rays per minute the reciprocal of the efficiency was employed and put on an absolute basis with the Ce~and-Zr data. For the geometry used in this work Ce gave 3.70 gamma rays per volt count per min at 145 kev and Zr 23.6 gamm rays per wilt cout per minute at 730 kev. curve shown in Fig. 3.27 was normalized to these values. 308.4 The Results The area of the photo-peaks of the various gamma rays was plotted as a function of time on semi~log paper and extrapolated back to shot time. Nigure 3.28 shows such a curve for the decay of the 1600kev gamma ray in La+4¥. The slope of the curve is in excellent agree- ment with the accepted value of the parent Bal49, The decay schemes of Bal40 ani Lal40 are known, which enabled the gamma contribution of the ether gamma rays from the 1600~kev peak to be calculated (Table 3010). a TTT a b* ” a3 “ lJ j= iw 20 = Ww = 10 0 Lt jf jit} ft l i l L py 107 PHOTO PEAK (VOLT COUNTS/MIN/GRAM OF SAMPLE) 10° Figs 3028 The La!49 1.6 Mev Photopeak as a Function of Mme The experimental results are given in Table 3.11. The results are recorded as the number of gamm rays per minute per gram of fall- outs The quoted errors represent the reproducibility of the method or the precision with which the intensity of a particular gamma ray is kmown in the sample. These errors were judged from the fit of the experimental decay points to the best straight line represented by the points. No estimate is made of the absolute accuracy of the data. However, when varying mixtures of 2r95-Nb95, Bal40_14140, and colds = Pri44 vere synthesized and analyzed by the technique, the mximum error between the actual composition and the gamma spectral analysis 82