[en] The Department of Energy (DOE) National Nuclear Security Administration (NNSA) is responsible for maintaining national-level radiological emergency response assets and for deploying those assets in the event of a radiological accident or incident. NNSA's emergency response assets include the Aerial Measuring System (AMS) and Search Response Team (SRT) operated by the Remote Sensing Laboratory (RSL) located at Nellis Air Force Base, Las Vegas, Nevada and Andrews Air Force Base in Suitland, Maryland. The AMS mission is to provide a rapid response to radiological emergencies with helicopters and fixed-wing aircraft equipped to detect and measure radioactive material on the ground. The acquired data are stored and used to produce maps of radiation exposure and activity concentration per unit area. AMS also conducts surveys to create radiological baselines of major cities and nuclear facilities throughout the country. The SRT's Crisis Response (CR) mission is to provide scientific, technical, and operational support for NNSA-directed search activities involving radiological search and identification, through both field deployments and home team and reachback support. 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-inch x 4-inch x 16-inch 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). The ground-level data were collected by the RSL Mobile Search System (MSS), to detect gamma-rays and an array of He-3 filled proportional counters for detecting neutrons. A Global Positioning System (GPS) antenna and a receiver were included to provide time and location information for real-time displays and post-survey analysis. The embedded computer in the system has real-time analysis functions which provide prompt alerts when elevated levels of radioactivity have been measured. While the system is operating, it writes the spectra from the gamma-ray detectors, counts from the He-3 array, and GPS position and time every second to a removable memory card. The data can be transferred from the memory card to other computers with more powerful analysis programs where they may be examined for the presence of man-made radioactive materials. The MSS was driven around the LVMS and through the adjacent business park on February 23, 2009