Calibration of spectrometric detectors for air kerma rates in environmental monitoring

The spectrometric systems, especially based on NaI(Tl) and HPGe detectors, are used for nuclide identification and calculation of their activities from the ground measurements and air-borne monitoring. The determination of the air kerma (dose) rates is also very important for environmental measurements. In such cases, the detectors should be calibrated for air kerma (dose) rates in nGyh?1 or ?Gyh?1. A simple calibration of NaI(Tl), HPGe as well as plastic detectors for the low-level air kerma rates is presented in this contribution. This calibration is based on comparing the relative absorbed energy rate in detectors (MeVs?1) calculated from spectra with the air kerma rates calculated by the Monte Carlo simulation and supplementary to the data from the RSS Reuter&Stokes high pressure ion chamber. This method also eliminates the conversion from the non-air kerma rates in crystals to the air kerma rates. Three different types of small cylindrical detectors were calibrated for the air kerma rates from the background of 26 nGyh?1 to some tens of ?Gyh?1 in the energy range to the maximum of 3 MeV. The results of calibrations of the 3" x 3" NaI(Tl), HPGe detector and a small plastic detector (made of polystyrene) including soxme examples of environmental measurements are presented.

Evaluation of High-Purity Synthetic Silica Vials in Active and Passive Vial Holders for Liquid Scintillation Counting of Benzene

We evaluate high-purity synthetic silica vials in both delrin and active plastic holders (Pico adapters™) for 14C dating, using liquid scintillation counting of benzene. We have designed synthetic silica vials in the form of simple cylinder-cells based on the standard 7-ml vial. We have also designed a delrin holder for supporting 7-ml silica or glass vials. We compare the counting efficiency and background of the silica vials with Teflon, plastic and low-K glass vials for both delrin holders and Pico adapters in the 1220 Quantulus and Packard Tri-Carb 2660 XL, fitted with a plastic detector guard. In the 1220 Quantulus, synthetic silica vials in Pico adapters have the highest figure of merit (FM), closely followed by silica in delrin holders and Teflon. In the Packard Tri-Carb 2660 XL, plastic vials in Pico adapters give the highest FM.