UNCLASSIFIED <SEEGRET @1175-AEC ~30-53 - 25 = where D = the disintegration rate of the sample in dpm I = the counting rate of the bare sample G «= the geometry factor = 2.50 L «= thickness of air between sample and counter + thickness of counter wall (sum = 2.70 me/em) & = L = | thickness of the sample in ng/om™ . 5 zs » where ~+/o is the half thickiess value of the activity in mg/cm“, the following results were obtained: kL kb p(y”) p(sr}| Strontium Sample 60.9 17.3 658 11, 320 Neodymium Sample 15.1 192 10,970 7 11,628 11,767 A very satisfactory agreement between the disintegration rateBb sr” was obtained. of y* and The recovery of the y* activity from the solution is seen to be 94% and the percentage of sr” carried over in the neodymium] precipitate &@s contamination is seen to be 3.8%. C. Counting technigue The absolute radioactivity measurements in the Chicago laborafories have been made with cylindrical thin-wall flow counters. These are shidlded with several inches of iron and with anti-coincidence counters. pmhoazt SEoRe UNCLASPIFIED LANL