SIZE DISTRIBUTIONS OF RADIOACTIVE AEROSOLS 163 Table 3— RADIOACTIVITY DATA FOR 1962 IMPACTOR-- FILTER COLLECTIONS Sampling-altitude Concentration on flight date, dis/min per cubic meter (S.T.P.) Sr M0Rg Tota! beta* concentration on counting date, counts/min x G/m° (S.T.P.) interval, km Fraction UC 9.1—14.4 Stage 1 Stage 2 Filter Total 10.340.2 24743 29.8 + 0.5 287 +3 1.53 40.75 9.59 +0.49 1.17 40.22 12.3+6.9 <0.3 0.959 + 0.217 <2.0 2,121.3 88.6 + 0.4 1706 + 8 401 +2 2196 +8 14.4-—21.3 , Stage lL Stage 2 Filter Total 5.30 + 0.76 1570410 262 + 2 1840 +10 3.78 41.67 42.024.7 6.47+0.29 562.345.6 <1 27.3 41.5 <5.0 30.3 + 4,5 82,5 + 0.4 12800 + 100 1750 + 10 14600 + 100 21.3~ 27.4 Stage 1 1.63 + 0.42 0.53 + 0.30 Filter Total 45.0+20.9 228 +3 24.044.6 37 +6 3.8+42.1 1770 +12 Stage 1 Stage 2 Filter Total 1.641.2 10.041.2 8.60+1.2 20 +2 <3 <1 2.1 21.0 4.1 + 3.0 Stage 1 Stage 2 Filter Total 8,82 + 0.21 66.7+0.4 2.50 + 0.19 78.0205 0.16 + 0.11 2.38 + 0.25 0.13 + 0.06 2.7 + 0,3 374 + 2 536 +4 17.4 20.1 927 +4 15.2-—21.3 Stage 1 Stage 2 Filter Total 18.520.5 406 +5 174 +2 599 +5 <0.4 13.1 + 3.2 4.41 + 0.77 17.5 + 3.3 732 +5 3850 + 21 2530 + 10 7110 + 24 21.3— 27.4 Stage Ll Stage 2 Filter Total 10.541.3 21.2 41.3 20.0 +1.7 51.7 + 2.5 <0.6 3.40 40.13 1.7 41.0 65.1 41.0 34.3 + 1,2 83.8 41.5 39,3 + 0.3 157 +2 27.4—29.6 Stage 1 Stage 2 Filter Total 6.43 + 2.07 11.521.9 6.54 + 1.53 24.543.2 1.5 +1.1 <1 «<l 2.5 42.1 0.907 + 0.193 14.3 + 0.6 2.83 + 0.61 18.0 + 0.9 Mar, 16, 1962 Stage 2 27.4-— 29.8 181+ 3 12.8+4.1 <24 12.0 + 0.4 2610 + 15 4390 +19 6.05 34.3 27.2 67.6 + + + + 0.43 1,1 1.8 2.2 Sept. 25, 1962 — 9,1-15.2 *Beta-counting interval for the Mar. 16, 1962, collection is Apr. ] to 18, 1962, and for the Sept. 25, 1962, collection is Oct. 9 to 25, 1962. The assigned errors represent one standard deviation, 1 a , in the ob- served net counting rates as well as an estimate of the accuracy in resolving beta-particle absorption or decay curves. Whenever observed counting rates were close to detector background levels, gross counting rates were increased by 2 a, and upper limits were calculated. The low concentrations and small sample volumes prevented extensive 40Ba analyses and, in some fractions, **Mn determinations. It can be noted from the data that the general reliability of the values for individual radionuclides increases in the order M0 Ba, Sr, “un, Mace, and *Zr, which is approximately the order of increasing observed activity.