Measurement of liquid scintillation sources of (210)Pb obtained from (222)Rn decay.
Liquid scintillation samples were filled with (222)Rn and the activity was measured with good precision after reaching the secular equilibrium with the progeny (218)Po, (214)Pb, (214)Bi and (214)Po. After decay of most of (222)Rn activity, the samples contain (210)Pb and progeny. The activities of (210)Pb and progeny can be calculated as a function of time using the initial (222)Rn activity. The samples were measured in a TDCR counter and the experimentally determined counting efficiencies are in accordance with previously published results.
A rapid method for determining low concentrations of 210Pb in drinking water using MnO2 fibers.
A rapid method for determining low activity concentrations of 210Pb in drinking water was developed and tested. The method consists of a few stages for sample preparation that involve passing 12 L of water through a column with acrylic fibers implanted with MnO2 (used to adsorb 210Pb). The MnO2 fibers are oven-dried, compressed and measured by a broad-energy germanium detector used to quantify 210Pb via its characteristic 46.5 keV γ-ray. The time taken for sample preparation is approximately 4 h and recovery factors for lead in tap water of 87 ± 3% were achieved. After a measurement duration of 4 h, the minimum detectable activity concentration reaches 0.02 Bq/L for 210Pb, being well below the respective limit for drinking water in Israel (0.2 Bq/L) as well as the value recommended by the World Health Organization (0.1 Bq/L). Furthermore, a measurement duration of 48 h provides a minimum detectable activity concentration of ∼0.006 Bq/L, which is similar in magnitude to other, well-established methods that rely on lengthy and rather complex procedures. Thus, the combination of MnO2 fibers and gamma-ray spectrometry may be attractive for routine use by analytical laboratories that monitor radioactivity in drinking water.
Transfer of the efficiency calibration of Germanium gamma-ray detectors using the GESPECOR software.
The GESPECOR software was extended to incorporate procedures for the computation of the efficiency transfer factor for cases of practical interest: (a) sources with identical geometry, but different matrices, (b) sources with similar (but not identical) geometry; and (c) transfer from a point source to a volume source. Fast and accurate algorithms. based on correlated sampling, were implemented for solving the first two cases. A procedure to take into account the imperfect charge collection in the detector was implemented.