The disappearance of the pfotzer‐regener maximum in dose equivalent measurements in the stratosphere
The disappearance of the pfotzer‐regener maximum in dose equivalent measurements in the stratosphere
复制标题
平流层剂量当量测量中 pfotzer-regene 最大值的消失
DOI：
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
Christopher J. Mertens
中科院分区：
文献类型：
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作者：
Alexander Hands;Keith Ryden;Christopher J. Mertens
美国宇航局辐射剂量学实验(Rad-X)成功地在高空气球上部署了四个辐射探测器，持续了大约20小时。其中一个探测器是RaySure飞行中的监测器，这是一种固态仪器，旨在测量机组人员和乘客的电离剂量率。来自Rad-X上的RaySure的数据显示，吸收剂量率作为海拔的函数稳步上升，直到大约60,000英尺的峰值，也就是众所周知的Pfotzer-Regener最大值。在这个高度以上，吸收剂量率趋于平稳，然后随着Rad-X气球接近其约125,000英尺的最大高度，出现了小幅下降。然而，生物剂量当量的情况却截然不同。在高海拔地区，来自高电离粒子的剂量比例显着增加。与较轻电离粒子的剂量相比，来自这些粒子的剂量会造成不成比例的生物损害，这反映在用于计算剂量当量的品质因数中。通过从RaySure数据计算剂量当量，使用以前校准得到的系数，我们表明在Pfotzer-Regener最大值时剂量当量率没有峰值。相反，随着初级宇宙射线剂量的影响变得越来越重要，剂量当量率随着海拔的增加而不断增加。这一结果对高空航空、太空旅游以及火星表面辐射环境都有影响，因为火星的大气层较薄。
The NASA Radiation Dosimetry Experiment (RaD‐X) successfully deployed four radiation detectors on a high‐altitude balloon for a period of approximately 20 h. One of these detectors was the RaySure in‐flight monitor, which is a solid‐state instrument designed to measure ionizing dose rates to aircrew and passengers. Data from RaySure on RaD‐X show absorbed dose rates rising steadily as a function of altitude up to a peak at approximately 60,000 feet, known as the Pfotzer‐Regener maximum. Above this altitude absorbed dose rates level off before showing a small decline as the RaD‐X balloon approaches its maximum altitude of around 125,000 feet. The picture for biological dose equivalent, however, is very different. At high altitudes the fraction of dose from highly ionizing particles increases significantly. Dose from these particles causes a disproportionate amount of biological damage compared to dose from more lightly ionizing particles, and this is reflected in the quality factors used to calculate the dose equivalent quantity. By calculating dose equivalent from RaySure data, using coefficients derived from previous calibrations, we show that there is no peak in the dose equivalent rate at the Pfotzer‐Regener maximum. Instead, the dose equivalent rate keeps increasing with altitude as the influence of dose from primary cosmic rays becomes increasingly important. This result has implications for high altitude aviation, space tourism and, due to its thinner atmosphere, the surface radiation environment on Mars.