2.1.8 Program 16, Gamma Intensities at Late Times (a) Objectives 1. To determine the number of neutrons escaping the case for the Castle devices. 2. To determine the numberof fission gammas coming fromthe fireball a few tenths of a secord after the detonation, and fromthis to determine the fission yield. (b) Technique To measure gamma rays as a function of time at various distances from zero. Interpretation of the early records is complicated and involves difficult hydrodynamic and neutror.-diffusion calealstions. After shock arrival most of the air between the source and tho detector has been rene 4. This allows a reiatively simple esti..: ‘2 of fission yield by mea. vving fission areas. , (c) Residts Results of measurements of neutrons and fission yield are given in Table 2.5, together with neutron measurements by threshold detectors. 2.1.9 Program 17, Microbarographic Measurements (a) Objective To use the large detonaticns of the Castle series to study the upper atmosphere. (0) Technique Microbarograph recorders were placed on the USS Curtiss, Eniwetok, Kwajalein, Ponape, and in New Mexico. (c) Result Records were obtained on all shots and are presently being studied. Thee \g Yeleted 17 ee e