Comparison of the standards for air kerma of the ITN (Portugal) and the BIPM for⁶⁰Co γ-rays

Abstract

A first comparison of the standards for air kerma of the Instituto Tecnológico e Nuclear (ITN), Portugal and of the Bureau International des Poids et Mesures (BIPM) has been carried out in 60Co radiation under the auspices of the key comparison BIPM.RI(I)-K1. The comparison result, expressed as a ratio of the ITN standard and the BIPM standard, is 1.0015 (0.0018). The degrees of equivalence between the ITN and the other participants in the key comparison have been calculated and the results are presented in the form of a matrix. A graphical presentation is also given.Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCRI Section I, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Comparisons of the standards for air kerma of the GUM and the BIPM for60Co and137Cs gamma radiation

“…The values of the physical data used in (1) are consistent with the CCEMRI(I) 1985 recommendations [4]. These values and those for the various corrections needed for 60 Co and 137 Cs radiation are also shown in Tables 2 and 3, respectively, for both the GUM and the BIPM standards, together with their associated uncertainties.…”

“…Table 3. Physical constants and correction factors with their estimated relative uncertainties of the BIPM and GUM standards for the 137 Cs gamma radiation beam at the BIPM BIPM standard GUM standard values uncertainty (1) values uncertainty (1)…”

“…Direct comparisons of the standards for air kerma in 60 Co and 137 Cs gamma radiation of the Główny Urząd Miar (GUM), Poland and the Bureau International des Poids et Mesures (BIPM) were carried out in April 2006 in the BIPM 60 Co and 137 Cs radiation beams. The last direct comparison of the air kerma standards for 60 Co gamma radiation was in 1996 [1]. No previous comparison has been made for 137 Cs air kerma although some measurements were made with the primary standard in the BIPM 137 Cs beam in 1996.…”

Comparison of the standards for air kerma of the BEV and the BIPM for137Cs gamma radiation

“…Note that although the black squares indicate results that date prior to 1999, the BEV, VSL and the NRC have made comparisons more recently. The results of a recently published SIM comparison [13] and for the 2005 comparison with the ITN (Portugal) [14] are also presented.…”

Comparison of the standards for air kerma of the VSL and the BIPM for60Co gamma radiation

“…The NRC (Canada), PTB (Germany) and the BEV (Austria) have already declared new values for their air kerma standards [20,21,22]. The SZMDM (Serbia and Montenegro), the NCM (Bulgaria), ENEA (Italy) and the ITN (Portugal), all of which have made comparisons recently with the BIPM [23,24,25,26], have also changed their previous method of k wall determination, now using Monte Carlo calculations. The NMi (Netherlands) has re-evaluated their corrections [27] and is in the process of declaring their new standard value.…”