New measurement of the 238U decay constant with inductively coupled plasma mass spectrometry
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The 238U decay constant (λU-238) is fundamental to radioisotope-based chronometry in the Earth and planetary sciences, yet only a single published λU-238 value (Jaffey et al. in Phys Rev C 4(5):1889–1906, 1971) is widely applied. We have determined λU-238 via the novel approach of measuring of 234Th ingrowth in high-purity 238U solutions, using isotope dilution mass spectrometry (ID-MS). The 234Th decay constant (λTh-234) was measured via decay counting with high-purity Ge (HPGe) γ detectors. Preliminary results for λU-238 agree with the value determined by α-counting  within the elevated uncertainty of 0.462% (k = 2). Ongoing efforts to reproduce λU-238 with reduced experimental uncertainties will inform future conclusions.
KeywordsUranium Thorium Half-life Decay constant Radiochronometry Inductively coupled plasma mass spectrometry
This document, LLNL-JRNL-752487, was prepared by LLNL under Contract DE-AC52-07NA27344. The authors thank Dave Ruddle of LLNL for engineering support, and T. Mark Harrison of the University of California, Los Angeles for his early support in advocating the needs of geochronology. This work was supported by LLNL’s laboratory directed research and development (LDRD) program (16-LW-053). TPD also gratefully acknowledges support from the US Department of Homeland Security National Technical Nuclear Forensics Center post-doctoral fellowship.
- 2.Harrison TM, Baldwin SL, Caffee M, Gehrels GE, Schoene B, Shuster DL, Singer BS (2015) It’s about time: opportunities and challenges for U.S. Geological Survey. Institute of Geophysics and Planetary Physics Publication 6539, University of California, Los AngelesGoogle Scholar
- 9.Holden N (1981) The uranium half-lives: a critical review. Information Analysis Center Report, National Nuclear Data Center, Brookhaven National Laboratory, Upton, NY. BNL-NCS-51320Google Scholar
- 12.Kirsch G (1920) Mitt. Ra. Inst. 127 Wien. Ber. 11a, 129, 309, M-Sch.: 377Google Scholar
- 13.Sargent BW (1939) Can J Res A 369:527–533Google Scholar
- 15.Verbruggen A, Alonso A, Eykens R, Kehoe F, Kühn H, Richter S, Aregbe Y (2008) Preparation and Certification of IRMM-3636, IRMM-3636a, and IRMM-3636b, JRC technical report 45903, EUR 23408 EN, ISSN 1018-5593. European Communities, BelgiumGoogle Scholar
- 16.Certificate of Analysis for NIST SRM 4342A. https://www-s.nist.gov/srmors/certificates/4342A.pdf
- 17.Certificate of Analysis for New Brunswick Laboratories U010. https://science.energy.gov/~/media/nbl/pdf/price-lists/certificates/CRM_U010_5_Milligram_Sample_Size_March_2008.pdf
- 18.Bateman H (1910) The solution of a system of differential equations occurring in the theory of radioactive transformations. In: Proceedings of the Cambridge Philosophical Society 15(V): 423–427. https://archive.org/details/cbarchive_122715_solutionofasystemofdifferentia1843
- 25.Steyn J, Strelow FWE (1960) The determination of the half-life of 238U, absolute counting of α particles in a 4π-liquid scintillation counter. In: Sanielevici A (Ed) Metrology of radionuclides. IAEA STI/PUB/6, Vienna, Austria, pp 155–161Google Scholar