A study of raining influence on the environmental radiation background spectra with HXMT/HE

TL;DR

This study investigates how rainfall influences the environmental radiation background spectra detected by HXMT/HE, revealing that radon decay products in rainwater cause transient spectral changes and confirming the detectors' sensitivity and calibration effectiveness.

Contribution

The paper identifies rainwater radon decay products as the cause of transient background spectral changes in HXMT/HE detectors, demonstrating their sensitivity and calibration accuracy.

Findings

Rainfall causes transient increases in background spectra due to radon decay products.

HXMT/HE detectors are sensitive to environmental radiation changes.

Calibration of detectors remains effective despite environmental variations.

Abstract

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.