Short-lived isotope analytical facility (gamma well counter)

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The present application is for the purchase of a gamma-ray counter equipped with a well-shaped germanium detector yielding counting efficiencies up to 90% for the measurement of a large array of short-lived radioisotopes of natural and/or anthropogenic sources. The instrument will thus be dedicated to very low-level counting of radioactivity, i.e., to small samples and/or low radioisotope abundances. The measurement of natural isotopes (e.g., 210Pb, 7Be, 226Ra, 228Ra, 234Th) as well as of isotopes linked to nuclear activities (e.g., 137Cs), is essential for: the dating of very young lacustrine and oceanic sediment, documenting benthic biological processes, the assessment of sediment displacement and accumulation rates, calculating growth rates of cave or hydrothermal deposits, determining particulate transport rates, as well as those of dissolved organic substances, assessing dissolution rates in soils and the accumulation rates and behavior of radioactive contaminants in ecosystems... This wide spectrum of use results in large analytical needs from researchers in limnology, oceanography, soil and environmental sciences. The advantage of gamma spectrometry over other analytical techniques, whenever they exist, is that the method is not destructive, so the sample can be reused for further biological, geological, elemental or isotopic analyses. The Canberra's gamma detector to be purchased here is a dedicated "turnkey" instrument, which maximizes instrument utilization and produces high quality results. Compared to older gamma instruments, this device offers a much more sensitive detector that can accept larger volume samples (up to 10cc vs. 1cc), thus permitting to reduce counting times and achieve a better precision. The radioisotope laboratory of GEOTOP needs this instrument to address the increasing analytical needs of an average of 25 researchers and graduate students from various academic Quebec institutions that call on our facility each year for these analyses.