An approach based on the SIR measurement model for determining the ionization chamber efficiency curves, and a study of 65Zn and 201Tl photon emission intensities.

The measurement model used to determine ionization chamber efficiency curves accounts from the outset for impurity corrections and beta spectrum shapes. The curves are represented by exponentials of polynomials whose coefficients are adjusted using non-linear least-squares minimization. The curves are validated by comparing with SIR key comparison reference values (KCRVs) and other published curves. The associated covariance matrix is also evaluated. Deviations from model predictions for 65Zn and 201Tl using recommended nuclear data are studied.

[1]  A. Lorenz.  X-ray and gamma-ray standards for detector calibration , 1994 .

[2]  D. Wilkinson.  Evaluation of beta-decay: II. Finite mass and size effects☆ , 1990 .

[3]  D. Wilkinson.  Evaluation of beta-decay, Part VI: The Z-dependent outer radiative corrections for allowed decay , 1997 .

[4]  A. Rytz,et al.  The international reference system for activity measurements of γ-ray emitting nuclides , 1983 .

[5]  A. Švec,et al.  Fitting methods for constructing energy-dependent efficiency curves and their application to ionization chamber measurements. , 2002, Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine.

[6]  A. Rytz.  International coherence of activity measurements , 1978 .

[7]  H. Janssen,et al.  Evaluation of atomic shell data , 1996 .

[8]  A. Švec,et al.  Comparison of ionization chamber efficiencies for activity measurements. , 2004, Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine.

[9]  M. Bé.  Activity measurements and determination of gamma-ray emission intensities in the decay of 65Zn. , 2006, Applied Radiation and Isotopes.

[10]  D. Wilkinson.  Evaluation of beta-decay, Part VII: The Z-independent outer radiative correction for unique-forbidden decay , 1998 .

[11]  Schrader.  Calibration and consistency of results of an ionization-chamber secondary standard measuring system for activity , 2000, Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine.

[12]  Michotte.  Influence of radioactive impurities on SIR measurements , 2000, Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine.

[13]  D. Wilkinson.  Evaluation of beta-decay: I. The traditional phase space factors , 1989 .

[14]  B.R.S. Simpson,et al.  Portability of the calibration of SIR of BIPM to other ionization chambers for radioactivity measurements , 1998 .

[15]  G. Ratel,et al.  BIPM comparison BIPM.RI(II)-K1.Zn-65 of activity measurements of the radionuclide 65Zn for the BARC (India) with linked results for the CCRI(II)-K2.Zn-65 comparison , 2004 .