【摘要】 假定⁸Be是由两个在组态空间相邻的α粒子组成的,因而获得在余核中⁸Be集团的谱密度正比于核表面α粒子预形成几率P_α的平方。利用改进了的EFRDWBA重叠积分的参数化方法,我们计算了²⁰⁹Bi(¹²C,α)²¹⁷Fr反应中出射的α粒子的角分布和双微分能谱,而且通过拟合实验数据提取了在²¹⁷Fr核表面的α粒子的预形成几率,结果与由α衰变数据提取的预形成几率在计算误差范围内一致。这个事实说明,²⁰⁹Bi(¹²C,α)²¹⁷Fr可能是双α直接转移反应。更多还原

【Abstract】 It is assumed that ⁸Be consists of two α-particles which are close to each other in configration space. A spectroscopic density of ⁸Be-cluster in the residue nuclei is then obtained which is proportional to the square of the preformation probability of α-particle at nuclear surface. Using the improved method of parametrization of EFR-DWBA overlap integral, We calculate the double diffirential energy spectra and angular distributions of α-particles for the reactions ²⁰⁹Bi (¹²C,α) ²¹⁷Fr and extracte the preformation probability of α-particle at the surface of ²¹⁷Fr nuclei from fitting the experimental data. The agreement within the range of calculation error between the preformation probabilities extracted from transfer reactions and α-decay suggests that the reaction ²⁰⁹Bi(^l2C,α) ^2l7 Fr may be explained as a double α direct transfer process.更多还原