: Dm a yeta LmNONARI ERROR ES os Perey ne “. WAOALEYJt SRCSie | beee ene Alte mers tet sas er mere een ame me ae oe 3.6 CALIBRATION Calibration consisted, essentially, i: termining electron-beam: deflection of the cathoderay tube corresponding to material density along the beta path. Since the deflection sensitivity of the cathode-ray tude was constant, calibration could also be done by measuring the deflection voltages corresponding to known values of material density along the beta path. In the field, calibration was accomplished by: 1. Recording on film, just prior to installing each instrument station, electron-beam deflections corresponding to several known values of deflection voltages. 2. Recording the elect: on-beam deflections corresponding to known thicknesses of two aluminum foils over the receiver. The aluminum foils are released one at a time between H-5 sec and zero time. Thus, a calibration trace obtained just prior to shot time appears on the samefilm with the density record. cee pe The information from field calibration when checked against laboratory measurements of deflection voltages and be~m deflections corresponding to known values of material density in the beta path enables one to convert the record of beam detlection into material density. The calibration foll-release circuit is shown in Fig. 3.8. 3.7 INSTKUMENT STATIONS He Ae ene Whoa s.* VORPOeEIR EROMEER de om Seetaes Densitometers were located at four stations: Station No. 690.01 690.02 690.03 690.04 Site Distance from ground zero,ft Engebi Kirinian 19,166 23,219 Aomoa 47,897 Bokonaarappu $0,501 A detail drawing of the instrument staiion is given in Fig. 3.9. 23 RESTRICTED pata SECURITY INFORMATION

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