RSL-Nellis Analysis of Radiological Survey Data from the Las Vegas Motor Speedway

摘要

The AMS radiological mapping and SRT CR emergency response teams from the Remote Sensing Laboratory-Nellis (RSL-N) supported safety and security activities at a NASCAR race at the Las Vegas Motor Speedway (LVMS) on February 27-March 1, 2009. In support of this event, and for proficiency training, these teams carried out aerial and ground surveys of the area. The aerial radiological survey of the LVMS was conducted on February 17, 2009, and the CR ground survey was performed on February 23, 2009. RSL-N operations and appropriate law enforcement agencies selected this area as a suitable location to exercise AMS and CR capabilities for mapping environmental radiation and searching for man-made radioactive sources. The aerial surveys covered approximately 11 square miles. The survey required a 2.5-hour flight, performed at an altitude of 150 ft above ground level (AGL) at a line spacing of 300 ft. Water line and test line flights were conducted over the Lake Mead and Government Wash areas to determine the non-terrestrial background contributed by aircraft, radon, and cosmic activity, and to determine the altitude-dependent mass attenuation correction for air. The aerial data were collected by the AMS data acquisition system (REDAR V) using an array of twelve 2' OE 4' OE 16' sodium iodide (NaI) detectors flown on-board a twin-engine Bell 412 helicopter. Gamma energy spectral data were collected second-by-second over the survey area. This spectral data allows the system to distinguish between natural terrestrial background contributions and man-made radioisotope contributions. Spectral data can also be used to identify specific man-made radioactive isotopes. Data geo-locations were determined with a Real-Time Differential Global Positioning System (RDGPS).