Performance evaluation of radon monitors at IFIN-HH, Romania.

Starting in 2022, the calibration of various radon monitors received from customers was performed for the first time in Romania by LMRI at IFIN-HH, designated by CNCAN as a calibration laboratory. The purpose of the study was to analyze the radon monitors responses and their uncertainties, and finally compare their performance with the standard radon monitor AlphaGuard in order to improve the calibration process in the future. Measurement results and the uncertainty budgets are presented in the paper.

The Metrological Traceability, Performance and Precision of European Radon Calibration Facilities.

An interlaboratory comparison for European radon calibration facilities was conducted to evaluate the establishment of a harmonized quality level for the activity concentration of radon in air and to demonstrate the performance of the facilities when calibrating measurement instruments for radon. Fifteen calibration facilities from 13 different European countries participated. They represented different levels in the metrological hierarchy: national metrology institutes and designated institutes, national authorities for radiation protection and participants from universities. The interlaboratory comparison was conducted by the German Federal Office for Radiation Protection (BfS) and took place from 2018 to 2020. Participants were requested to measure radon in atmospheres of their own facilities according to their own procedures and requirements for metrological traceability. A measurement device with suitable properties was used to determine the comparison values. The results of the comparison showed that the radon activity concentrations that were determined by European calibration facilities complying with metrological traceability requirements were consistent with each other and had common mean values. The deviations from these values were normally distributed. The range of variation of the common mean value was a measure of the degree of agreement between the participants. For exposures above 1000 Bq/m3, the variation was about 4% for a level of confidence of approximately 95% (k=2). For lower exposure levels, the variation increased to about 6%.

60 years of absolute standardization of radionuclides by coincidence counting methods in the Romanian metrology laboratory.

This review paper presents the contribution of the Radionuclide Metrology Laboratory (RML) to the development and practical application of the coincidence counting methods. It is also intended to pay tribute to Dr. Enric Leon Grigorescu, the founder of our school of radionuclide metrology. A synthetic treatment of the method, applied to some classes of radionuclides with their common and particular aspects in standardization, is presented: pioneering calculation of instrumental corrections, specific method corrections applied for various types of decay schemes in the variant of efficiency extrapolation, results obtained in international comparisons.

Absolute standardization of 57Co and analysis of the results obtained in two international comparisons.

The absolute standardization of Co-57 by the 4π(PC)-γ coincidence method, in efficiency extrapolation variant, is presented. An original, improved method, based on the use of the equivalent decay scheme, was applied; apart from the enhancement of efficiency, a diminution of extrapolation slope was obtained, lowering the extrapolation uncertainty. The results obtained in the participation at the supplementary comparison CCRI(II)-S6.Co-57 and at the key comparison code BIPM.RI(II)-K1.Co-57 are presented. The method allows to simplify the treatment of 56Co and 58Co impurities' correction, which influences significantly the measurements in a CENTRONIC type ionization chamber. An example of treatment of this mixture, where the influence of impurities on results was analyzed, will be presented.

Results of the CCRI(II)-S12.H-3 supplementary comparison: Comparison of methods for the calculation of the activity and standard uncertainty of a tritiated-water source measured using the LSC-TDCR method.

A comparison of calculations of the activity of a 3H2O liquid scintillation source using the same experimental data set collected at the LNE-LNHB with a triple-to-double coincidence ratio (TDCR) counter was completed. A total of 17 laboratories calculated the activity and standard uncertainty of the LS source using the files with experimental data provided by the LNE-LNHB. The results as well as relevant information on the computation techniques are presented and analysed in this paper. All results are compatible, even if there is a significant dispersion between the reported uncertainties. An output of this comparison is the estimation of the dispersion of TDCR measurement results when measurement conditions are well defined.

Experimental determination of some nuclear decay data in the decays of (177)Lu, (186)Re and (124)I.

A detailed experimental study of the radionuclides (177)Lu, (186)Re and (124)I was conducted at IFIN-HH, Radionuclide Metrology Laboratory. Absolute photon emission intensities in the decays of these radionuclides were measured by high-resolution gamma-ray spectrometry. Half-life measurements using a well-type ionization chamber were also performed. These new experimental results will be useful for the future updates of the existing nuclear decay data evaluations, offering reliable and accurate data for the users.

Construction and implementation of a TDCR system at ENEA.

A new 4π (LS) TDCR system was built at ENEA-INMRI. Three photomultiplier tubes, arranged in a planar 120° geometry around a spherical optical chamber, were directly linked to a CAEN Desktop Digitizer DT5720. This module, based on the Field Programmable Gate Array (FPGA) technology for real time Digital Pulse Processing (DPP), allowed to replace all the classical TDCR electronics by only one device. The activity of (3)H and (63)Ni standard sources were successfully measured by the new detector.

Measurements of 64Cu and 68Ga half-lives and γ-ray emission intensities.

The (64)Cu and (68)Ga half-lives and γ-ray intensities were measured at IFIN-HH. The determination of absolute photon emission intensities was based on absolute activity standardizations carried out in this laboratory using the 4πPC-γ coincidence method. The half-lives were measured with a well-type ionization chamber. The photon emission intensities (relative and absolute values) were measured with a calibrated high-resolution γ-ray spectrometer. The results obtained and their uncertainties are discussed and compared with values of other authors.

Participation in the CCRI(II)-K2.H-3 comparison and study of the new TDCR-LS counter with 6 CPMs.

The "conventional" TDCR system was used for standardization of the tritiated water in the frame of the international comparison organized by CCRI(II). The prototype of the new TDCR realized at LNHB with three CPMs (Ivan et al., 2008) was improved by constructing at IFIN-HH, a system containing six channel photomultiplier tubes arranged symmetrically in a new optical chamber. The system was tested by measuring various pure beta emitters and for comparative measurements of tritiated water for validation studies.