论文标题
测量地磁北极附近的次级宇宙射线中子
Measurement of secondary cosmic-ray neutrons near the geomagnetic North Pole
论文作者
论文摘要
地球表面的宇宙中子的光谱覆盖了从热到几个GEV的宽能范围。次级中子的通量随纬度，海拔，太阳活动和附近材料（包括地面水分）而变化。 We report the results from a campaign to measure count rates in neutron detectors responding to three different energy ranges conducted near the geomagnetic North Pole at CFS Alert, Nunavut, Canada (82.5 degrees , 62.5 degrees W; vertical geomagnetic cutoff rigidity, RC = 0 GV) in June of 2016. In November 2016, we performed a follow-on measurement campaign in southern Canada at similar RC (1.5 GV）和高程。我们以不同的高程和地面水分含量进行了这些测量，并使用未修饰和调节的3HE检测器，用于热和上皮敏感性，以及EJ-299-33脉冲形状脉冲歧视塑料塑料刺激器探测器用于快速中性子。用NAI（TL）检测器监测背景伽马射线。使用这些数据集，我们将测得的计数速率与预测模型进行了比较。这是从地球上此位置获取的第一个数据集。我们发现，对于热和ev-mev中子测量值，预测模型和数据非常吻合，除了在海拔1 km附近的岩石覆盖地面上的一个位置。该位置的差异可能归因于地面水分变异性。在此运动和事先之前，其他测量值支持这样的断言，即地面水分在确定中子通量中起着至关重要的作用。
The spectrum of cosmogenic neutrons at Earth's surface covers a wide energy range, from thermal to several GeV. The flux of secondary neutrons varies with latitude, elevation, solar activity, and nearby material, including ground moisture. We report the results from a campaign to measure count rates in neutron detectors responding to three different energy ranges conducted near the geomagnetic North Pole at CFS Alert, Nunavut, Canada (82.5 degrees , 62.5 degrees W; vertical geomagnetic cutoff rigidity, RC = 0 GV) in June of 2016. In November 2016, we performed a follow-on measurement campaign in southern Canada at similar RC (1.5 GV) and elevations. We conducted these measurements, at varying elevation and ground moisture content, with unmoderated and moderated 3He detectors for thermal and epithermal-to-MeV sensitivity, and with EJ-299-33 pulse shape discrimination plastic scintillator detectors for fast neutrons. Background gamma rays were monitored with NaI(Tl) detectors. Using these data sets, we compared the measured count rates to a predictive model. This is the first ever data set taken from this location on Earth. We find that for the thermal and epithermal-to-MeV neutron measurements the predictive model and data are in good agreement, except at one location on rock-covered ground near 1 km elevation. The discrepancy at that location may be attributable to ground moisture variability. Other measurements, during this campaign and prior, support the assertion that ground moisture plays a critical role in determining neutron flux.
