A vast, largely invisible network of radiation-detection systems operates continuously across the United States and other countries, primarily focused on preventing nuclear terrorism. These systems range from small, portable sensors carried by first responders to sophisticated fixed installations at ports, borders, and within major cities. The article details the layered approach to detection, from initial alerts by basic sensors to confirmation and identification by specialized teams with advanced equipment. While the technology has advanced significantly since programs began after 9/11, challenges remain, including false alarms from naturally occurring radioactive materials and the sheer difficulty of intercepting a well-shielded source. The piece also explores the privacy implications of such widespread monitoring and the ongoing efforts to improve sensor sensitivity and data analysis. Read the full article at: https://www.wired.com/story/radiation-detection-systems-are-quietly-running-in-the-background-all-around-you/