TOTAL-ABSORPTION GAMMA-RAY SPECTROSCOPY dt TIT = a TOF _ < = _ r= 0.5107 MEV 7 3 4 = 8 oO IE — _ = oO 4d — > o L- < UU 7 -- —_ 2 = - oo o 2 ) & = 193 8 of £ - IE 2 w — S . o 3 2 g~ oF aa = e o . > 4 ae 383 7. = FO s PC = sO = N > £3 8: 5 | Fa — | | J — 7 — Qa 8 > 4 = — La 1 i | -— a 3 a _ : 0 10 tion . . Fig. 14——Field ganiuna-ray spec tra for annihilation radiation, 103R 4, and ®RhK. i 20 | jd Ld 30 40 50 60 70 CHANNEL NUMBER ] 80 | 90 100 1 The single spectrum per day results for each major fallout radia- contributor are shown in Figs. 15 to 19. Figure 15 shows the amounts of '44Pr from December 1962 to July 1964. The decrease from decay and the increase from fallout are Seen, Similarly, Fig. 16 shows 4407 a and the capability of the method to resolve zero amounts, Figure 17 shows the “Mn amountsthat built up to a maximum in March 1964. Figure 18 represents theZr—*°Nb amounts, and Fig. 19 represents the ‘1Cs amounts. The gamma-ray energy at 0.662 Mevis sufficiently low that many factors cause the amounts measured to vary. Soil moisture is a large factor. The long half-life of 1°’Cs allows time for the radio- nuclides to penetrate more deeply into the soils, and the effective source is one similar to ‘°K, one of an infinite slab. Also, errors both in energy calibration for each spectrum and in the individual source calibrations can create errors, especially when there are very large amounts of the adjacent overlapping data from decay of *Zr—**Nb. The