tained by F-84 and B~36 aircraft penetrating the cloud to produce 4 response tu rate of change of pressure down to very-low frequencies. ° sitivity was ap- proximately 50 mm/(dyne/cm*®) Angus recorder operating at 0.7 The AFCRC operated modiffe developed by NEL from each detonation. an Esterline- Air Weather Service WB-29 aircraft equipped with particulate and gas-sumpling n/min. T-21~B equipment devices collected samples at remcte distances from the nuclear detonation Five F-84G aircraft utilized the method of snap gas-sampling. This consisted of an exterior stainless - Tape speeds and sensitivities were approximately the same as those used by NEL. The Air Weather Service (AWS) operated crossed- steel probe in the nose of the aircraft that fed into a deflated polyethelene bag. Sampl«s were taken by activating a valve andfilling the ; olyethelene bag by ram pressure. loop goniometers at distant stations to record azi- rnuths. These were similar to their standard sferics low-frequency (10-kc) narrow-band (about 0.5-kc) direction-finding stations used for locating thunder- Ten F-84G aircraft were cq..ipped with a dual elec- trical compressor system feeding into two 500-in® stormareas as an aid to weather forecasting. The ag operational stations had a slightly wider compression cylinders (3,000 psi). All of the air sampled was bled from an intermediate stage of the bandwidth (8 to 12 ke). Distant stations for the most part utilized locafions aready in use by NBS, DRL, AWS, or A axial compressor of the aircraft and fed into the dual compressors—-the squeegee method. Operation Castle provided the first full-scale operational test of this system. In addition, several B-36 aircraft were equipped with the squeegee system; for these, lusofar as possible, sites were chosen on east-west anc norta-souti orientations in an attempt to get some idea of differences due to a daylight path, a uark path, and auroral-zone transmission. Some distant stations were located in proximity to the intake air was bled from the upstream side of the large cabin pressurization filter and fed through com- stations transmitting low-frequency carriers. In order to avoid interfe rence from these stations, their cooperaticn was enlisted and they were shut down at ~ pressors into 900-in’ (3,900 psi) cylinders. critical times. samples and a B-31 gas-sampling device for gaseous debris. Project 7.2 9 Longer-range samples were obtained using WB-29 aircraft with associated C-1 foils for particulate “Detection of Airborne Low-Frequency The collection of all close~in particulate samples was under the technical direction of the Los Alamos Sounafrom Nuclear Explosions” (WT-931), A G. 8B Otmsted, Project Otficer. Scientific Laboratory (LASL); the collection of gas samples was supervised by AFOAT-1. The Umversity Measurements of tie airborne low-frequency sound from the Castle detonations were made at fifteen re- of California Radiation Laboratory (UCRL) was responsible for gay separation and analyses of some samples at the test site. mcte locations at a variety of distances and directions from the Eniwetok Proving Ground to study the relathon between signal characteristics and the energy Instrumentation, techniques, and procedures in the processing, separation, and assay of the nuclear released over a range of yields up to 15 Mt. Both standard and very-low-frequency sound- particulate and gaseous debris are included in detailed LASL and UCRL reports. Close-in gas samples were collected at altitudes recording equipment responsive to smal! atmospheric pres-ure variations in the frequency range from 9.0uz to 1 eps were employed in the range of 35,000 to 50,000 feet MSL. Project 7.4 “Calibration Analysis ofClase -in Atomic Device Debris” (WT-932), AFi : D. L. Northrop, Project Officer. Gaseous debris sample sizes collected varied from 107'* to 107"? bomb fructions. Representative sections of each test cloud were sampled, but due to extreme The work of this project was a continuation of a oregram cstablished to monitor all U. S. nuclear cloud heights obtained on high-yield detonations, only tbe lower portions of these clouds were sampled. detonations, in order to determine calibration reference points for the analysis of airborne nuclear Long-range samples were collected from approximately sea level to 20,000 feet. debris. These data were obtained by the application of chemical, radiochemical, physical, and nuclear analyses to the debris collected by specialized sampling devices. The calibration daca were further ©x- PROGRAM 9: TECHNICAL PHOTOGRAPHY tonded by making similar measurements on nuclear Project 9.1 “Cloud Photography” (WT-933), debris collected at great distances from the detona- Edgerton, Germeshausen and Grier, Inc., Jack G. James, Lt Col, USAF, Project Officer. tion Nucltear-debris samples close-in to the detonation were obtained utilizing sampling devices on F-84, WB-29, and B-26 aircraft. Similarly equipped WB-29 aircraft operated out of Hawaii for the long-range calibration samples. Close~in particulate and gaseous samples were ob- 117 Project 9.1 was established for the purpose of recording photographically cloud formation phenomena that would satisfactorily supply data for use in studying the aircraft delivery problem and correlation of fallout studies in relation to cloud drift. The technical aerial photography was conducted by Lookout