Badhwar G D, Cucinotta F A, Braby L A, Konradi A
NASA Johnson Space Center, Houston, Texas 77058-3696.
Radiat Res. 1994 Sep;139(3):344-51.
A new class of tissue-equivalent proportional counters has been flown on two space shuttle flights. These detectors and their associated electronics cover a lineal energy range from 0.4 to 1250 keV/microns with a multichannel analyzer resolution of 0.1 keV/microns from 0.4 to 20 keV/microns and 5 keV/microns from 20 to 1250 keV/microns. These detectors provide the most complete dynamic range and highest resolution of any technique currently in use. On one mission, one detector was mounted in the Shuttle payload bay and another older model in the mid-deck, thus providing information on the depth dependence of the lineal energy spectrum. A detailed comparison of the observed lineal energy and calculated LET spectra for galactic cosmic radiation shows that, although the radiation transport models provide a rather accurate description of the dose (+/- 15%) and equivalent dose (+/- 15%), the calculations significantly underestimate the frequency of events below about 100 keV/microns. This difference cannot be explained by the inclusion of the contribution of splash protons. The contribution of the secondary pions, kaons and electrons produced in the Shuttle shielding, if included in the radiation transport model, may explain these differences. There are also significant differences between the model predictions and observations above 140 keV/microns, particularly for 28.5 degrees inclination orbit.
一类新型的组织等效正比计数器已搭载在两次航天飞机飞行任务中。这些探测器及其相关电子设备覆盖的线能量范围为0.4至1250 keV/微米，多通道分析仪在0.4至20 keV/微米范围内的分辨率为0.1 keV/微米，在20至1250 keV/微米范围内的分辨率为5 keV/微米。这些探测器提供了目前使用的任何技术中最完整的动态范围和最高的分辨率。在一次任务中，一个探测器安装在航天飞机的有效载荷舱内，另一个较旧型号安装在中层甲板上，从而提供了关于线能量谱深度依赖性的信息。对银河系宇宙辐射观测到的线能量和计算得到的传能线密度（LET）谱的详细比较表明，尽管辐射传输模型对剂量（±15%）和当量剂量（±15%）提供了相当准确的描述，但计算结果显著低估了约100 keV/微米以下事件的频率。这种差异不能通过计入溅射中质子的贡献来解释。如果在辐射传输模型中计入航天飞机屏蔽层中产生的次级π介子、K介子和电子的贡献，可能会解释这些差异。在140 keV/微米以上，模型预测和观测结果之间也存在显著差异，特别是对于28.5度倾斜轨道。
