Activity measurements and gamma emission intensities determination in the decay of 65Zn
Project Description
Results of Sb-124 activity measurements sent to the SIR are scarce. Only three laboratories contributed, two of them using the coincidence counting technique (they are in agreement) and the third one by the mean of a 4?? counter. The LNHB result differs from the two others by 2%.
Recently, LNE-LNHB carried out a specific exercise for the standardization of a Sb-124 solution using different measurements techniques and taking into account possible impurities. Such differences between the different techniques were also observed. [C Michotte et al 2006 Metrologia 43 06007 ]. It must be pointed out that the LNE-LNHB result coming from the coincidence counting technique is in good agreement with the two values showed in the SIR and that there is no other available measurement result obtained by another technique which could be compared with the 4???result.
Hence the first part of this exercise will be dedicated to activity measurements, participants will be asked to do all techniques they could use.
From the exercise quoted above, problem in the decay scheme cannot be excluded and, moreover this nuclide having high energy gamma rays, it could be valuable for detector calibration. So, this exercise can also be the opportunity to improve the uncertainties on the gamma ray intensities. Participants will be asked to carry out gamma ray measurement too.
The participants would send their data to LNE-LNHB which will summarize the main elements and will do a decay data evaluation.
LNE-LNHB proposes to provide NMIs with Sb-124 ampoules solution, if required.
The Technical Report can be downloaded here>>
Final Report 2009-08-25
The international traceability of antimony 124, in terms of activity, was very limited. The results of 124Sb activity measurements sent to the SIR (BIPM – International System of Reference, BIPM.RI(II)-K1.Sb-124.) were scarce (only three laboratories) with some discrepancies observed according to the methods used. In other respects, this nuclide emits high-energy gamma rays, and then could be selected as a valuable standard radionuclide for the calibration of gamma-ray detectors in that energy range, given well known photon intensities.
The first part of this exercise was dedicated to activity measurements and to their comparison. For this purpose, participants were asked to make use of all the direct measurement techniques available in their laboratory in order to confirm or not the existence of possible biases specific to some measuring methods.
In addition, this exercise offered the opportunity of improving the uncertainties of the gamma-ray intensities. Then, participants were asked, in the second part, to carry out X-ray and gamma-ray intensity measurements. These results have been compared to previous published values and new decay scheme data are proposed.
The final report was written and registered as CEA Report 6222. A paper is in preparation to be presented at the ICRM Conference 2009 (Bratislava) and published in Applied Radiation Isotopes.