b'FeatureAirborne radiometrics over Maralinga - call for a new survey rectangular blocks measuring 10.2 cms x 10.2 cms x 40.33 cms. The volume of NaI(Tl) crystal was 33.56 litres with a surface area of 1.482 m2. The equipment was mounted inside a Cessna 206 aircraft. Each of the eight detectors had its own photomultiplierSurveyingThe \x1cying height was 40 m and the line spacing was 80 m. The direction was east west. The airspeed was 70 m/s. 256 channels were recorded every second.ProcessingWith access to the EG&G report WGC decided to use identical signal windows (Figure 6).The Cs-137 window selected for processing was 590 keV to734keV and the window at 974 keV to1550 keV was selected to capture Co-60 and Eu-152.Am-241 was not detected as theFigure 12. Ratio of caesium/potassium WGC 1992. Raw counts in the 590-734 keV window were divided by the counts in the 1370-1570 keV window. spectrum measured began at 300 keV and was much higher2Concentration values for caesium 137 in Bq/mare indicated with values than the Am-241 photopeak at 59.5 keV. calculated from those observed in 1987. Image overlays SPOT panchromatic satellite image.ResultsThe caesium 137 window (590 -734 keV) contained only one strong peak. The counts as measured were divided by those captured in the K40 window (1370-1570 keV) to achieve a caesium/potassium ratio. The actual concentration value for caesium was calculated from the observed values obtained by EG&G in 1987 with half-life calculations for 1992 applied (Figure12).The neutron activation products cobalt 60 and europium 152 were processed using a broad window (974-1550 keV) that captured the photo peaks of both elements. The results were presented in the original cps which ranged up to 16 000 (Figure13).The images obtained were draped over topography from a SPOT satellite image showing roads, vegetation and sand dunes.The Fugro 2005 airborne surveyThe Pace One Tree survey was \x1cown by Fugro Airborne Surveys for Geoscience Australia Figure 13. Image of neutron activation elements products cobalt and europium presented as an aggregate from the 1992 WGC survey. The nuclear test sites are labelled. The chosen window (974-1550 keV) contains \x1dve photo-Equipment peaks of Eu-152, two of Co-60 and one of K-40. The activity of these elements is measured in counts per second. The background topography is a monochrome Fugro collected data from 0-3000 keV in 256 channels. TheSPOT satellite image. Roads, bushes and sand dunes are visible.spectrometer was an Exploranium GR 820. A data acquisition system interrogated two crystal packs each containing four rectangular blocks measuring 10.2 cm x 10.2 cm x 40.33 cm. The55, 56 & 57) was chosen to capture the Cs-137 peak at 0.662 keV volume of NaI(Tl) crystal was 33.56 l with a surface area of 1.482m2.divided by a raw potassium window (1.370 MeV to 1.570Mev) The equipment was mounted inside an Aero-Commander 500SFor caesium activity concentration a half-life decay of aircraft. Each of the eight detectors had its own photomultiplier. 30.17years from the 1987 values to 2005 was applied (Table3). Surveying The data was presented as an image (Figure 14).The \x1cying height was 80 m and the line spacing was 400 m.The Thomson Aviation 2018 airborne survey Theaircraft speed was 70 m/s. The Thomson Aviation Gawler Craton Survey was \x1cown for The survey contained 36 141 line km \x1cown as one area overGeoscience Australia.51 \x1cights. The area lies within the Ooldea, Nullarbor, Maurice, Barton and Tallaringa 1:250 000 map sheets (Fugro 2005). EquipmentProcessing Thomson Aviation collected data from 0-3000 keV in 256 channels. The spectrometer consisted of two linked RSX 4 An area over Maralinga was excised from the survey and asystems. The data acquisition system interrogated two crystal window from 0.600 keV to 0.700 keV (raw spectrum channelspacks each containing four rectangular blocks measuring APRIL 2024PREVIEW 53'