Short-lived isotope analytical facility (gamma well counter)

目前的申请是购买一个伽马射线计数器，配备一个形状良好的锗探测器，计数效率高达90%，用于测量大量自然和/或人为来源的短寿命放射性同位素。因此，该仪器将专门用于非常低水平的放射性计数，即小样本和/或低放射性同位素丰度。天然同位素（如210Pb、7Be、226Ra、228Ra、234）以及与核活动有关的同位素（如137Cs）的测量对于以下方面至关重要：测定非常年轻的湖泊和海洋沉积物的年代，记录底栖生物过程，评估沉积物的位移和积累速率，计算洞穴或热液沉积物的生长速率，确定颗粒运输速率，以及溶解的有机物质的速率，评估土壤中的溶解速率和生态系统中放射性污染物的积累速率和行为……这种广泛的使用导致了湖沼学、海洋学、土壤和环境科学研究人员的大量分析需求。与其他分析技术相比，伽马能谱法的优势在于，该方法不具有破坏性，因此样品可以重复使用，用于进一步的生物、地质、元素或同位素分析。堪培拉的伽马探测器是一种专用的“交钥匙”仪器，可以最大限度地利用仪器并产生高质量的结果。与旧的伽马仪器相比，该设备提供了一个更灵敏的探测器，可以接受更大体积的样品（高达10cc vs. 1cc），从而允许减少计数次数并实现更好的精度。GEOTOP的放射性同位素实验室需要这台仪器来满足每年平均25名来自魁北克各学术机构的研究人员和研究生不断增长的分析需求，这些研究人员和研究生每年都要求我们的设施进行这些分析。

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.