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 gamma rays per wilt count per minute at 730 kev. curve shown in Fig. 3.27 was normalized to these values. BeBe The Results The area of the photo-peaks of the various gamma rays was plot~ ted as a function of time on semi-log paper and extrapolated back to shot time. “igure kev gamma ray in La 3.28 shows such a curve for the decay of the 1600« The slope of the curve is in excellent agree- meiit with the accepted value of the parent Bal40, The decay schemes of Bal4O am Lal40 are knom, which enabled the gamma contribution of the other gamma rays from the 1600-kev peak to be calculated (Table 3010). KR T z 7 Pr oy ToT ty QO 5 “T DAYS . HALF LIFE=> !2.8 ” 0a " we 4 <20ul = “ bt 10 0 il L Loy tl 1 | 104% i | 10° PHOTO PEAK (VOLT COUNTS/MIN/GRAM OF SAMPLE) Figs 3628 The Lat49 1.6 Mev Photopeak as a Function of Name The experimental results are given in Tablo 3.11. The results are recorded as the number of gamma rays per minute per gram of fall- oute 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 Zr95-Nb95, Bal40-1al49, and cel44 - Pr were synthesized and analyzed by the technique, the mximm error between the actual composition and the gamma spectral analysis 82