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Radon detection and measurement are becoming more popular due to their detrimental impacts on human health. Radon is the second leading cause of lung cancer after cigarette smoking and, in general, is the leading cause of lung cancer in people who have never smoked in their lives. The present study used a novel liquid scintillation technique to detect three naturally occurring radon isotopes (${}^{222}$Rn, ${}^{220}$Rn, and ${}^{219}$Rn) concurrently. The detection method uses the delayed coincidence technique as well as pulse shape discrimination, which is accomplished using digital charge comparison. Additionally, Monte Carlo simulations were used to determine the detector’s gamma response functions using standard ${}^{22}$Na, ${}^{60}$Co, and ${}^{137}$Cs gamma sources. Furthermore, by comparing the measured and simulated light output distributions, the detector resolution and energy calibration parameters were also determined.
Before the measurements were carried out, radon gas from the atmosphere was infused into 700 mL of Ultima Gold AB for 48 hours. The minimum detectable activities of ${}^{222}$Rn (${}^{238}$U), ${}^{220}$Rn (${}^{232}$Th), and ${}^{219}$Rn (${}^{235}$U) decay chains were determined to be 1.7, 1.0, and 1.2 mBq/L, respectively. The novel technique proposed in this study has the potential to be used to identify all three naturally occurring radon isotopes in water samples.
Thesis Advisor: Prof. Hongjoo Kim