CHAPILE 4
GARKIMA ENERGY-DOSE SPECTRUM
kolo
PEOTON FLUX SPECTREM
The fallont material eccpoaited on the iruund precuced a large area
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oer.
plane cource ot radiation, Re Pore a total gerra dose could be calcu.
lated, it was ‘ne caer ary Ly correct the dos: rate readings in air taken
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re
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5
oo
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ts
Sail
ae
with the survey
the meter resperse factora found to te
necessary for cif Ceieab ancrey re,ues,
further ; to cattnate the cise .
tribution of doce with depth in tissue required a knowledco of cnerpy
distribution of the incarine flux in a eiven exposure ceometry,
For a source ag large as these fallout fieles, this ener,y distri+
tution will te a funeticn toth of the oripinal source ener. and the
enerry deprzdation effect of passage through intervening air, A mathod
of evaluating the later, which was due mainly to Compton scattering in
air for the fission ;rocuct cneryy recien, has been presented in
Reference 7, This technique was emplcyed here, Enerry spectra of the
CASTIL fallout itself his been measured with a scintillation spectrometer on a series of cluud samples as early as H+ h days, The data have
been published in Refem-nce 8, The preliminary data on the earliest of
these, a 9h-hourecld cloud sample, were used in tim calculations sn~
mariz ed in Reference 16,
These are given in Table ).1 (tan forenee 9).
This 9h-hour sanple froma Shot 1 reprerscnts the closest apprcach to the
actwal tine during which the exposures occurred,
After the conclusion of the test series, analysis of early data
from other shots contimed and later spectra for all shots were analyzed, None of the other spectra are for times as early as H + 94 hours,
For the later detonations the proportion of tipe3? (average parma -ener-
gies By = 243 kev, WO percent; E2 = lud kev, Lt percent; £3 = 9 kev,
9 percent) in the fallcut samples was foun“2 to be much hisher than
that viven in Table k.1, An extreme care, for exarple, is the dataa for
Shot 4 on 26 April at H+ 5.3 days which is given in Tatle 4,2,
Here
the low eneryy portion of less than 100 kev was measured as £0 jercent
of the total photon flux, Two later determinations on ancther Shot 1
sarple (1-L, Tatle 3 of Heference 3) show these low energy proportions
as 55 percent at H+ 4.1 days and Sh percent at H + 5,2 days a3 well
(Tatles h,3 and k,l),
Later data tus tended to show that the initial
estinate of low ener,;y redidtion was low,
Hence, revised estirates of
the total doses will te presented here cn the basis of the additional
data for which the counting statistics were tetter than on the Shot 1,
H+ 9h hour sarple, These spectra, it must be emphasized, are for
17
.