title: Application of deuteron-deuteron (D-D) fusion neutrons to 40Ar/39Ar geochronology.
abstract: Neutron irradiation of samples for 40Ar/39Ar dating in a 235U fission reactor requires error-producing corrections for the argon isotopes created from Ca, K, and, to a lesser extent, Cl. The fission spectrum includes neutrons with energies above 2-3 MeV, which are not optimal for the 39K(n,p)39Ar reaction. These higher-energy neutrons are responsible for the largest recoil displacements, which may introduce age artifacts in the case of fine-grained samples. Both interference corrections and recoil displacements would be significantly reduced by irradiation with 2.45 MeV neutrons, which are produced by the deuteron-deuteron (D-D) fusion reaction 2H(d,n)3He. A new generation of D-D reactors should yield sufficiently high neutron fluxes (>10(12) n cm(-2)s(-1)) to be useful for 40Ar/39Ar dating. Modeling indicates that irradiation with D-D neutrons would result in scientific benefits of improved accuracy and broader applicability to fine-grained materials. In addition, radiological safety would be improved, while both maintenance and operational costs would be reduced. Thus, development of high-flux D-D fusion reactors is a worthy goal for 40Ar/39Ar geochronology.
authors.affiliation: Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, CA 94709, USA. prenne@bgc.org
authors.forename: Paul R
authors.initials: PR
authors.lastname: Renne
authors.forename: Kim B
authors.initials: KB
authors.lastname: Knight
authors.forename: Sébastien
authors.initials: S
authors.lastname: Nomade
authors.forename: Ka-Ngo
authors.initials: KN
authors.lastname: Leung
authors.forename: Tak-Pui
authors.initials: TP
authors.lastname: Lou