elose-in and long-range--~are of such magnitude and variation that it is not practical to itemize these in this report. Chemical procedures for separation and assay of the radioactive isotopes, specialized separation equipment, counting equipment, and other instruments are included in the detailed reports by agencies responsible for the separation and assay of these isotopes; the most pertinent are References 3, 4, 5, 13, 14, 15, 16, and 17. 2.2 OPERATIONAL PROCEDURES 2.2.1 Close-InSampling. Close~in gas samples were collected during Castle at altitudes of 35,000 to 52,000 feet MSL. Sampling aircraft were directed into the nuclear cloud generally no sooner than two hours sub- sequent to the detonation and followed each cloud for approximately 5 to 7 hours, obtaining samples. To ensure no cross contamination of sampling equipment between shots, control samples were taken before and after a washdown of the sampling equipment. Gaseous-debris sample sizes collected varied from 1075 to 10°!’ bomb fraction. Duration of sample collection time varied from approximately 40 to 60 minutes in the case of the Squeegee method to less than 1 minute by the snap~sampling method. Squeegee gas samples in the high-pressure spheres were removed from the aircraft upon return to the ground and crated for shipment to the separation laboratories. Transfer of snap samples from the polyethylene bag to a G-l cylinder was required prior to shipment. Representative sections of each test could were sampled, but because of extreme cloud heights attained, sampling was conducted in only the lower portions of the cloud for the high-yield detonations. 2.2.2 Long-Range Samples. long-range samples were collected by WB-29 aircraft steging out of Hickam Field, Guam, and McClellan Air Force Base (California). Samples were collected from approximately sea level to 20,000 feet altitude. Gas samples were obtained with B-3l collection equipment, which consisted of a Quincy compressor feeding into 5 J~l gas~ storage cylinders. The average sample size collected was approximately 500 ft3. In addition, these aircraft were equipped with C-1 particulate samplers employing IPC paper as the filter mediun. 2.3 ANALYTICAL PROCEDURES 223.1 Radiochemical: Particulate. Particulate nuclear debris col- lected by the filter-paper technique was radiochemically analyzed in order to provide the following information: l. Sufficient fission-product data to establish a fission-yield Curve with emphasis on studying the trough elements, peak elements, and those on the right wing of the fission-yield curve. About 30 fission Products, from Zn™ through Tb'®!, were chemically separated from the 8ross sample and assayed. he same sample. 2. These were then referred to Mo*? measured in Uranium and plutonium isotopic abundances were determined by 13