The NBS holder consists of a bakelite container with an 8.25-mm wall thickness covered with a 1.07-mm layer of tin and a 0.3-mm layer of lead. The thickness of the bakelite was experimentally determined to produce electron equilibrium (Reference 49). The lead and tin layers act aS filters, which suppress lower energy components sufficiently to obtain a linear response similar to the GITR (linear above approximately 100 kev). In the energy range from 115 kev to 2 Mev, this film pack is considered accurate to +20 percent (Refefences 63 and 64) for the film emulsions tested. Twoof the five emulsions (Dupont 834 and 1293) had not been extensively tested, but were expected to fall within the same range of accuracy. Two film packets were placed inside the NBS holder, one packet containing Dupont emulsions 502, 834, and 1290, which provided a combined range of 0.2 to 2,000 r, anda second containing Eastman emulsions SQ-112 and 548-0 de, which provided a combined range of 10 to 100,000 r. Latent image fading was counteracted by making film calibration runs at shot time for each shot. Approximately 20 of the film packs described were placed in hoiders 3 feet above the deck aboard each of the target ships (Figures 1.12 through 1.14). One film pack was taped to each coracle tripod at a height of 3 feet; another was mounted in an 8-inch-diameter Styrafoam float identical to that used on the FFP’s and streamed 10 feet behind each coracle (Figure 1.2). The remainder of the film packs were placed in the array as either anchored or free-floating FFP’s (Figure 2.6). The FFP’s were of three different types, all of which represented minor modifications of the same basic deSign. In all types, an 8-inch-diameter Styrafoam float 2 inches thick and faced with two sheets of 10-gage aluminum held the pack. This small float was designed so that the film pack was supported horizontally just at the water surface and was connected by means of a 10-foot wire to a second 3-foot-square Styrafoam float, called the FFP identifier, whose sole purpose was to aid aerial spotting and identification. This basic unit was variously modified as follows: (1) a free-floating type, in which a stand-. ard 2,.5-foot canvas drogue was attached to the identifier by 50 feet of line; (2) a self-anchoring type, in which a 2.5-pound Danforth anchor was attached to the identifier by means of a ball of light twine mounted in a cardboard ice-cream carton to prevent fouling as the line payed out; and (3) a second anchored type, requiring installation by a surface craft in which the same 2.5pound Danforth was used with '/.-inch cable. Both the free-floating and the self-anchoring ° types were rigged so that they could be dropped from aircraft. All components were gathered into a compact package, which was firmly held together by a string harness containing a soluble link. Within 30 seconds after striking the water, this soluble link dissolved, thus releasing the harness and allowing either the anchor to drop or the drogue to set itself. The FFP’s were specifically designed to keep unit cost to a minimum (approximately $30.00 each). 2.2.6 Supplementary Fallout Collectors. at a few locations in the target array. A number of supplementary collectors were used These collectors included an OCC, an AOC, an AFI, and an FS. The OCC and the AOC arebriefly described together, since the latter is simply a mounted collection tray of the forme:. Both devices have been fully described in previous reports (Reference 33). In essence, the OCC is a large splashproof box, 27 by 53 inches by 5 inches high, weighing approximately 100 pounds and possessing a Sliding lid (Figures 1.15, 1.16, and 2.7}. The instrument is designed to withstand peak air pressures of 3.5 psi and will open with a 200- pound weight placed on the sliding lid. The sliding lidis moved ona roller track by a pneumatic cylinder using air at 60 psi and actuated by solenoid valves upon receipt of a signal. When sampling, the collecting tray is raised uy inch above the top of the collector to reduce Shadowbias. The device was actuated by a signal from the platform control box and remained in the open position until receipt of a closing signal. The alumimum collecting tray is approximately 18 by 21 inches by 2 inches deep, weighs 6 Pounds empty, and is used both in the OCC and as an AOC. The tray was lined with a preformed polyethylene liner and contained an insert consisting of four sections of aluminum hexcell coated & 60