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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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Abstract
AbstractThe half-life of 243Am has been measured by an absolute and a relative method, i.e. by determining the specific activity of 243Am and the specific activity ratio with 241Am. A mixed 241,243Am reference material was produced and certified for its americium mass content and its isotope amount ratios. The characterisation of the mass content of 243Am was established by isotope dilution mass spectrometry using an 241Am spike, produced from highly enriched 241Pu material. The isotope amount ratios n(241Am)/n(243Am) and n(242mAm)/n(243Am) were measured by thermal ionisation mass spectrometry. Activity measurements were performed by alpha-particle counting at a defined solid angle, as well as high-resolution alpha-particle spectrometry. From the 243Am/241Am activity and isotopic amount ratios, a value of 16.988 (24) was derived for the 243Am/241Am half-life ratio. Using a value of 432.6 (6) a for the 241Am half-life, the corresponding 243Am half-life value, 7349 (15) a, is in good agreement with the result obtained from the absolute method, 7342 (14) a. The mean value, 7345 (14) a, agrees well with data from literature and lowers the relative standard uncertainty to 0.2%.
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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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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, Paepen J, Peräjärvi K, Turunen J, Pöllänen R. Conversion electron spectrometry of Pu isotopes with a silicon drift detector. Appl Radiat Isot 2015; 109:183-188. [PMID: 26651177 DOI: 10.1016/j.apradiso.2015.11.052] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Accepted: 11/20/2015] [Indexed: 11/30/2022]
Abstract
An electron spectrometry set-up was built at IRMM consisting of a vacuum chamber with a moveable source holder and windowless Peltier-cooled silicon drift detector (SDD). The SDD is well suited for measuring low-energy x rays and electrons emitted from thin radioactive sources with low self-absorption. The attainable energy resolution is better than 0.5keV for electrons of 30keV. It has been used to measure the conversion electron spectra of three plutonium isotopes, i.e. (238)Pu, (239)Pu, (240)Pu, as well as (241)Am (being a decay product of (241)Pu). The obtained mixed x-ray and electron spectra are compared with spectra obtained with a close-geometry set-up using another SDD in STUK and spectra measured with a Si(Li) detector at IRMM. The potential of conversion electron spectrometry for isotopic analysis of mixed plutonium samples is investigated. With respect to the (240)Pu/(239)Pu isotopic ratio, the conversion electron peaks of both isotopes are more clearly separated than their largely overlapping peaks in alpha spectra.
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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.
| | - J Paepen
- European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel, Belgium
| | - K Peräjärvi
- STUK-Radiation and Nuclear Safety Authority, P.O. Box 14, FI-00881 Helsinki, Finland
| | - J Turunen
- STUK-Radiation and Nuclear Safety Authority, P.O. Box 14, FI-00881 Helsinki, Finland
| | - R Pöllänen
- STUK-Radiation and Nuclear Safety Authority, P.O. Box 14, FI-00881 Helsinki, Finland
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Pommé S, García-Toraño E, Marouli M, Crespo M, Jobbágy V, Van Ammel R, Paepen J, Stroh H. High-resolution alpha-particle spectrometry of 238U. Appl Radiat Isot 2014; 87:315-9. [DOI: 10.1016/j.apradiso.2013.11.075] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Accepted: 11/17/2013] [Indexed: 11/28/2022]
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Caro Marroyo B, Martín Sánchez A, Jurado Vargas M. Improvements to alpha-particle spectrometry techniques. Appl Radiat Isot 2014; 87:328-30. [DOI: 10.1016/j.apradiso.2013.11.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Accepted: 11/09/2013] [Indexed: 11/29/2022]
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Marouli M, Pommé S, Jobbágy V, Van Ammel R, Paepen J, Stroh H, Benedik L. Alpha-particle emission probabilities of 236U obtained by alpha spectrometry. Appl Radiat Isot 2014; 87:292-6. [DOI: 10.1016/j.apradiso.2013.11.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Accepted: 11/09/2013] [Indexed: 11/25/2022]
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