For the Conrad I detector, n = -2, and: ar = 226t r t (2.7) In practice, at high-pulse-repetition rates, a number of pulses N over a period T were used to read out the data. Hence, from cquation 2.5: Ar . (Nt + At? - (Ney? F int Ar . (T+ At)? - (TP r ph (2.8) nAt T Where: At nowincludes all errors in reading the time interval T. The time-base error for the Conrad recorders was + 0.069 percent; therefore, the readout error was negligible, and the errors of the Conrad I system (of the order of 10 percent) could be attributed to the detector itself. For the Gustave I system, n = -1, and: Ar . -At (2.9) rT Hence the Gustave 1 system error was essentially that of the detector (the time-base error £0.02 percent), and was of the order of 10 percent. 2.4 BEACH-BALL-KADIATION-DETECTOR-TELEMETER UNIT To attain the objective of measuring the residual-exposurerate on the crater of a land-surfaceburst, a droppable radiavion-detector-telemeter unit was devised. A Gustuve I detector system was connected to key a 1, -watt VHF transmitter that had been constructed in the field. The detector and transmitter were mounted in a polyethylene bottle suspended at the center of an air-inflated, 5-foot, plastic beach ball. The beach ball was attached to a 27-pound lead brick by means of a 6-foot line. This made it possible to drop the system from a helicopter move accurately with a minimum of impact shock to the instrumentation. The lead brick hit the ground first and allowed the beach ball to slow down over the 6-foot distance before hitting the ground. In ad- dition, the beach ball itself acted as a good impact absorber. Once the beach ball was released, the helicopter could go a short distance away and orbit in a radiologically safe region, while receiving the data transmitted from the beach-ball unit. 26