Systematics of fusion-fission time scales.
Systematics of fusion-fission time scales.
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DOI：
10.1103/physrevc.39.2268
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发表时间：
1989-06
期刊：
影响因子：
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通讯作者：
Hinde;Ogata;Tanaka;Shimoda;Takahashi;Shinohara;Wakamatsu;Katori;Okamura
中科院分区：
文献类型：
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作者：
Hinde;Ogata;Tanaka;Shimoda;Takahashi;Shinohara;Wakamatsu;Katori;Okamura
新的裂变前中子多重性（... nu../给出了/sup 7/Li-、/sup 16/O-和/sup 20/Ne诱发裂变的sub pre/）数据，裂变度范围为0.60 - 0.85。裂变时间尺度已经推导出两个极端的假设，在裂变过程中的平均激发能。发现对于聚变-裂变反应，裂变时标与裂变度无关，在1.5倍以内。从... nu../根据复合系统的旋转角推导出的准裂变时间尺度的快裂变的子预/测量允许确定30/times/10/sup /minus/21/ s的最小聚变-裂变时间尺度。对于最易裂变的系统，快裂变（没有势垒的裂变）被证明比聚变裂变快三倍。使用一个模型来解释聚变-裂变的时间尺度，它的结论是，在裂变方向上的运动是强烈过阻尼。这意味着裂变的动力学是由一个缓慢的扩散到分裂，而不是由势能面。它表明，这样的图片可以解释所观察到的缺乏依赖的裂变时间尺度上的裂变。
New pre-scission neutron multiplicity (..nu../sub pre/) data for /sup 7/Li-, /sup 16/O-, and /sup 20/Ne-induced fission are presented, spanning a fissility range from 0.60 to 0.85. Fission time scales have been deduced for two extreme assumptions regarding the mean excitation energy during fission. It is found for fusion-fission reactions that the fission time scale is independent of fissility, within a factor 1.5. A comparison of time scales deduced from ..nu../sub pre/ measurements for fast-fission with quasifission time- scales deduced from the rotation angle of the composite system allows a minimum fusion-fission time scale of 30/times/10/sup /minus/21/ s to be determined. For the most fissile system, fast-fission (fission without barrier) is shown to be up to three times faster than fusion-fission. Using a model to interpret the fusion-fission time scales, it is concluded that motion in the fission direction is strongly overdamped. This means that the dynamics of fission are dominated by a slow diffusion towards scission, and not by the potential energy surface. It is shown that such a picture can explain the observed lack of dependence of the fission time scale on fissility.