ami
ta 6
ave
Reference 14.
as follows.
Degradation of these six spectra by penetration of about 1 ainch of steel was als. estitiat
An unattenuated gamma-energ, spectrum (broken into n energy, intervals) has an average cne:.
{..
of U, Mev,em™=see for the jth energy interval D) Mev wide. After attenuation by x-cn. vt steel the ener.
flux from the jth energy interval has been reduced to U|B, ext (—ux). assuming plane monodireet. nil
1-
é
j
§
diation for simplicity, where B, 1s an energs ~buildup tactor Gc termined by cross-interpo.ation in Re tere
11. and uw is the total absorption coefficient per centimeter of steel (at the energy representative cf the ot
interval) determined from Reference 15. To reduce tne computational complexity. it Was assume. that
(for energy originating in the jth energy interval the attenuated energy flux per unit energy interval m1
came umformly distributed over the interval
emphasizing the low energies (Figure B.10).
D,.
This assumption biases the results sonuwhat bo oar -
The energs flux for the pth intervals (p=)
originatins fr_>
the jth interval. is representea by
,
(0, Dj) U|B, exp (-un
(Bt
Summing all of the attenuated and degraded energ. flux (Ap) for the pth energy interval. originating mu:
all intervals that can contribute to it. results in
JEP
t
(B.2
An cNamplh of the eficct of this assumed degradation on one of the assumed gamma-energy spectra 1s presented in Figure E.11.
The energy flux for each of the energy intervals of the twelve energy spectra (six original and six de-
graded) was converted to an equivalent dose rate by using conversion factors determined from Reference
15. These dosc rates were used to calculate percent dose-rate contributions from energyintervals representative of the energies at which the integrated detector responses had been calculated (Tables B.7 and
B.S). These percentages were used as weighting factors applied to the data of Figures B.6 through B.9.
thereby obtaining the overall responses to the assumed spectra in relationship to the biased-fieldcalibration.
GITR bias-correction factors were obtained by averaging the reciprocals of the weighted
integrated responses to the assumed energy spectra for the various idealized radiation-source geometries
(Table B.Y).
i
x