title: Mobility determination of lead isotopes in glass for retrospective radon measurements.
abstract: In retrospective radon measurements, the 22-y half life of (210)Pb is used as an advantage. (210)Pb is often considered to be relatively immobile in glass after alpha recoil implanted by (222)Rn progenies. The diffusion of (210)Pb could, however, lead to uncertain wrong retrospective radon exposure estimations if (210)Pb is mobile and can escape from glass, or lost as a result of cleaning-induced surface modification. This diffusion was studied by a radiotracer technique, where (209)Pb was used as a tracer in a glass matrix for which the elemental composition is known. Using the ion guide isotope separator on-line technique, the (209)Pb atoms were implanted into the glass with an energy of 39 keV. The diffusion profiles and the diffusion coefficients were determined after annealing at 470-620 degrees C and serial sectioning by ion sputtering. In addition, the effect of surface cleaning on diffusion was tested. From the Arrhenius fit, the activation enthalpy (H) was determined, which is equal to 3.2 +/- 0.2 eV, and also the pre-exponential factor D(0), in the order of 20 m(2)s(-1). This result confirms the assumption that over a time period of 50 y (209)Pb (and (210)Pb) is effectively immobile in the glass. The boundary condition obtained from the measurements had the characteristic of a sink, implying loss of (209)Pb in the topmost surface at high temperatures.
authors.affiliation: Department of Physics, University of Jyväskylä (JYLF), P.O. Box 35, FIN-40014 Jyväskylä, Finland. mikko.laitinen@jyu.fi
authors.forename: Mikko
authors.initials: M
authors.lastname: Laitinen
authors.forename: Iiro
authors.initials: I
authors.lastname: Riihimäki
authors.forename: Jörgen
authors.initials: J
authors.lastname: Ekman
authors.forename: A R Ananda
authors.initials: AR
authors.lastname: Sagari
authors.forename: Lennart B
authors.initials: LB
authors.lastname: Karlsson
authors.forename: Somjai
authors.initials: S
authors.lastname: Sangyuenyongpipat
authors.forename: Sergey
authors.initials: S
authors.lastname: Gorelick
authors.forename: Heikki
authors.initials: H
authors.lastname: Kettunen
authors.forename: Heikki
authors.initials: H
authors.lastname: Penttilä
authors.forename: Ragnar
authors.initials: R
authors.lastname: Hellborg
authors.forename: Timo
authors.initials: T
authors.lastname: Sajavaara
authors.forename: Johan
authors.initials: J
authors.lastname: Helgesson
authors.forename: Harry J
authors.initials: HJ
authors.lastname: Whitlow
mesh_terms: D017357:Cyclotrons; D003902:Detergents; D004058:Diffusion; D005898:Glass / Q000737:chemistry*; D007856:Lead Radioisotopes / Q000032:analysis*; D015233:Models, Statistical; D011874:Radiometry; D011886:Radon / Q000032:analysis*; D013696:Temperature; D013997:Time Factors
chemical_list: D003902:Detergents; D007856:Lead Radioisotopes; D011886:Radon