Heilbronn L, Cary R S, Cronqvist M, Deak F, Frankel K, Galonsky A, Holabird K, Horvath A, Kiss A, Kruse J, Ronningen R M, Schelin H, Seres Z, Stronach C E, Wang J, Zecher P, Zeitlin C
Lawrence Berkeley National Laboratory, Berkeley, California, 94720, USA.
Nucl Sci Eng. 1999 May;132(1):1-15. doi: 10.13182/nse98-41.
Neutron fluences have been measured from 155 MeV/nucleon 4He and 12C ions stopping in an Al target at laboratory angles between 10 and 160 deg. The resultant spectra were integrated over angle and energy above 10 MeV to produce total neutron yields. Comparison of the two systems shows that approximately two times as many neutrons are produced from 155 MeV/nucleon 4He stopping in Al and 155 MeV/nucleon 12C stopping in Al. Using an energy-dependent geometric cross-section formula to calculate the expected number of primary nuclear interactions shows that the 12C + Al system has, within uncertainties, the same number of neutrons per interaction (0.99 +/- 0.03) as does the 4He + Al system (1.02 +/- 0.04), despite the fact that 12C has three times as many neutrons as does 4He. Energy and angular distributions for both systems are also reported. No major differences can be seen between the two systems in those distributions, except for the overall magnitude. Where possible, the 4He + Al spectra are compared with previously measured spectra from 160 and 177.5 MeV/nucleon 4He interactions in a variety of stopping targets. The reported spectra are consistent with previously measured spectra. The data were acquired to provide data applicable to problems dealing with the determination of the radiation risk to humans engaged in long-term missions in space; however, the data are also of interest for issues related to the determination of the radiation environment in high-altitude flight, with shielding at high-energy heavy-ion accelerators and with doses delivered outside tumor sites treated with high-energy hadronic beams.
已经测量了能量为155 MeV/核子的4He和12C离子在铝靶中停止时，在实验室角度10°至160°之间的中子注量。将所得能谱在角度和能量高于10 MeV的范围内进行积分，以产生总中子产额。对这两个系统的比较表明，能量为155 MeV/核子的4He在铝中停止时产生的中子数量大约是能量为155 MeV/核子的12C在铝中停止时产生中子数量的两倍。使用能量依赖的几何截面公式来计算预期的初级核相互作用数量表明，尽管12C的中子数量是4He的三倍，但12C + Al系统在不确定度范围内，每次相互作用产生的中子数量（0.99±0.03）与4He + Al系统（1.02±0.04）相同。还报告了两个系统的能量和角度分布。除了整体幅度外，在这些分布中两个系统之间没有明显差异。在可能的情况下，将4He + Al能谱与先前测量的能量为160和177.5 MeV/核子的4He在各种停止靶中的相互作用能谱进行了比较。报告的能谱与先前测量的能谱一致。获取这些数据是为了提供适用于处理确定长期太空任务中人类辐射风险问题的数据；然而，这些数据对于与确定高空飞行中的辐射环境、高能重离子加速器的屏蔽以及高能强子束治疗肿瘤部位之外的剂量相关的问题也很有意义。
