The absence of a certified standard for radon-in-water presents a significant gap in environmental monitoring and water production quality control in compliance with EURATOM directive 2013/51. To address this, we developed a system to produce a radon-in-water primary standard derived from the radon primary standard available at LNHB, which is based on counting in defined solid angle (DSA). The radon certified by DSA counting was dissolved into a known quantity of water using a newly developed system that allows a loss-free transfer with ensured accuracy and reproducibility. To validate the production of this standard, multiple primary measurement methods were employed. Radon activity in water was determined using liquid scintillation counting, specifically the triple-to-double coincidence ratio method, which provides a direct and highly accurate measurement. Additionally, gamma-ray spectrometry (GS) was applied as an independent verification technique. Comparative analysis of these methods was conducted to assess their consistency and reliability in certifying the radon-in-water standard. The results demonstrated the effectiveness of our production method and confirmed the validity of the radon-in-water standard. However, our study also revealed subtle yet significant factors influencing GS measurements, highlighting the need for careful consideration of such effects in future measurements. This work contributes to the establishment of a robust and reliable radon-in-water standard, addressing a critical need in the field and supporting improved traceability chain, environmental monitoring, radioprotection, and calibration of measurement systems.

I-123 (T1/2 = 13.2234(37) h) decays by electron capture mainly via the 159 keV level of Te-123 (97 %) and is characterized by strong gamma-ray emission at 159.0 keV, as well as intense tellurium K X-rays and numerous low-intensity gamma-rays with energies up to 1 MeV. Lu-177 (T1/2 = 6.647(4) d) decays by beta-emission to the ground state and to three excited levels of Hf-177. Its main photon emissions are the hafnium K X-rays and gamma-rays at 112.9 keV and 208.4 keV; four minor gamma-rays are also emitted. The measurement of photon emission intensities was performed using four N-type high-purity germanium detectors accurately calibrated using standard point sources, in complementary energy ranges. For each radionuclide, several point sources were prepared and checked for homogeneity. For 123I, the study was carried out in two stages. Here, only relative photon emission intensities for about 30 energies could be measured, with relative combined standard uncertainties of about 1 % for the largest ones and of about 2 %-2.5 % for ten minor lines. For 177Lu, the sources were measured in the calibration conditions (at the reference distance) to derive absolute photon emission intensities, thanks to accurate sources activity, obtained by a primary method (4π β-γ coincidences using a liquid scintillation detector in the β channel). The six absolute gamma-ray emission intensities are obtained with relative combined standard uncertainties between 0.7 % and 1.9 %. The whole measurement procedure is presented and the resulting photon emission intensities are compared with previously published values.

An accurate database of atomic fundamental parameters (FPs) is crucial for quantitative material analysis based on x-ray fluorescence (XRF). Given the wide range of applications and the limited reliability of existing experimental FPs for the L subshells of platinum, we determined its partial L fluorescence yields and Coster-Kronig transition probabilities using transmission and reference-free XRF measurements. The determined values are omega L3 = 0.289 (11), omega L2 = 0.326 (13), omega L1 = 0.0820 (34), f 23 = 0.130 (39), f 12 = 0.158 (40), and f 13 = 0.37 (18). These results show good agreement with certain tabulated values, and systematic trends are observed across atomic number Z for omega L3, omega L2, f 12, and f 13. The relative standard uncertainties for omega L2, omega L1, and f 12 have been significantly reduced compared to previous experimental studies. The use of tunable monochromatic photon beams and high-precision instrumentation allowed us to establish a reliable uncertainty budget for the determined results.

Reliable X-ray emission intensities are essential for quantitative material analysis using X-ray spectrometry and for the efficiency calibration of energy-dispersive spectrometers. In order to improve the reliability of data, reference-free measurements were performed to determine X-ray emission intensities, along with their associated uncertainties, for a set of standard radionuclides in the energy range from 5.4 keV to 53.13 keV. Partial K X-ray emission intensities were determined for nine radionuclides, resulting in total K emission intensities, IXK, of 24.06(49)% for 54Mn, 27.59(48)% for 55Fe, 55.8(10)% for 57Co, 37.4(9)% for 65Zn, 60.0(7)% for 85Sr, 59.0(7)% for 88Y, 100.5(15)% for 109Cd, 117.3(12)% for 133Ba and 77.7(9)% for 139Ce. In addition, γ-ray emission intensities were measured as 8.77(12)% for the 14.41 keV transition of 57Co and 2.199(29)% for the 53.16 keV transition of 133Ba. The results are in good agreement with existing data, although some differences were observed for a few radionuclides. For all investigated radionuclides, a fully traceable and reliable uncertainty budget has been provided.

Accurate neutron flux characterization across different energy regions is crucial in reactor dosimetry and is typically achieved by measuring the activity of irradiated dosimeters. For niobium dosimeters, the limited reliability of K X-ray emission intensities in the decay of 93mNb remains a key challenge. To address this, we carried out a dedicated experiment. Liquid scintillation counting using the triple-to-double coincidences ratio method was conducted to determine the reference activity, which is then combined with X-ray spectrometry, performed using a high-purity germanium detector with a reference-free efficiency calibration, to determine the K X-ray emission intensities. The obtained results are 9.19(12)%, 1.557(28)% and 0.256(18)% for the Kα, K'β1 and K'β2 intensities, respectively, resulting in a total K emission intensity (IXK) of 11.00(12)%. These results show good agreement with certain literature values. The relative standard uncertainties for the Kα, Kβ and IXK intensities have been reduced to 1.3 %, 1.8 % and 1.1 %, respectively, compared to existing values, providing a reliable and fully traceable uncertainty budget for the obtained results.

ACORES is a software developed by the Laboratoire National Henri Becquerel (LNHB) for the efficiency calibration of semi-conductor detectors. It calculates the efficiency curve from the measurements and analysis of full-energy peaks (position and net area). The adjustment is performed using polynomial functions of the logarithm of the energy or its inverse. ACORES takes into account correlations between input data via the relative uncertainty on the activity associated to each radionuclide.

A cryogenic electrical-substitution radiometer was used for the primary calibration of monochromatic photon beams at synchrotron, which are in turn employed to determine the intrinsic efficiency of an HPGe detector between 3.5 keV and 8 keV. This allowed the determination of the thickness of the dead layer, which enabled the calculation of the efficiency up to 55 keV, where the active thickness is not determinant. The geometrical efficiency was determined through the measurement of a radioactive source at variable distances.

CEA/Cadarache operates the MADERE facility dedicated to measuring the activity of radionuclides generated during the irradiation of specific dosimeters made of hyper-pure materials. This facility is equipped with seven spectrometers, two of which are dedicated to the detection of radionuclides that emit X-rays. The laboratory that operates the MADERE facility processes solid-state rhodium and niobium dosimeters, which emit X-rays of 20 keV and 16 keV respectively. In recent years, there have been significant improvements in nuclear decay data, leading to better measurement of these two X-ray emitters. A joint LDCI and LNHB thesis, defended in 2018, produced major advances (for example self-attenuation corrections for 93mNb and 103mRh). The most significant achievements and outlooks are presented in this paper for the both niobium and rhodium dosimeters.

The precise characterization of thin layers in microelectronics or related fields is more and more challenging as the targeted thicknesses are decreasing into the nanometer range. Combined XRR-GIXRF analysis is a powerful technique that combines the advantages of the elemental sensitivity of X-ray fluorescence with the thickness and density sensitivity of X-ray reflectivity. This method is performed in a reference-free mode which relies on the precise knowledge of some physical quantities.

In the field of quantitative X-ray analysis techniques, such as electron probe microanalysis, precise knowledge of fundamental parameters is crucial. Especially, the accurate determination of photon mass attenuation coefficients is essential to perform correct elemental quantification. While the widely used databases offer agreement for the hard X-ray range, significant differences arise for lower photon energies. Furthermore, addressing the uncertainties of the tabulated data, which can be of several hundreds of percent, is of urgent need. Driven by recent advances in analytical techniques in the low energy range including investigation of materials containing lithium, the interest in a reliable set of photon mass attenuation coefficients is steadily increasing. In this study, we experimentally determine photon mass attenuation coefficients for lithium fluoride, aluminium, and different transition metals in the extreme low energy range from 40 eV to a several hundreds of eV. This high-precision experimental determination allows a comparison with the existing data tables. We observe differences that turn out to be significant, especially around the absorption edges.

Niobium is a dosimeter used to characterize fast-neutron reaction rates to monitor nuclear reactor vessels. Its characterization is based on the activity of 93mNb resulting from the 93Nb(n,n’) activation reaction. The decay of 93mNb results mainly in the emission of niobium K X-rays which are used to determine the activity of 93mNb. Direct measurement using X-ray spectrometry does not require any sample preparation, but fluorescence effects, due to impurities which are activated during irradiation, must be taken into account. Indeed, some of these radioactive impurities, in particular 182Ta, and other niobium isotopes remain present during the measurements and disturb the X-ray spectra. The fluorescence effect induces additional niobium X-ray emission to that due to the 93mNb decay alone, which leads to an overestimation of the dosimeter activity, especially if the results are expected shortly after the end of the irradiation. It is therefore necessary to assess the contribution of fluorescence effects to provide accurate values of 93mNb activity. Fluorescence correction factors were established by Monte Carlo simulation. The calculated fluorescence correction factors were validated by an experimental approach, using activated niobium dosimeters with different tantalum concentrations.

The Ta/Cr/Pt three-layer system can be used as a planar x-ray waveguide, that is to say it can guide an x-ray beam inside its chromium layer. This property comes from the difference in density and hence in optical index between the two "heavy" or cladding tantalum and platinum layers and the "light" or guiding chromium layer. The waveguide will be efficient provided the layers are a few nanometers thick and that the interfaces are as sharp as possible. To control the quality of the stack, we combine grazing incidence x-ray fluorescence (GIXRF) and x-ray reflectivity (XRR) measurements on a series of Ta/Cr/Pt samples, whose only difference is the thickness of the Cr layer. The three considered samples have been deposited by magnetron sputtering and their designed structures are: Ta (8 nm)/Cr (5, 10, and 15 nm)/Pt (14 nm)/Si substrate. The combination of XRR and GIXRF tightens constraints on the parameters used to simulate the stack: thickness, roughness, composition, and density of the layers and their interlayers. For each sample we used six GIXRF curves obtained from three different characteristic x-ray lines (Ta L & alpha;, Cr K & alpha;, and Pt L & beta;(2,15)) excited at three different incident photons energies (6.25, 10, and 12 keV) as well as one XRR curve obtained at 6.25 keV. The XRR-GIXRF combined analysis demonstrates that the Ta/Cr/Pt structure is too simplistic and that it is necessary to introduce some interlayers at the top and bottom of the stacks to obtain a reliable agreement between the experimental and simulated GIXRF and XRR curves.

This work presents a new system dedicated to the measurement of energy spectra from radionuclide-based neutrons sources (ex. AmBe, PuBe, 252 Cf). The experimental device consists of a large-volume polyethylene container that is equipped with a central channel accommodating the source to be measured and 12-measurement channels (in a spiral formation) around the source, into which detectors can be placed. The container is filled with water in order to moderate neutrons emitted from the source and to reduce the sensitivity of the detectors to the external environment. Measurements have been performed with 6 Li-doped plastic scintillators (PS) developed in-house and optimized for the simultaneous detection of fast neutrons, thermal neutrons, and gamma rays, through signal processing based on Pulse Shape Discrimination (PSD). This novel approach solves the underdetermined problem as observed in the case of classical neutron spectrometers (ex. Bonner sphere systems with limited experimental data). Through the use of 6 Li-doped PS information, the increased experimental data enable the spectrum of interest to be recreated without the need to introduce a "default spectrum" in the unfolding process. The reconstruction is performed with an iterative Maximum-Likelihood Expectation–Maximization algorithm (ML-EM) throughout the detector's responses matrix calculated with the MCNP6 code. An optimized version of this ML-EM algorithm with a regularization step has been also tested. The design, methodology and preliminary results are presented. Different types of neutron sources were measured and results are consistent, with a clear benefit when using experimental data taking into account the measured fast neutron component instead of using only thermal neutron counting.

The combination of X-ray reflectivity (XRR) and grazing incidence X-ray fluorescence (GIXRF) is a surface sensitive analytical method, which can be used for the characterization of thin films and multilayered materials. Both of these techniques are implemented on the same experimental setup and make use of similar mechanical processes and the same fundamental physical concept required for a combined data analysis. The combination of these techniques removes ambiguous results for the characterization of nanometer layers, as well as nanometer depth profiles, resulting in more accurate characterization of thickness, roughness, density, and elemental composition. Due to the vast number of fitting parameters, the estimation of the thin film sample structure is a challenging task. In this paper, we propose a recursive method for estimating the uncertainties of data from GIXRF-XRR analysis, based on a Bootstrap statistical method. This approach relies on re-sampling a dataset to estimate statistics on a population by applying random weights. We applied this method on an as-deposited chalcogenide germanium, antimony, and tellurium (GST) thin film with a carbon-capping layer. We found good agreement between the experimental and the theoretical XRR-GIXRF values for a sample structure model, of which the parameters were determined within a confidence interval using the bootstrap method. We also propose an approach for calculating the uncertainty on the solid angle of detection based on Monte Carlo simulations.

Following an initial Round Robin inter-comparison of gamma spectrometry measurements reported in 2014, this paper presents results from the first part of a second Round Robin inter-comparison commissioned by the European Working Group on Reactor Dosimetry in 2018. Measurements were performed by thirteen European organisations on a set of irradiated neutron activation detectors representative of those commonly used by the Reactor Dosimetry community to measure neutron fluence using gamma spectrometry methods. The radionuclides measured were110mAg,58Co,60Co,54Mn, and46Sc. The purpose of the exercise was to demonstrate the level of consistency between participating organisations in blind tests of measurements. The samples used were disks of iron, nickel, titanium, and two standard alloys of aluminium, one of 1% cobalt and the other 1% silver. They were irradiated in the MARIA reactor operated by National Centre for Nuclear Research, Poland. Participants provided their results to an independent referee who collated and compared the data. The results are presented in an anonymised form together with discussion and conclusions which may be drawn from the exercise. Good agreement was obtained with standard deviations for individual measurements between 2.0% (54Mn) and 5.6% (60Co). Overall, the results obtained from the latter Round Robin show less consistency than those from the first Round Robin, which is attributed to the participation of a wider pool of organisations.

The electrical-substitution cryogenic detector BOLometer for Use in the range of X-rays (BOLUX), which was developed some years ago at CEA/DAM, has been set up and restarted now at LNHB. It has been used for the primary measurement of the intensity (total energy per unit time) of monochromatic synchrotron beams in the energy range from 3 to 30 keV. These well-determined photon beams have been employed for the efficiency calibration of two photodiodes in terms of current induced per unit optical power at different photon energies. In a final step, we explored the possibility to use these primary-calibrated photodiodes to determine the efficiency curve of an energy-dispersive spectrometer based on a semiconductor detector (Silicon Drift Detector) using less intense monochromatic photon fluxes. The characteristics of the radiometer BOLUX and its principle of operation are described, and the measurements carried out at the synchrotron beamline are presented, including the determination of the beams' intensities, the direct calibration of photodiodes with respect to BOLUX and the use of one of those photodiodes as a standard transfer for the calibration of the SDD.

The goal of this study is to provide a benchmark for the use of Monte Carlo simulation when applied to coincidence summing corrections. The examples are based on simple geometries: two types of germanium detectors and four kinds of sources, to mimic eight typical measurement conditions. The coincidence corrective factors are computed for four radionuclides. The exercise input files and calculation results with practical recommendations are made available for new users on a dedicated webpage.

Despite widespread radon-in-water measurements, no primary radon-in-water standards currently exist. This work aims to bridge this gap by developing a system to produce radon-in-water reference materials. The system relies on cryogenic, loss-free transfer of radon, which is standardized through defined solid angle measurements, to a radon standard in water. It allows for preparation of liquid scintillation and gamma-ray spectrometry samples with traceable radon-in-water concentrations. The system's design, functionality, and the results of pilot performance tests are described.

Following on from an initial Round Robin inter-comparison of gamma spectrometry measurements reported in 2014, this paper presents the results of the second part of a further Round Robin inter-comparison commissioned in 2018 by the European Working Group on Reactor Dosimetry. The purpose of the exercise was to demonstrate the level of consistency between different organisations’ measurements of the 93Nb(n,n’)93mNb reaction, which plays a key role in underwriting reactor dosimetry assessments. To achieve this, measurements of 93mNb activity were performed by twelve European organisations on six sets of near identical niobium samples, each having its own geometry and tantalum concentration. The samples were provided by CEA, France and irradiated in the MARIA reactor, operated by National Centre for Nuclear Research, Poland. Participants provided their results to an independent referee who collated and compared the data. The inter-comparison has demonstrated agreement to within standard deviations ranging from ±2.2% to ±7.9%, with a tendency for some organisations to measure elevated values. The results of the inter-comparison are presented in an anonymised form together with discussion and conclusions which may be drawn from the exercise.