Fear that "terrorists" might set off a dirty bomb prompted US authorities to raise the country's level of alert to "orange" or high, a US newspaper said. Based more on experts' belief that al-Qaeda might attempt to set off a dirty bomb during the end-of-year celebrations than real information, the Department of Energy sent scores of nuclear scientists with detection equipment to five major cities, The Washington Post reported. The scientists were disguised as normal citizens and their radiation detection equipment placed inside luggage, brief cases or golf bags, officials involved in the emergency effort told the daily. Beginning on...