μDose: a compact system for environmental radioactivity and dose rate measurement

Abstract: $\mu$Dose is a novel compact analytical instrument for assessing low level $^{238}$U, $^{235}$U, $^{232}$Th decay chains and $^{40}$K radioactivity. The system is equipped with a dual $\alpha$/$\beta$ scintillator allowing to discriminate between $\alpha$ and $\beta$ particles. The unique build-in pulse analyzer measures the amplitude of each individual pulse, its shape and the time interval between subsequent pulses. This allows the detection of pulse pairs arising from subsequent decays of $^{214}$Bi/$^{214}$Po, $^{220}$Rn/$^{216}$Po, $^{212}$Bi/$^{212}$Po and $^{219}$Rn/$^{215}$Po. The obtained $\alpha$ and $\beta$ counts and four separate decay pair counts are used to asses the $^{238}$U, $^{235}$U, $^{232}$Th and $^{40}$K specific radioactivities in the measured samples through the use of radioactivity standards. The $\mu$Dose system may be equipped with various photomultipliers and counting containers to assess radionuclide concentrations of samples of masses ranging between 0.4~g and 4~g. As a result, the user can customize the system to their needs and maximize the instrument\textquotesingle s performance. The system is controlled by a dedicated software with a graphical user interface and modules for system calibration, data visualization, specific radioactivity calculations and dose rate determination using the infinite matrix assumption.