The US Domestic Nuclear Detection Office (DNDO) has terminated a seven-year effort to develop next-generation radiation monitors for screening cargo at US ports of entry. The Advanced Spectroscopic Portal (ASP) system, a sodium iodide–based monitoring system that was first proposed in 2004, failed to attain its design specifications after multiple rounds of testing and software tweaking. Conceived to be capable of discriminating nuclear materials from harmless radioactive sources that are often shipped in cargo containers, the ASP system was claimed by vendors to reduce by 80% the number of false alarms that occur with today’s polyvinyl toluene (PVT) portal monitors. Unlike the scintillator-based PVT, ASP technology allows the specific isotopic source of radiation to be identified by its characteristic emission spectrum (see PHYSICS TODAY, June 2010, page 22).
Warren Stern, DNDO director, announced ASP’s termination in testimony to the House Committee on Homeland Security on 26 July. Stern said...
