Abstract
Abstract 32Si (T 1/2 = 153(19) y) is an extremely rare, naturally-occurring isotope that has been considered as a geochronometer suitable for radiometric dating over the time span from 100 to 1000 years ago – a time span that has proved rather difficult to explore in this manner. Past attempts to determine the 32Si half-life have resulted in a wide range of values possessing significant uncertainties because only low-activity samples could be made available for such measurements. Utilizing the 590 MeV ring cyclotron at PSI, megabecquerel quantities of 32Si have been produced by exposing metallic vanadium discs to high-energy protons in order to induce spallation. A radiochemical separation procedure has been successfully developed and applied to the irradiated discs as part of the SINCHRON project, based on a combination of ion-exchange and extraction resins. The process was shown to be reliable and robust with a high chemical yield. Radiochemically pure 32Si solutions with activity concentrations of up to several kBq/g can be produced to perform individual measurements (AMS, ICP-MS, LSC) for various studies. Thus, a careful redetermination of the 32Si half-life has become feasible to begin the first steps toward the confident implementation of this radionuclide for geochronological purposes.
Highlights
Radiometric dating has proved to be a versatile tool, which is well-known, for instance, for radiocarbon (14C), potassium-argon (40K/40Ar), and uranium-lead (e.g., 238U/206Pb) dating
32Si (T1/2 = 153(19) y) is an extremely rare, naturally-occurring isotope that has been considered as a geochronometer suitable for radiometric dating over the time span from 100 to 1000 years ago – a time span that has proved rather difficult to explore in this manner
150 vanadium discs were used as targets in the SINQ Target Irradiation Program (STIP) [14], using Paul Scherrer Institut (PSI)’s High-Intensity Proton Accelerator (HIPA), and all simultaneously exposed to high-energy protons (Emax = 590 MeV) over two years (2010–2012)
Summary
Radiometric dating has proved to be a versatile tool, which is well-known, for instance, for radiocarbon (14C), potassium-argon (40K/40Ar), and uranium-lead (e.g., 238U/206Pb) dating. Because of their individual half-lives, an accurate age determination in the range of 100–1000 years has not yet been established, resulting in a visible dating gap (Figure 1a). Proton-irradiation produces 32Si, and other rare radionuclides, such as 26Al, 41Ca, and 44Ti/44Sc. Due to the long-term exposure of the V-discs at the PSI facility, extensive amounts of these nuclides were produced, with particular interest focused on 32Si. Here, we report on the artificial production of a significant amount of 32Si, and the subsequent development of a reliable, robust chemical separation procedure to provide radiochemically pure 32Si solutions with high activity concentrations. Our aim in the future will be to provide a new recommended half-life value with a relative standard uncertainty of less than 5%
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
