting the experimental data with the theoretical frameworks of Distorted Wave Born Approximation (DWBA), the optical model parameters of halo nuclear system $^{6}$He + $^{209}$Bi were extracted. The breakup threshold anomaly (BTA) was observed clearly in the imaginary potential, and a further decreasing trend in the deep sub-barrier region was observed for the first time in a halo system. Furthermore, the dispersion relation is found of no use to describe the connection between the real and imaginary parts.