Newly published data from the Semipalatinsk Nuclear Test Site, the Soviet Union’s primary nuclear weapons testing ground during the Cold War, can help today’s atomic detectives fine-tune their monitoring of nuclear explosions around the world, according to new research. The treasure trove of data from Semipalatinsk are especially important in light of the fact that only three nuclear tests — back-to-back tests in India and Pakistan in 1998 and a 2006 test in North Korea — have been conducted since the Comprehensive Nuclear Test Ban Treaty of 1996.