title: The production of Neptunium-236g.
abstract: Radiochemical analysis of (237)Np is important in a number of fields, such as nuclear forensics, environmental analysis and measurements throughout the nuclear fuel cycle. However analysis is complicated by the lack of a stable isotope of neptunium. Although various tracers have been used, including (235)Np, (239)Np and even (236)Pu, none are entirely satisfactory. However, (236g)Np would be a better candidate for a neptunium yield tracer, as its long half-life means that it is useable as both a radiometric and mass spectrometric measurements. This radionuclide is notoriously difficult to prepare, and limited in scope. In this paper, we examine the options for the production of (236g)Np, based on work carried out at NPL since 2011. However, this work was primarily aimed at the production of (236)Pu, and not (236g)Np and therefore the rate of production are based on the levels of (236)Pu generated in the irradiation of (i) (238)U with protons, (ii) (235)U with deuterons, (iii) (236)U with protons and (iv) (236)U with deuterons. The derivation of a well-defined cross section is complicated by the relevant paucity of information on the variation of the (236m)Np:(236g)Np production ratio with incident particle energy. Furthermore, information on the purity of (236g)Np so produced is similarly sparse. Accordingly, the existing data is assessed and a plan for future work is presented.
authors.affiliation: National Physical Laboratory, Teddington TW11 OLW, United Kingdom. Electronic address: simon.jerome@npl.co.uk.
authors.forename: S M
authors.initials: SM
authors.lastname: Jerome
authors.affiliation: National Physical Laboratory, Teddington TW11 OLW, United Kingdom.
authors.forename: P
authors.initials: P
authors.lastname: Ivanov
authors.affiliation: National Physical Laboratory, Teddington TW11 OLW, United Kingdom.
authors.forename: C
authors.initials: C
authors.lastname: Larijani
authors.affiliation: School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, United Kingdom.
authors.forename: D J
authors.initials: DJ
authors.lastname: Parker
authors.affiliation: National Physical Laboratory, Teddington TW11 OLW, United Kingdom; Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom.
authors.forename: P H
authors.initials: PH
authors.lastname: Regan
mesh_terms: D013058:Mass Spectrometry / Q000379:methods*; D009405:Neptunium / Q000737:chemistry*; D011849:Radioactive Tracers; D011874:Radiometry / Q000379:methods*; D014501:Uranium / Q000737:chemistry*
chemical_list: D011849:Radioactive Tracers; D014501:Uranium; D009405:Neptunium
keywords: Charged particle; Decay data; Isotope dilution; Neptunium; Nuclear structure; Radiochemical analysis; Tracer