“…25 m) in preparation for measurement. Measurements of 226 Ra were performed using an ORTEC Octete Plus alpha-particle spectrometer with passivated implanted planar silicon (PIPS) detectors, which had an estimated geometrical counting efficiency of 21% (Larijani et al, 2016). The energy calibration of the detectors was performed with a mixed calibration source containing 241 Am, 244 Cm and 237 Np (Teddington, UK).…”