ates , la 7. e a . a Pksonnel asin n Oli oa ‘ : A arRemmeeo sereace = a “verre ao AAATEORSE Oe R O Nemcoer cnnmI He PRET Mg. 3.7 . Counting Equipment in Laboratory Trailer Every sample was counted for a total of 10,000 counts or for a total counting time of 30 min, whichever occurred first. The former provided for a 0 95 error of 2 per cent (1.e., a 95 per cent probability of beingwithin 2 per cent of the true counting rate), but a time restriction was uccessory because of the work load. The background was continuously monitored with a General Radio count rate meter to indicate any severe variations in the background which would invalidate the counting done at that time, Counting rates in excess of 5000 c/n were corrected for coincidence lors, Seances of each fission product of interest were separated from a sample of U 35 irradiated with thernal neutrons in the Brookhaven reactor, These standards were used for three purposes: 1, Cross-calibration of counters for each shelf position, New counters pleced in cervice later in the operation were cross~ calibrated by means of fission products separated from ths fallout Gamples, 2. Ratios for the standardization of Revalues, (R-values are obtained by dividing the observed ratio of tro nuclides in a shot sample, corrected to zero time. by the activitv ratio of the sane two nuclides for thermal neutron fission of U235 counted under the Seme conditions.) 25 SECRET ~ RESTRICTED DATA