Shinn J L, Cucinotta F A, Wilson J W, Badhwar G D, O'Neill P M, Badavi F F
NASA Langley Research Center, Hampton, VA 23681-0001, USA.
IEEE Trans Nucl Sci. 1995 Dec;42(6):2017-25. doi: 10.1109/23.489248.
Recent improvements in the radiation transport code HZETRN/BRYNTRN and galactic cosmic ray environmental model have provided an opportunity to investigate the effects of target fragmentation on estimates of single event upset (SEU) rates for spacecraft memory devices. Since target fragments are mostly of very low energy, an SEU prediction model has been derived in terms of particle energy rather than linear energy transfer (LET) to account for nonlinear relationship between range and energy. Predictions are made for SEU rates observed on two Shuttle flights, each at low and high inclination orbit. Corrections due to track structure effects are made for both high energy ions with track structure larger than device sensitive volume and for low energy ions with dense track where charge recombination is important. Results indicate contributions from target fragments are relatively important at large shield depths (or any thick structure material) and at low inclination orbit. Consequently, a more consistent set of predictions for upset rates observed in these two flights is reached when compared to an earlier analysis with CREME model. It is also observed that the errors produced by assuming linear relationship in range and energy in the earlier analysis have fortuitously canceled out the errors for not considering target fragmentation and track structure effects.
辐射输运代码HZETRN/BRYNTRN和银河宇宙射线环境模型最近的改进，为研究目标碎片对航天器存储设备单粒子翻转（SEU）率估计的影响提供了契机。由于目标碎片大多能量极低，因此已根据粒子能量而非线能量转移（LET）推导了一个SEU预测模型，以考虑射程与能量之间的非线性关系。针对在两次航天飞机飞行中观察到的SEU率进行了预测，每次飞行分别处于低倾角轨道和高倾角轨道。对于径迹结构大于器件灵敏体积的高能离子以及电荷复合很重要的密径迹低能离子，都进行了径迹结构效应的修正。结果表明，在大屏蔽深度（或任何厚结构材料）以及低倾角轨道处，目标碎片的贡献相对重要。因此，与早期使用CREME模型的分析相比，对于这两次飞行中观察到的翻转率，得到了一组更一致的预测。还观察到，早期分析中假设射程与能量呈线性关系所产生的误差，偶然地抵消了未考虑目标碎片和径迹结构效应所产生的误差。
