' SOLON
ENERGY ABSORPTION BUILDUP FUNCTION
‘quals the rate of @ nergy
By produce
therefore
+
l,
1 ‘a)}
=
10
gt—
.
g—
7
2 Mev
a
—_
1
oO
6
u
mev
4
qd. (4) it is difficult
to perform
we we have made
use of two
GOLDSTEIN AND WILKINS (REF 4)
APPROXIMATE
CALCULATIONS
34
1
i mev
2
=
<
2 mev
b
1-—
sr
6b-—
&
s_
y < 28
a
4+-—
y>28
3
&
2-_/*®
t- MEAN- FREE PATHS
¥< 28
itt
2
4
|
€ calculations of
Goldstein
W-energy photons
on iron
tions become im
portant
Photoelectric regi
on, and
lev. Equation (8)
agrees
kins for 0.255 Me
y and
furnishes
|
6
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7, 54 (1952)
(A)
.
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id that a~ 1/y.’
Substitut-
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4
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idix.
+ ow)
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22
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26
Fre. 3. Buildup factors for Pb,
water. However, experimental values for the buildup function, normalized to
four mean free paths, are given for gammas from Hg” (0.28 Mev) (8) and are
in reasonable agreement with dq. (8). These buildup factors are exhibited with
those of Goldstein and Wilkins for comparison in Fig. 4.
It is possible to modify Eq. (1) to include the dose rate at a distanee from a
medium with a spherical boundary.
(9)
= eae|
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