and half width of peak measurements of secondary reactions. both primary and secondary coverage was provided. To accomplish this, four alpha stations were activated. When required, The complexity of measuring systems varied from experiment to experiment, depending on specific requirements for a given device. Except for surface shots Cactus, Koa, Quince, and Fig, all devices on which alpha was measured were detonated from barge locations. On seven tests, detectors were mounted at zero site and recorded the complete reaction history. To obtain at the detectors a signal representative of the neutron signal, it was advisable to limit the emerging gammas by an aperture near the device. In addition, collimation at the detectors was accomplished by means of pipes which extended through the thickness of the blockhouse wall at the alpha station. Inside the detector room were adjustable baffle walls contain- ing collimating holes which were spaced for alignment. In some cases at- tenuators were provided to reduce the gamma signal. Three basic oscilloscope systems were employed for recording the alpha signal: a 100-ohm three scope system, a 100~ohm two scope system, and a 120-ohm two scope system. Three types of presentation were recorded on the scope faces: Rossi, linear, and creep-Rossi. Having initially planned on nine LASL experiments, TU-5 was hard pressed in extending coverage to the increased program. Reaction history measurements were made on a total of 19 shots, 14 LASL and 5 UCRL shots. Oscilloscope traces were analyzed by means of precision comparators on each shot. These data were then reported on an IBM 704 EDPM computer. A shot report was issued, usually within 3 days following the event. General Administration. A total of 320 Edgerton, Germeshausen, & Grier employees contributed to the successful completion of TU-~5's effort in the Forward Area. Equipment installation began in early February, and a peak working force of 149 men was in the field on about the first of May. The average stay in the Forward Area was 8 weeks. A total of 180 tons of equipment was shipped to the Forward Area. Central warehousing was maintained on Parry Island in approximately 1200 sq ft of existing buildings in the old CMR compound. The last TU-5 crews departed from the Forward Area on September 1. Johnston Island Activities. The primary objective of TU-5 at Johnston Island was to supply experimenters with an accurate sequence of timing signals, related to burst time, for the purpose of starting and stopping their equipment on both the Teak and Orange events. Other objectives were (1) to determine the time of burst with respect to WWVH, and (2) to provide a system of radio links to experimental stations over which voice-time announcements synchronized to the timing system could be transmitted. Early in 1957 preliminary planning for a timing system to meet the special requirements of Teak and Orange was begun. As planning progressed, it became apparent that the regular sequence timing system planned for the surface shots on Hardtack would not meet the special requirements of these shots. A new sequence timing system patterned after the air drop system used on Plumbbob for the John event was developed in the EG&G Boston laboratory. This system was integrated into the Bikini hardwire timing sys- tem for Hardtack. The timing system was assembled and operationally tested under simulated field conditions in Boston prior to its shipment to the Forward Area. In February 1958 the equipment was shipped to the Forward Area and installed 124