Neutron-impact single and double ionization cross sections of the He atom are calculated near the neutron-alpha particle collision resonance. Calculations using the time-dependent close-coupling method for total and differential cross sections are made at 8 incident neutron energies ranging from 250 to 2000 keV. At the resonance energy peak the double ionization cross sections unexpectedly become larger than the single ionization cross sections. This finding appears to be related to the high velocity of the recoiling alpha particle, which makes it unlikely that the atomic electrons can recombine with the alpha particle nucleus, enhancing the double ionization cross section.

中文翻译：

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氦在中子-α粒子碰撞共振附近的中子电离

在中子-α粒子碰撞共振附近计算He原子的中子碰撞单电离和双电离截面。在总入射角和微分截面的8个入射中子能量为250到2000 keV的情况下，使用时间依赖的闭合耦合方法进行了总截面和微分截面的计算。在共振能量峰值处，双电离截面意外地变得大于单电离截面。这一发现似乎与反冲α粒子的高速有关，这使得原子电子不可能与α粒子核复合，从而增强了双电离截面。