Signal Detection in Radiation Portal Monitoring Data

• Activity Number: 98
• Type: Topic Contributed
• Date/Time: Monday, August 7, 2006 : 8:30 AM to 10:20 AM
• Sponsor: Section on Statisticians in Defense and National Security
• Author(s): Tom Burr*+ and Jim Gattiker and George Tompkins
• Companies: Los Alamos National Laboratory and Los Alamos National Laboratory and Los Alamos National Laboratory
• Keywords: radiation ; monitors ; signal ; detection ; background ; suppression

Abstract

Data from passive radiation portal monitors (RPMs) have been collected since 2002 to detect potentially harmful radioactive cargo (i.e., special nuclear material (SNM)). Detection of illicit SNM using RPMs is complicated by several factors, including the possibility of shielding the emitted radiation, drifting background and/or sensor response, variable-length vehicle scan time, cross-talk between neighboring lanes leading to either suppression or elevation of respective lanes, and vehicle shadow-shielding, which implies that vehicles with or without radioactive material will suppress the natural background. This talk will describe nuisance and statistical alarms, background suppression, energy windowing, alarm rules, and an injection study that considers the effect of five factors on SNM detection in a full, five-factor factorial experiment.