Short-lived isotope analytical facility (gamma well counter)

本申请用于购买配备形状良好的锗探测器的伽马射线计数器，该探测器产生高达90%的计数效率，用于测量大量天然和/或人为来源的短寿命放射性同位素。因此，该仪器将专门用于极低水平的放射性计数，即对小样本和/或低放射性同位素丰度的计数。测量天然同位素(如210Pb、7Be、226Ra、228Ra、234)以及与核活动有关的同位素(如137Cs)对于以下方面至关重要：对非常年轻的湖泊和海洋沉积物进行测年，记录海底生物过程，评估沉积物置换和累积速率，计算洞穴或热液沉积的生长速率，确定颗粒迁移速率以及溶解有机物的生长速率，评估土壤中的溶解速率和生态系统中放射性污染物的累积速率和行为。这种广泛的用途导致了湖泊学、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，伽马光谱分析的优势在于，这种方法是不具破坏性的，因此样品可以重复用于进一步的生物、地质、元素或同位素分析。将在这里购买的堪培拉伽马探测器是一种专用的“交钥匙”仪器，它最大限度地提高了仪器的利用率，并产生了高质量的结果。与老式伽马仪器相比，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比1cc)，从而减少计数时间并实现更高的精度。GEOTOP的放射性同位素实验室需要这台仪器来满足魁北克各学术机构的平均25名研究人员和研究生日益增长的分析需求，他们每年都需要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.