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Pommé S, Veale MC, Pooley DE, Van Assche F, Falksohn F, Collins SM. Analysis of a neutron-induced conversion electron spectrum of gadolinium. Appl Radiat Isot 2023; 197:110828. [PMID: 37126950 DOI: 10.1016/j.apradiso.2023.110828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 03/25/2023] [Accepted: 04/17/2023] [Indexed: 05/03/2023]
Abstract
A 100-nm-thick gadolinium layer deposited on a pixelated silicon sensor was activated in a neutron field to measure the internal conversion electron (ICE) spectrum generated by neutron capture products of 155Gd and 157Gd. The experiment was performed at the ISIS neutron and muon facility, using a bespoke version of the HEXITEC spectroscopic imaging camera. Signals originating from internal conversion electrons, Auger electrons, x rays and gamma rays up to 150 keV were identified. The ICE spectrum has an energy resolution of 1.8-1.9 keV at 72 keV and shows peaks from the K, L, M, N+ ICEs of the 79.51 keV and 88.967 keV 2+-0+ gamma transitions from the first excited states in 158Gd and 156Gd, respectively, as well as the K ICEs of the 4+-2+ transitions at 181.931 keV and 199.213 keV from the respective second excited states. Spectrum analysis was performed using a convolution of a Gaussian with exponential functions at the low and high energy side as the peak shaping function. Relative ICE intensities were derived from the fitted peak areas and compared with internal conversion coefficient (ICC) values calculated from the BrIcc database. Relative to the dominant L shell contribution, the K ICE intensity conforms to BrIcc and the M, N, O+ ICE intensities are somewhat higher than expected.
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Affiliation(s)
- S Pommé
- European Commission, Joint Research Centre (JRC), Geel, Belgium.
| | - M C Veale
- Technology Department, Rutherford Appleton Laboratory (STFC), Oxfordshire, UK
| | - D E Pooley
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory (STFC), Oxfordshire, UK
| | | | - F Falksohn
- National Physical Laboratory (NPL), Teddington, UK
| | - S M Collins
- National Physical Laboratory (NPL), Teddington, UK; School of Mathematics and Physics, University of Surrey, Guilford, UK
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Röttger S, Röttger A, Mertes F, Morosch V, Ballé T, Chambers S. Evolution of traceable radon emanation sources from MBq to few Bq. Appl Radiat Isot 2023; 196:110726. [PMID: 36898321 DOI: 10.1016/j.apradiso.2023.110726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 01/19/2023] [Accepted: 02/14/2023] [Indexed: 02/26/2023]
Abstract
In the framework of the EMPIR project traceRadon, stable atmospheres with low-level radon activity concentrations have to be produced for calibrating radon detectors designed to measure outdoor air activity concentrations. The traceable calibration of these detectors at very low activity concentrations is of special interest to the radiation protection, climate observation, and atmospheric research communities. Radiation protection networks (such as the EUropean Radiological Data Exchange Platform (EURDEP)) and atmospheric monitoring networks (such as the Integrated Carbon Observation System (ICOS)) need reliable and accurate radon activity concentration measurements for a variety of reasons, including: the identification of Radon Priority Areas (RPA); improving the sensitivity and reliability of radiological emergency early warning systems (Melintescu et al., 2018); for more reliable application of the Radon Tracer Method (RTM) to estimate greenhouse gas (GHG) emissions; for improved global "baseline" monitoring of changing GHG concentrations and quantification of regional pollution transport (Chambers et al., 2016), (Chambers et al., 2018); and for evaluating mixing and transport parameterisations in regional or global chemical transport models (CTMs) (Zhang et al., 2021), (Chambers et al., 2019). To achieve this goal, low activity sources of radium with a variety of characteristics were produced using different methods. Sources ranging from MBq 226Ra down to several Bq 226Ra were developed and characterised during the evolution of production methods, and uncertainties below 2 % (k= 1) were achieved through dedicated detection techniques, even for the lowest activity sources. The uncertainty of the lowest activity sources was improved using a new online measurement technique for which the source and detector were combined in the same device. This Integrated Radon Source Detector device, henceforth an IRSD, reaches a counting efficiency approaching 50 % through detection under quasi 2π sr solid-angle. At the time of this study the IRSD was already produced with 226Ra activities between 2 Bq and 440 Bq. To compare the working performance of the developed sources (i.e., to establish a reference atmosphere), study the stability of the sources, and to establish traceability to national standards, an intercomparison exercise was carried out at the PTB facility. Here we present the various source production techniques, the determination of their radium activity, and determination of their radon emanation (including assigned uncertainties). This includes details of the implementation of the intercomparison set-up, and a discussion of the results of the source characterisations.
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Affiliation(s)
- Stefan Röttger
- Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116, Braunschweig, Germany.
| | - Annette Röttger
- Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116, Braunschweig, Germany
| | - Florian Mertes
- Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116, Braunschweig, Germany
| | - Viacheslav Morosch
- Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116, Braunschweig, Germany
| | - Tanita Ballé
- Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116, Braunschweig, Germany
| | - Scott Chambers
- Australian Nuclear Science and Technology Organisation (ANSTO), New Illawarra Road, Lucas Heights, NSW, 2234, Australia
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Abstract
AbstractRadionuclides, whether naturally occurring or artificially produced, are readily detected through their particle and photon emissions following nuclear decay. Radioanalytical techniques use the radiation as a looking glass into the composition of materials, thus providing valuable information to various scientific disciplines. Absolute quantification of the measurand often relies on accurate knowledge of nuclear decay data and detector calibrations traceable to the SI units. Behind the scenes of the radioanalytical world, there is a small community of radionuclide metrologists who provide the vital tools to convert detection rates into activity values. They perform highly accurate primary standardisations of activity to establish the SI-derived unit becquerel for the most relevant radionuclides, and demonstrate international equivalence of their standards through key comparisons. The trustworthiness of their metrological work crucially depends on painstaking scrutiny of their methods and the elaboration of comprehensive uncertainty budgets. Through meticulous methodology, rigorous data analysis, performance of reference measurements, technological innovation, education and training, and organisation of proficiency tests, they help the user community to achieve confidence in measurements for policy support, science, and trade. The author dedicates the George Hevesy Medal Award 2020 to the current and previous generations of radionuclide metrologists who have devoted their professional lives to this noble endeavour.
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Mertes F, Röttger S, Röttger A. Development of 222Rn Emanation Sources with Integrated Quasi 2π Active Monitoring. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:840. [PMID: 35055665 PMCID: PMC8776009 DOI: 10.3390/ijerph19020840] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 01/02/2022] [Accepted: 01/07/2022] [Indexed: 11/16/2022]
Abstract
In this work, a novel approach for the standardization of low-level 222Rn emanation is presented. The technique is based on the integration of a 222Rn source, directly, with an α-particle detector, which allows the residual 222Rn to be continuously monitored. Preparation of the device entails thermal physical vapor deposition of 226RaCl2 directly onto the surface of a commercially available ion implanted Si-diode detector, resulting in a thin-layer geometry. This enables continuous collection of well resolved α-particle spectra of the nuclei, decaying within the deposited layer, with a detection efficiency of approximately 0.5 in a quasi 2π geometry. The continuously sampled α-particle spectra are used to derive the emanation by statistical inversion. It is possible to achieve this with high temporal resolution due to the small background and the high counting efficiency of the presented technique. The emanation derived in this way exhibits a dependence on the relative humidity of up to 15% in the range from 20% rH to 90% rH. Traceability to the SI is provided by employing defined solid-angle α-particle spectrometry to characterize the counting efficiency of the modified detectors. The presented technique is demonstrated to apply to a range covering the release of at least 1 to 210 222Rn atoms per second, and it results in SI-traceable emanation values with a combined standard uncertainty not exceeding 2%. This provides a pathway for the realization of reference atmospheres covering typical environmental 222Rn levels and thus drastically improves the realization and the dissemination of the derived unit of the activity concentration concerning 222Rn in air.
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Affiliation(s)
- Florian Mertes
- Physikalisch-Technische Bundesanstalt, National Metrology Institute, 38116 Braunschweig, Germany; (S.R.); (A.R.)
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Mertes F, Kneip N, Heinke R, Kieck T, Studer D, Weber F, Röttger S, Röttger A, Wendt K, Walther C. Ion implantation of 226Ra for a primary 222Rn emanation standard. Appl Radiat Isot 2021; 181:110093. [PMID: 34995841 DOI: 10.1016/j.apradiso.2021.110093] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 12/02/2021] [Accepted: 12/28/2021] [Indexed: 11/02/2022]
Abstract
Laser resonance ionization at the RISIKO 30 kV mass separator has been used to produce isotopically and isobarically pure and well quantified 222Rn emanation standards. Based upon laser-spectroscopic preparation studies, ion implantation into aluminum and tungsten targets has been carried out, providing overall implantation efficiencies of 40% up to 60%. The absolute implanted activity of 226Ra was determined by the technique of defined solid-angle α-particle spectrometry, where excellent energy resolution was observed. The 222Rn emanation coefficient of the produced targets was studied using α-particle and γ-ray spectrometry, and yielded results between 0.23 and 0.34, with relative uncertainty on the order of 1%. No dependence exceeding a 1% change of the emanation on humidity could be identified in the range of 15 %rH to 75 %rH, whereas there were hints of a slight correlation between the emanation and temperature. Additionally, and as expected, the emanation coefficient was found to be dependent on the target material as well as the implanted dose.
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Affiliation(s)
- Florian Mertes
- Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116, Braunschweig, Germany.
| | - Nina Kneip
- Johannes Gutenberg-Universität Mainz, Institut für Physik, Staudingerweg 7, 55128, Mainz, Germany
| | - Reinhard Heinke
- Johannes Gutenberg-Universität Mainz, Institut für Physik, Staudingerweg 7, 55128, Mainz, Germany
| | - Tom Kieck
- Johannes Gutenberg-Universität Mainz, Institut für Physik, Staudingerweg 7, 55128, Mainz, Germany
| | - Dominik Studer
- Johannes Gutenberg-Universität Mainz, Institut für Physik, Staudingerweg 7, 55128, Mainz, Germany
| | - Felix Weber
- Johannes Gutenberg-Universität Mainz, Institut für Physik, Staudingerweg 7, 55128, Mainz, Germany
| | - Stefan Röttger
- Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116, Braunschweig, Germany
| | - Annette Röttger
- Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116, Braunschweig, Germany
| | - Klaus Wendt
- Johannes Gutenberg-Universität Mainz, Institut für Physik, Staudingerweg 7, 55128, Mainz, Germany
| | - Clemens Walther
- Leibniz Universität Hannover, Institut für Radioökologie und Strahlenschutz, 30419, Hannover, Germany
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Pommé S, Paepen J, Marouli M. Conversion electron spectroscopy of the 59.54 keV transition in 241Am alpha decay. Appl Radiat Isot 2019; 153:108848. [PMID: 31442878 DOI: 10.1016/j.apradiso.2019.108848] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 07/30/2019] [Accepted: 08/08/2019] [Indexed: 11/19/2022]
Abstract
A windowless Peltier-cooled silicon drift detector (SDD) was used to measure internal conversion electron (ICE) spectra of thin 241Am sources. The ICE peaks associated with the 59.54 keV gamma transition in 237Np were deconvoluted and relative ICE intensities were derived from the fitted peak areas. Corrections were made for energy dependence of the full-energy-peak counting efficiency, based on Monte Carlo simulations. As expected for this anomalous E1 transition, a significant discrepancy was found with the theoretical internal conversion coefficient (ICC) values calculated from the BrIcc database. Penetration effects are known to cause such anomalies in highly retarded transitions. The measured ICE intensities are in good agreement with a specific combination of literature data obtained with magnetic spectrometers.
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Affiliation(s)
- S Pommé
- European Commission, Joint Research Centre (JRC), Geel, Belgium.
| | - J Paepen
- European Commission, Joint Research Centre (JRC), Geel, Belgium
| | - M Marouli
- European Commission, Joint Research Centre (JRC), Geel, Belgium
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Pommé S, Marouli M, Paepen J, Marković N, Pöllänen R. Deconvolution of 238,239,240Pu conversion electron spectra measured with a silicon drift detector. Appl Radiat Isot 2017; 134:233-239. [PMID: 28964594 DOI: 10.1016/j.apradiso.2017.08.033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 08/24/2017] [Accepted: 08/24/2017] [Indexed: 11/19/2022]
Abstract
Internal conversion electron (ICE) spectra of thin 238,239,240Pu sources, measured with a windowless Peltier-cooled silicon drift detector (SDD), were deconvoluted and relative ICE intensities were derived from the fitted peak areas. Corrections were made for energy dependence of the full-energy-peak counting efficiency, based on Monte Carlo simulations. A good agreement was found with the theoretically expected internal conversion coefficient (ICC) values calculated from the BrIcc database.
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Affiliation(s)
- S Pommé
- European Commission, Joint Research Centre, Directorate for Nuclear Safety and Security, Retieseweg 111, B-2440 Geel, Belgium.
| | - M Marouli
- European Commission, Joint Research Centre, Directorate for Nuclear Safety and Security, Retieseweg 111, B-2440 Geel, Belgium
| | - J Paepen
- European Commission, Joint Research Centre, Directorate for Nuclear Safety and Security, Retieseweg 111, B-2440 Geel, Belgium
| | - N Marković
- European Commission, Joint Research Centre, Directorate for Nuclear Safety and Security, Retieseweg 111, B-2440 Geel, Belgium; Technical University of Denmark, Center for Nuclear Technologies, Radioecology Department, Roskilde, Denmark
| | - R Pöllänen
- Department of Physics, University of Helsinki, P.O. Box 9, FIN-00014, Finland
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