Terrestrial Radioactivity and Gamma-ray Exposure in the United States and Canada: Gridded geographic images

Aerial gamma-ray surveys measure the gamma-ray flux produced by the radioactive decay of the naturally occurring elements K-40, U-238, and Th-232 in the top few centimeters of rock or soil. If the gamma-ray system is properly calibrated the data can be expressed in terms of the estimated concentrations of the radioactive elements. A ternary color-composite image was generated by commercial software Geosoft Oasismontaj to map the combination of all three elements. During the period 1975-83, the U.S. Department of Energy carried out the National Uranium Resource Evaluation (NURE) Program, which included aerial gamma-ray surveys of most of the United States. These data were reprocessed to generate this product.航空伽马射线勘探（Aerial gamma-ray surveys）通过检测岩石或土壤表层数厘米内天然存在的钾-40（K-40）、铀-238（U-238）以及钍-232（Th-232）的放射性衰变所产生的伽马射线通量。若伽马射线探测系统经过正确校准，则所得数据可表示为各放射性元素的估算浓度。研究人员借助商业软件Geosoft Oasismontaj生成了一张三元彩色合成图像，以映射这三种元素的组合分布。 1975年至1983年间，美国能源部（U.S. Department of Energy）实施了国家铀资源评价（National Uranium Resource Evaluation, NURE）计划，该计划涵盖了美国绝大多数区域的航空伽马射线勘探工作。本次数据集正是基于经重新处理的上述原始勘探数据生成。