[en] The paper covers: a bit of basic physics; underlying principles of cosmogenic isotope techniques; atmospheric ¹⁰Be and ⁷Be; in situ ¹⁰Be, ²⁶Al, and ¹⁴C. 9 refs., 2 figs

[en] Presented are the 2001-02 activities of the National Isotope Centre at the Institute of Geological and Nuclear Sciences. Details are given of the 2000-04 facilities upgrade, and listed are the contributions of these facilities to science outcomes of New Zealand research programmes. The 4-year upgrade addresses (i) improvements of subsystems in the EN-tandem accelerator, such as the Pelletron conversion, (ii) improvements of accelerator beamlines, such as the microprobe-IBA setup attached to the KN / 3-MV accelerator, and (iii) capability expansions, such as a new ion implanter and a new stable-isotope mass spectrometer. The aim of these upgrades is to achieve improvements in analytical accuracy, sensitivity, and specificity, and in system flexibility and reliability. (author). 3 refs., 4 tabs

[en] Provides a brief explanation of the title of the article. Details the use and application of atmospheric ¹⁰Be and ⁷Be, the measurement of beryllium-9, beryllium-7, and beryllium-10, and in situ ¹⁰Be, ²⁶Al, and ¹⁴C. 9 refs., 2 figs

[en] The paper covers: a bit of basic physics; underlying principles of cosmogenic isotope techniques; atmospheric ¹⁰Be and ⁷Be; in situ ¹⁰Be, ²⁶Al, and ¹⁴C. 9 refs

[en] The present limitations to the sensitivity and detection limit for ¹⁰Be and ²⁶Al AMS, at the EN-tandem accelerator system of the Rafter national facility at GNS, are discussed. The dominant charge-exchange mechanisms are explained. Various test measurements focus on specific characteristics of the system that set these limits. The sensitivity for ¹⁰Be/⁹Be is near 1.10-14, at which point it takes more than 1 hour to reduce the Poisson error to 10%. Using the same definition, the sensitivity for ²⁶Al/²⁷Al is 2.10-13. Spectrum background from interferences with each of these rare isotopes are of the similar magnitude. The detection limit and sensitivity for ²⁶/Al requires substantial improvement before being useful for low-level AMS. The first step should be the installation of a new (magnetic-)electrostatic analyser system in front of the particle detection. (author). 18 refs., 19 figs., 3 tabs

[en] Methods for the analysis of Be and U-Th isotopes in loess are detailed, together with a discussion on precision and reproducibility, leaching vs. whole-rock decomposition, and grainsize fraction vs. whole rock analysis. (author). 17 refs., 5 tabs

[en] An introduction to radiocarbon dating, with notes on corrections for fractionation, for reservoir effects and for variation in "1"4C production over time. Includes a glossary of radiocarbon terms and a short bibliography.

[en] Establishment of surface exposure dating techniques using ¹⁰Be began at GNS in late 1996. Progress so far has seen the establishment of sample preparation methods, development of AMS techniques, and the completion of analytical trials. Considerable progress has been made towards improving ¹⁰Be analysis at low levels using the GNS tandem accelerator. Several modifications have been made to the AMS system to lower the detection limit for ¹⁰Be / ⁹Be ratio measurements by at least a factor 10, due to an improved suppression of the ⁹BeOH/⁹Be/³⁺ parasitic beam. With backgrounds of 2x10^-14 on standard blanks, uncorrected for ¹⁰B(¹H,⁴He)/⁷Be, low-level ¹⁰Be/⁹Be ratio measurements are now possible. Promising results for two small dating projects (case studies), the raised beaches at Turakirae Heads and Lake Hawea moraines, are reported and briefly discussed. (author)

[en] Traditionally, dating on-land soils (tills) in Antarctica has proved difficult due to a lack of suitable and reliable methods, and an absence of fixed points by which ages can be accurately determined. Cosmogenic isotopes, in particular ¹⁰Be, offer a solution to this problem through the application of surface exposure dating. Surface exposure dating of substrate, bouldery flows or tills can provide useful minimum ages, but is limited by uncertainties regarding production rates, degree of erosion and/or pre-existing snow/soil cover, and tectonism. Dating soils using ¹⁰Be has its own set of limitations, but a range of new interpretative approaches has recently yielded some promising results. However, it is difficult to accurately estimate ¹⁰Be flux, which can differ by orders of magnitude both spatially and over geological time. Alternatively ¹⁰Be/⁹Be ratios of easily leachable soil components, produced near the soil surface by equilibrium of atmospheric ¹⁰Be and common Be (⁹Be), may be presumed to be independent of ¹⁰Be flux. In soil of pH less than 5, this Be becomes relatively mobile and moves downwards slowly over several My, yielding ¹⁰Be/⁹Be decay curves from which age information can be inferred. An even more promising approach relies on an observed close correlation between ¹⁰Be ages, independent age estimations and nitrate inventories. The nitrate, like ¹⁰Be, is derived from chemical reactions in the stratosphere and is known to gradually accumulate with time in Antarctic soils as part of the total salt inventory. Evidence suggests that nitrate flux into the soils may be temporally and spatially constant. This suggests that, if they can be independently age calibrated (using ¹⁰Be/⁹Be), nitrate inventories could provide a reliable and widely applicable estimate of soil ages in Antarctica

[en] Radiometric dating is regarded as fundamental to any modern timescale calibration. In terms of available isotopic dating and tracing tools in environmental sciences, the cosmogenic isotopes stand out because of their application in the range from the very recent up to the middle Miocene. At IGNS, three long-lived cosmogenic isotopes can be measured. ¹⁴C (half life=5730 years) and ¹⁰Be (half-life = 1.5 Ma) are measured by Accelerator Mass Spectrometry (AMS) of ¹⁰Be/⁹Be and ¹⁴C/¹³C ratios, while ³²Si (half-life > 140 years) is measured by radioactive decay counting of its daughter-product ³²P. The main advantage of AMS over decay counting is the relatively small amount of sample material needed. AMS has made it feasible to measure ultra-low concentrations of long-lived isotopes such as ¹⁰Be. (author)