Measurement of absolute γ-ray emission probabilities in the decay of 235U

M Marouli; G Lutter; S Pommé; R Van Ammel; M Hult; S Richter; R Eykens; V Peyrés; E García-Toraño; P Dryák; M Mazánová; P Carconi

doi:10.1016/j.apradiso.2017.10.049

Measurement of absolute γ-ray emission probabilities in the decay of ²³⁵U

Appl Radiat Isot. 2018 Feb:132:72-78. doi: 10.1016/j.apradiso.2017.10.049. Epub 2017 Oct 29.

Authors

M Marouli¹, G Lutter¹, S Pommé², R Van Ammel¹, M Hult¹, S Richter¹, R Eykens¹, V Peyrés³, E García-Toraño³, P Dryák⁴, M Mazánová⁴, P Carconi⁵

Affiliations

¹ European Commission, Joint Research Centre, JRC, Directorate for Nuclear Safety and Security, Retieseweg 111, B-2440 Geel, Belgium.
² European Commission, Joint Research Centre, JRC, Directorate for Nuclear Safety and Security, Retieseweg 111, B-2440 Geel, Belgium. Electronic address: stefaan.pomme@ec.europa.eu.
³ Laboratorio de Metrología de Radiaciones Ionizantes, CIEMAT, Avenida Complutense 40, 28040 Madrid, Spain.
⁴ Český Metrologický Institut, CMI, Radiová 1, 102 00 Praha 10, Czech Republic.
⁵ ENEA, Instituto Nazionale di Metrologia delle Radiazioni Ionizzanti, C.R. Casaccia, P.O. Box 2400, I-00100 Rome A.D., Italy.

PMID: 29169063
DOI: 10.1016/j.apradiso.2017.10.049

Abstract

Accurate measurements were performed of the photon emission probabilities following the α decay of ²³⁵U to ²³¹Th. Sources of highly enriched ²³⁵U were characterised in terms of isotopic composition by mass spectrometry and their activities were standardised by means of alpha-particle counting at a low defined solid angle. The standardised sources were subsequently measured by high-resolution γ-ray spectrometry with calibrated high-purity germanium detectors to determine the photon emission probabilities. Four laboratories participated in this work and reported emission probabilities for 33 γ-ray lines. Most of them agree with previously published evaluated data. In addition, new values are proposed for γ-lines which have been measured only once in the past.

Keywords: (231)Th; (235)U; Decay data; γ-ray emission probabilities, NORM; γ-ray spectrometry.