50 40 30 20 . Relaxation Length, — 1/a (em) o . ® 5 & $l? 5 QO ws oOo}; S = a Pe 4 [ance h=7.4m +- 3 3 P, = 1.5 g/cm ; 1 (M/P}, = 0.333 em?/g 0 1 2 3 4 5 6 7 8 9 10 SOIL DEPTH, Z (CM) FIGURE 3-4. CONVERSION FACTORS FOR 241am GIVING AVERAGE CONCENTRATION IN THE TOP Z CM AS A FUNCTION OF DEPTH DISTRIBUTION. Detector Efficiency The in situ conversion factor is directly proportional to the detector efficiency, as shown in Equation (8). Since the conversion factor used in the field program for 241 Am assumed a detector efficiency of 19.0 eps Y/em4 = sec) , it was mandatory to correct the data for detectors whose efficiency differed from this value. Table 3-1 shows the original values obtained for the detector efficiency for each of the six detectors which were used at Enewetak. 95