Chapter 2 PROCEDURE 2.1 OPERATIONS Table 2.1 lists shot participation and instrumentation. The instrument stations were placed in previously prepared positions at the latest practicable time prior to each shot and were recovered postshot as soon as Rad-Safe conditions permitted. The residual stations were activated upon placement. Theic 5-day operating period aliowed for 2 days of data-recording and three 1-day shot deluys. For the surface bursts, the initial stations were activated by a minus-i-minute-timing signal for warmup, and a minus- 15-second signal to start the recorder. Shot Zuni \as an exception; only a minus~1second signal was available to start the recorder. Timing signals were necessary on the initial stations because of the limited recording time available (Cook Research Laboratory MR 33 recorders, 4 minutes; Sunborn recorders, 15 minutes). For Shot Cherokee, the recorders were nov sturted until after the device release. 2.20 INSTRUMENTATION In designing instrumentation for this proicct, there were two objectives: (1) to design instruments to best fulfill the requirements; and “2\ io design flexible instruments read~ ily adaptable to a wide variety of field ineusurements. In view of this dual objective, the instruments were designed to be compact, drift-free, reliuble, wide in dvnamic-range coverage, and low in cost. The basic circuit evolved measured disecrece increments of charge. Essentially, this cirenit could be used with any sensing element that had an output which was u knewn function oi the radiation field. Thus, the circuit was equally applicable to iun chambers, scintillation deteclors, or photo-conductive crystals. In operation, the charge on C, (Fisure 2.1) held tube T, well beyond cutoff. The output current of the sensing clement discharged C, at a rate dependent upon the radiation level. When the voltage at the grid of T; reached the grid base, T, conducted, fed a negative sig- nal to the grid of T,, and initiated a revenerative action which rapidly cut off T,. Then Cy charged to a potential equal to B-plus tess the cathode volt..ge and the grid-to-cathode drop through the diode action of the grid of T;. When Cy was completely charged, the circuit returned to its normal] condition of T, conducting ani T; cutoff. The circuit remained in this condition until C; was onee more discharged by the output of the sensing element. The output of this circuit consisted of pulses that had a repetition rate propor-~ tional to the output current of the sensing element. 2.2.1 The Residual Instrument System, Conrad I Detector. gamma-exposure rate from [nilout contamination is given by: In general, decay of the I= i,t * \ Xx it 1] =the gamma-exposure rate ut time t the gamma-exposure rate at unit time fi Where: (2.1) the decay constant (given as 1.2 for gross fission products) 18