A study of raining influence on the environmental radiation background   spectra with HXMT/HE
  Full functional and performance tests were performed many times before the Hard X-ray Modulation Telescope (HXMT) launch. During one of the tests, the count rate curves of the 18 High Energy Detectors (HED) have been found increased consistently within an interval of time. A further study on the correlation between the count rate and rainfall was carried out,and the increased net spectrum was also analyzed. The analysis results indicate that the short-lived 222Rn decay products (214Pb and 214Bi) in rainwater were responsible for the transient changes of the background radiation spectra in HEDs. The results show that the HXMT/HEDs have a good detection sensitivity on X/gamma rays, and the detector calibration results are effective. 
Xu-Fang Li, Cong-Zhan Liu, Yi-Fei Zhang, Zheng-Wei Li, Xue-Feng Lu,   Jian-Ling Zhao, Chang-Lin Zou, Yu-Peng Xu, Fang-Jun Lu
physics.ins-det astro-ph.IM nucl-ex