摘要: 散裂反应产生的中子能谱等数据是ADS系统设计中的关键参数。由于涉及到的能量范围大、反应道复杂，目前没有完善的评价核数据库可供使用，需要使用合适的核理论模型来进行计算。CiADS （Chinainitiative Accelerator Driven System）即将开始建设，在第一阶段将使用能量约为250 MeV的质子束。利用FLUKA及GEANT4中的BERT_HP、BIC_HP和INCLXX_HP等物理模型列表分别计算了256 MeV质子轰击薄的铝、铁、铅和铀靶后，在7.5°，30°，60°和150°等方向出射的中子双微分截面及轰击厚的铝、铁和铀靶后，在30°，60°，120°和150°等方向出射的中子双微分产额，并与已有的实验数据进行对比。结果表明，FLUKA和INCLXX_HP的计算结果整体上能够更好地符合实验数据。BIC_HP计算的薄靶结果，除铝靶的150°和铅靶的30°外，在5~30 MeV能量范围内要明显高于实验结果，能够达到实验结果的2倍以上。BIC_HP计算的厚铀靶结果在30°和60°方向的5~30 MeV能量范围内要比实验结果高出70%以上，在120°和150°方向的5 MeV以上要高于实验结果的2倍。BERT_HP计算的7.5°和30°方向上铝、铁和铅靶结果在20s100 MeV要比实验结果低40%以上，计算的铀靶结果在20 MeV以下能够达到实验结果的2倍以上。


Neutron spectra produced through spallation reaction are key parameters in the design of Accelerator Driven Subcritical Systems. Since the energy span is large and reaction channels are complicated, no complete evaluated nuclear data library is ready for use. Suitable theoretical models are required to calculate the data. The CiADS (China initiative Accelerator Driven System) is going to be constructed in China. At the first stage, the adopted proton energy is about 250 MeV. FLUKA and GEANT4 are used to calculate the double differential cross sections at 7.5°, 30°, 60° and 150° induced by 256 MeV protons bombarding on thin aluminum, iron, lead and uranium targets, respectively. The double differential neutron yields at 30°, 60°, 120° and 150° are also calculated for 256 MeV protons bombarding on thick aluminum, iron and uranium targets, respectively. Three model lists INCLXX_HP, BIC_HP and BERT_HP implemented in GEANT4 are used separately. The calculation results are compared with corresponding experimental data. It is shown that results calculated with FLUKA and INCLXX_HP in GEANT4 fit the corresponding experimental data much better. The calculation results with BIC_HP overestimate the experimental data for thin targets in 5~30 MeV for more than 100%, except for aluminum at 150° and lead at 30°. For uranium target, the results calculated with BIC_HP is greater than the experimental results by more than 70% in the energy range 5~30 MeV at 30° and 60° and by more than 100% in the energy range above 5 MeV at 120° and 150°. In 20~100 MeV for aluminum, iron and lead targets, calculation results at 7.5° and 30° with BERT_HP underestimate the experimental data by more than 40%. And for uranium target, the experimental data up to 20 MeV are overestimated by more than 100%.