EZ EEREGAZILTEREDS ” ra ra i the other alkaline earths.(4) With trsicr tethmioue, a high yield of carrier strontium can be obtained, Several ecsid treatments are required and the actual number depends on the ameunt of calcium which was leached from the soil, Following the fumirg nitric acid separation, thorium, lead and any contaminating fission preducts remaining are scavenged with yttrium hydroxide, and radium and barium are removed by a barium chromate precipitation. The daughter yttrium is milked after equilibrium and beta counted as a measure of the strontium-90 activity. Absorption corrections are not necessary since the weight of the precipitate can be rigidly controlled at this point. Twenty milligrams of yttrium carrier are added just prior to milking and the standards are prepared in an identical manner. The step-wise analytical procedure is given in section 6.2 of the Appendix. Colt OGLTLE Samples are mounted on piastic cises, covered with Mylar, and the assembly secured with a plasti: rioz. The sample is clamped into position under one of three oneeinch Anton halogenefilled steel window GeM tubes (# 1007 M) which are surrounded by a guard ring (46 "pencil tubes" Anton# 315) in anticoinciderce, shielded with 3 inches of mercury and beta counted for at least one hour, FEackgrounds less than one count per minute are obtained using this counting system. (3) (i) Modification of the method reported by Willard, NoHe, and Goodspeed, Bo Wes (5) More recently, res Indus oe ENE o Chems Ans?, mang, ah (1936), NYO-h700 @ Manual of Stacti.: © tistives, LeVine, HeDo, Charlton, Loe, Greviicr, “:t., Low Background Nuclear Counting Equipment, HASL-650, liars. 25, 1)