Exploration of activity measurements and equilibrium checks for sediment dating using thick-window Germanium detectors

Date

2011

Authors

Warner, Jacob A
Fitzsimmons, Kathryn
Reynolds, Eva
Gladkis, Laura
Timmers, Heiko

Journal Title

Journal ISSN

Volume Title

Publisher

American Institute of Physics (AIP)

Abstract

Activity measurements on sediment samples for trapped-charge geological dating using gamma-ray spectroscopy are an important verification of the field-site dose rate determination. Furthermore gamma-ray spectroscopy can check if the natural decay series are in secular equilibrium which is a crucial assumption in such dating. Typically the activities of leading members of the Thorium and Uranium decay series are measured, which requires Germanium detectors with thin windows and good energy resolution in order to effectively detect the associated low energy gamma-rays. Such equipment is not always readily available. The potential of conventional Germanium detectors with thick entrance window has been explored towards routine gamma-ray spectroscopy of sediment samples using higher energy gamma-rays. Alternative isotopes, such as Ac-228 and Pb-212 for the Thorium series, and Pa-234m, Ra-226 and Bi-214 for the Uranium series, have been measured in order to determine the mass-specific activity for the respective series and possibly provide a check of secular equilibrium. In addition to measurements of the K-40 activity, with the alternative approach, the activities of both decay series can be accurately determined. The secular equilibrium condition may be tested for the Thorium series. Measurement accuracy for Pa-234m is, however, not sufficient to permit also a reliable check of equilibrium for the Uranium series.

Description

Keywords

Keywords: Gamma-ray detection; Luminescence dating; Natural decay series; Trapped-charge dating

Citation

Source

AIP Conference Proceedings

Type

Conference paper

Book Title

Entity type

Access Statement

License Rights

DOI

10.1063/1.3586091

Restricted until

2037-12-31