a searchlight reflector, with the lighting element replaced with a photocell; (2) cathode follower; (3) preamplifier, Hewelett-Packard Type 4SOa (not used in the airplane); (4) cathode ray tube with associated amplifiers; two circuits were used, one set at a gain of about 15 times the other in order to provide a wide latitude scale for recording the varying-amplitude light pulses; (5) strip film camera for photographing both ‘scope faces; and (6) associate equipment such as power supplies, communications radios, standard light pulse generator for camera speed calibration frequency meter. Figure 1, taken from Reference 3, is a block diagram of a typical remote static». As during the Snapper tests, the time constanta of the Ivy equipment were set to give maximum discriminatiur against background; so times to minimum, and hence yield calculations, from the Ivy data, are not applicable. RESULTS AND DISCUSSION Mike time of detonation, as reported by reception of the electromagnetic signal by the National Bureau of Standards (NBS) under Project 7.1, was 31 October at 1914: 59.204Z. As stated above under OPERATIONS, the Johnaton Island and Kwajalein Island camera runs were started by the AFSAL five-seconds-until-detonation signal at 1914: 59 Z. Starting by stop-watch only 0.2 second before the actual detonation, it cannot be stated whether or not the equipmmnt was operating at detonation time; in any case, there is no indic&tion of a signal at either station. The camera run on the airplane was started at 1914: 55 Z, so it is likely that the equipment was in operation at detonation time, but no ‘ bomb trace can be located on the film. As indicated above for King shot on 15 November 1952 at Kwajalein Island, the film run was started at about 2330: 042, according to the AFSAL five-second-alert signal; however, the shot actually went off at 2329: 59. 789Z as determined by the reception of the electromagnetic signal. It is apparent that the equipment was started too late. At Johnsto’ Island the run was commenced sometime between the scheduled minus-fivesecond carting time and the actual five-seconds-until-detonation signal which occurred a>out four seconds after the half hour. It cannot be stated whether or not the equipment was started before detonation time; there is no signal discernible on the record. The bhangmeter equipmentin the C-47 plane was over Kwajalein at 12,000-foct altitude, and waa stated by allowing for time-of-fall, about 55 seconds, after hearing the bombsaway broadcast signal. During this experiment, a signal from the bomb was recorded; it is reproduced in Figure 2. The absorption can be calculated from the signal amplitude on the trace shown in Figure 2. The signal on 16-mm [lm was 0.016 film-inch on the low gain trace and off scale on the high gain trace; the sensitivity ratio between the two is 18.5. e Equivalent signal 0.016 x 18.5 = 0.296 film-inch Equivalent voltage Photocell current = 0.083 ua current x cell sensiuvity irradiance = soos cell x collector gain pwatt * = 0-083 ya x oto ia 5.28 om? “50 = 0.083 x 4.07 » watte/cm? = 3374 watts/m? - 3 i 12 sake £0 PLA READ Me = 0.415 volts