TABLE 3.8 ~ Activity Concentration of Shot 4, How, Liquid Fallout Time After Shot Activity Concentration (c/min/ml. Chr) i- 3 3.2 x 104 3 - 5 @- 9 9 -10 10 -l 403 5.0 7.2 7.69 ll -12 3-7 x x x x 104 104 103 103 1.8 x 104 BETA ENERGY MEASUREMENTS Aluminumabsorbers, inserted between the sample and tube window very near to the tube window, were used on selected samples to determine the maximm range ard energy of the beta radiation. A plot was made of activity vs absorber thickness; sufficient absorbers were used to obtain the gamma background associated with the beta activity. A sample plot is shown in Fig. 3.23. The maximum range, R, of the beta radiation was determined by visual inspection of the point on the curve where the gamma contribution ceased to be the sole contributor to the total activity. The beta energy, E, was calculated using the relation.14/ where EB =1.85R # 0.245 (3.21) E * maximum energy in Mev R = maximum range in aluminum in mg/cm The results are presented in Table 3.9. Absorption methods for the determination of beta energies for fission product samples are subject to error due to the presence of a significant amount of gamma activity which overshadows the activity of high energy beta emitters present in the samples. Determination of the range by visual inspection of the curves when gamma backgrounds are present will yield an apparent range which is less than the actual ranges The data indicate that the apparent mximum beta energy of sev- eral Shot 1 samples increased from 1.7 Mev to 2.2 - 2.5 Mev during the period from 9 to 70 days after the shot. The Hunter~Ballou curves indioate that 9 days after fission the contributors hayine the highest energies are Lal40 1.7 Mev) and Pri44 (2.97 Mev). La contributes 12 per cent and Pri 0.3 per cent of the total activity at the time. Shot 1 absorption data taken 9 days after the shot indicate the pre- sence of Lal40, As the time after the detonation increased, the curves indicated that the contribution of Pr144 to the total activity increased (16s, 0.9 per cent and 2.4 per cent at 24 and 70 days 73