title: Direct measurement of the half-life of (223)Ra.
abstract: Radioactive decay half-life measurements of (223)Ra, a member of the (235)U naturally occurring radioactive decay series, have been performed of a radiochemically pure solution with an ionisation chamber. The radioactive decay of (223)Ra was followed for 50 days, approximately 4.4 half-lives. The deduced half-life of (223)Ra was found to be 11.4358 (28) days, supporting the other published direct measurements. A detailed uncertainty budget is presented. A new evaluation of the published half-life values was performed, indicating significant variation across the existing published values, suggesting that further measurements of the half-life of (223)Ra are required. A new evaluated half-life has been calculated using a power moderated weighted mean of selected experimental values, with a new value of the recommended half-life for (223)Ra of 11.4354 (17) days.
authors.affiliation: National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, United Kingdom. Electronic address: sean.collins@npl.co.uk.
authors.forename: S M
authors.initials: SM
authors.lastname: Collins
authors.affiliation: National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, United Kingdom.
authors.forename: A K
authors.initials: AK
authors.lastname: Pearce
authors.affiliation: National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, United Kingdom.
authors.forename: K M
authors.initials: KM
authors.lastname: Ferreira
authors.affiliation: National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, United Kingdom.
authors.forename: A J
authors.initials: AJ
authors.lastname: Fenwick
authors.affiliation: National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, United Kingdom; Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom.
authors.forename: P H
authors.initials: PH
authors.lastname: Regan
authors.affiliation: National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, United Kingdom.
authors.forename: J D
authors.initials: JD
authors.lastname: Keightley
keywords: (223)Ra; Half-life; Ionisation chamber; NORM; Nuclear data; Nuclear medicine; Radioactivity