ABSTRACT
A 4πγ integral counting system with a NaI(Tl) well-type detector and a digital interface to acquire measurement data was implemented at LMR-CNEA. The detection efficiency as a function of the energy was computed by Monte Carlo simulations and the total efficiencies for ampoules and point sources were calculated considering all the decay branches. A computer code was developed to analyse data. This program reads the files generated by the digitizer module, corrects for dead time and calculates source activities and their uncertainties. Ampoules with solutions of 113Sn, 192Ir and 131I were measured.
ABSTRACT
The nuclide (241)Am decays by alpha emission to (237)Np. Most of the decays (84.6%) populate the excited level of (237)Np with energy of 59.54 keV. Digital coincidence counting was applied to standardize a solution of (241)Am by alpha-gamma coincidence counting with efficiency extrapolation. Electronic discrimination was implemented with a pressurized proportional counter and the results were compared with two other independent techniques: Liquid scintillation counting using the logical sum of double coincidences in a TDCR array and defined solid angle counting taking into account activity inhomogeneity in the active deposit. The results show consistency between the three methods within a limit of a 0.3%. An ampoule of this solution will be sent to the International Reference System (SIR) during 2009. Uncertainties were analysed and compared in detail for the three applied methods.
Subject(s)
Americium/standards , Radiometry/methods , Alpha Particles , International Cooperation , Reference Standards , Reproducibility of Results , Scintillation Counting/methods , UncertaintyABSTRACT
A non-radionuclide-specific computer code to analyze data, calculate detection efficiency and activity in a TDCR system is presented. The program was developed prioritizing flexibility in measuring conditions, parameters and calculation models. It is also intended to be well structured in order to easily replace subroutines which could eventually be improved by the user. It is written in standard FORTRAN language but a graphical interface is also available. Several tests were performed to check the ability of the code to deal with different decay schemes such as H-3, C-14, Fe-55, Mn-54 and Co-60.
