ray detected. Geometry also had an effect. Gamma measurements would only have meaning if the geometry were somewhat fixed and remained so. For this reason, measurements were made at one meter above the ground surface. Due to the shielding from the case and the canning of the crystal, there is a definite cut-off gamma energy of 100 KeV, below which no gamma radiation is detected. These limitaticns are recognized and will be accounted for in any interpretation. The soils data will provide information on what radionuclides are present and their effect on the gamma exposure rate. The Baird-Atomic Scintillator measurements will be correlated with the soils data, TLD data, and the aerial survey data to produce meaningful results. The measurements made by the Baird-Atomic scintillator are recognized to be relative and are interpreted as such. The FIDLER probe was utilized on YVONNE for various measurements. This instrument has Sery severe limitations, which, if not recognized, can dean to gross misinterpretation of data and results. The FIDLER is a special configuration of NaI detector designed to measure plutonium con-~ tamination resulting from a nuclear weapons accident. The instrument was designed, specifically, to measure uniform plutonium contamination on the surface of a plane, normal to the cylindrical axis of the FIDLER probe without the presence of any other gamma emitters (except the associated ehlan). The probe actually detects the gamma radiation from the associated Americium-241 and the weak X-radiation produced by Plutonium-239. A discrimination circuit looks at only the related gamma energies of 60 and 17 KeV. Of course, it detects any gamma radiation at these energies, with- out regard to the actual source. In other words, it detects the 60 and 17 KeV gamma of Americium-241 and the 17 KeV X-ray of Plutonium-239. It also detects 60 and 17 KeV Compton scattering radiation present from any other