sare CHAPTER 4 SAMPLE ANALYSES AND DATA REDUCTION 4-1 SAMPLE ANALYSIS Besic analysis consistec of gamma ccuntineg thoce samples collected for the determination of fallout contcurs ond measuring the falleut particle size distribution end the anrarent density of the rnarticles. 4.1.1 Counting Technique Two instruments were emnloved in counting semnles. The 47 7amra fonization chamber was used where conversion of measured activities to gamma field intensities was desirec. The camme scinti}letion counter was used where relative levels of activity were desired. The 47 ramma fonization chamber and its calilration ere identicei io that deserited in -ECD-2367, This instrument consists of a pressurize? ion chamber, vibrating reed electrometer, and a Brown millivolt recorder. The chamrer is filled with arson st a pressure of 600 psig and onerstes at a collection potential of 600 v. For low beckercund the assembly is lead-shielded. Samples are lowered into the center of the chamter. Bectise the position of the source meterial is not. critical, activities of larre volumes of either licuid or solic samples cer. be measured. The gamma ionization chanter readings were converted arbitrarily from milli- volts to mr/hr in order that all readircs taken on fallcut te excressed on a conventional basis. A relaticnship between the chanher readings in mv and a calibrated AN/PDR-T1B Survey meter was determined. Corresponeing readings of ‘5 randomly chosen sarvles from Shot 1 were taken by both instruments. Tne eoustion of the resulting linear vlot showed mr/or = —0V__, 519 “ With this reletionship determined from ~arples of hich Jevels of activity conversion of samnies of low activity, accurately messured in the 47 tonchanl er, readings coulc then be reliatly converted to equivalent mr/hr. The scintillation counter Veonsi sts of a detector assembly and Li