离线γ技术测量重离子熔合复合核平均角动量

THE AVERAGE ANGULAR MOMENTUM IN HEAVY-ION INDUCED FUSION REACTION BY OFF-LINE Y TECHNIQUE

使用离线Υ测量技术在质心系25.0—40.5MeV的能区测量了^(12)C+^(93)Nb熔合反应产生的二中子和三中子蒸发道的激发函数。由于在相同的激发能下,蒸发道的相对截面比与复合核的角动量有很强的依赖关系,应用统计蒸发程序(CASCADE),从二中子和三中子蒸发道的截面中提取不同能量下的复合核平均角动量和熔合截面。同时从能很好地拟合熔合激发函数的简单耦合道模型(CCFUS)计算中提取复合核的平均角动量。两种方法得到的复合核平均角动量随入射能量的变化相自洽,表明耦合道模型能同时合理地解释近垒及垒下^(12)C+^(93)Nb系统的熔合截面加强和复合核角动量分布展宽的实验结果。

Partial cross sections of two-and three-neutrons evaporation channels following the fusion reaction 12C + 93Nb have been measured for center-of-mass energies from 25.0 to 40.5 MeV by off-line 7 technique. The total fusion cross sections and average angular momenta as a function of energy have been deduced from these cross sections on the basis of statistical evaporation model calculation( CAS CADE). The fusion cross sections are well reproduced by the simplified coupled channel model (CC FUS). The average angular momenta deduced from the partial cross section ratios are consistent with that extracted from the CCFUS calculation.