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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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García-Toraño E, Crespo T, Marouli M, Jobbágy V, Pommé S, Ivanov P. Alpha-particle emission probabilities of 231Pa derived from first semiconductor spectrometric measurements. Appl Radiat Isot 2019; 154:108863. [PMID: 31513990 DOI: 10.1016/j.apradiso.2019.108863] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 08/12/2019] [Accepted: 08/14/2019] [Indexed: 11/24/2022]
Abstract
The nuclide 231Pa is a member of the 235U decay chain. It is a complex alpha emitter with 25 identified alpha emissions. Formerly published alpha-particle emission probabilities were derived from measurements taken with magnetic spectrometers. This work presents the first measurements made with semiconductor detectors. High-resolution alpha-particle spectrometry was carried out at CIEMAT and JRC using ion-implanted planar silicon detectors. Alpha-particle emission probabilities of 23 transitions were derived from deconvolutions of the spectra. For the major lines, uncertainties are lower than 1%, a significant improvement to existing data. The new data set will allow a more accurate evaluation of the decay scheme of 231Pa.
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Affiliation(s)
| | - T Crespo
- Ciemat, Avenida Complutense 40, 28040, Madrid, Spain
| | - M Marouli
- European Commission, Joint Research Centre (JRC), Geel, Belgium
| | - V Jobbágy
- European Commission, Joint Research Centre (JRC), Geel, Belgium
| | - S Pommé
- European Commission, Joint Research Centre (JRC), Geel, Belgium
| | - P Ivanov
- National Physical Laboratory (NPL), Teddington, UK
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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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Marouli M, Pommé S, Van Ammel R, García-Toraño E, Crespo T, Pierre S. Direct measurement of alpha emission probabilities in the decay of 226Ra. Appl Radiat Isot 2017; 125:196-202. [PMID: 28476016 DOI: 10.1016/j.apradiso.2017.04.029] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 04/18/2017] [Accepted: 04/26/2017] [Indexed: 10/19/2022]
Abstract
High-resolution alpha-particle spectrometry was performed to determine the main alpha-particle emission probabilities in the decay of 226Ra. Thin, homogeneous sources were prepared by electrodeposition on stainless steel disks. Alpha spectra with an energy resolution of 20keV were obtained in three laboratories and analysed with different deconvolution algorithms. In two set-ups, a magnet system was used to deflect conversion electrons to avoid their coincidental detection with the alpha particles. Spectra taken at close range without a magnet system yielded biased results which cannot be fully compensated by statistical corrections for coincidence summing. The derived emission probabilities of the three main alpha decays are 94.07 (1)%, 5.93 (1)%, and 0.0059 (15)%, respectively. They are in excellent agreement with calculated values derived from the P(γ+ce) decay scheme balance, which solves the existing discrepancy problem with two previous direct measurements published in literature.
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Affiliation(s)
- M Marouli
- European Commission, Joint Research Centre, Directorate for Nuclear Safety and Security, Retieseweg 111, B-2440 Geel, Belgium
| | - S Pommé
- European Commission, Joint Research Centre, Directorate for Nuclear Safety and Security, Retieseweg 111, B-2440 Geel, Belgium.
| | - R Van Ammel
- European Commission, Joint Research Centre, Directorate for Nuclear Safety and Security, Retieseweg 111, B-2440 Geel, Belgium
| | - E García-Toraño
- Laboratorio de Metrología de Radiaciones Ionizantes, CIEMAT, Avenida Complutense 40, 28040 Madrid, Spain
| | - T Crespo
- Laboratorio de Metrología de Radiaciones Ionizantes, CIEMAT, Avenida Complutense 40, 28040 Madrid, Spain
| | - S Pierre
- BNM-CEA/Laboratoire National Henri Becquerel, F-91191 Gif-sur-Yvette Cedex, France
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Pommé S, Caro Marroyo B. Improved peak shape fitting in alpha spectra. Appl Radiat Isot 2014; 96:148-153. [PMID: 25497323 DOI: 10.1016/j.apradiso.2014.11.023] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 11/17/2014] [Accepted: 11/27/2014] [Indexed: 10/24/2022]
Abstract
Peak overlap is a recurrent issue in alpha-particle spectrometry, not only in routine analyses but also in the high-resolution spectra from which reference values for alpha emission probabilities are derived. In this work, improved peak shape formulae are presented for the deconvolution of alpha-particle spectra. They have been implemented as fit functions in a spreadsheet application and optimum fit parameters were searched with built-in optimisation routines. Deconvolution results are shown for a few challenging spectra with high statistical precision. The algorithm outperforms the best available routines for high-resolution spectrometry, which may facilitate a more reliable determination of alpha emission probabilities in the future. It is also applicable to alpha spectra with inferior energy resolution.
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Affiliation(s)
- S Pommé
- European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel, Belgium.
| | - B Caro Marroyo
- Laboratorio de Metrología de Radiaciones Ionizantes, CIEMAT, Avenida Complutense 22, 28040 Madrid, Spain
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