THESE NOMOGRAMS give attenuation 
factors for lead and iron shielding slabs 
used with point sources of gamma radi- 
ation. 
The nomograms include the effect of 
buildup—the scattering of degraded 
* Miscellaneous data for shielding calcu- 
lations. Compiled by John Moteff. 
APEX 176 (1954). 
x 
7 16 
15 
6 
14 
5 
13 
= 
2 4 
= 
” 
uo” 
a 
c 
= 
oO 
oc 
- 
2a 
i=) 
wy 
i 
vD a 
°o 
ov 
a 
2 
radiation into the beam from all points 
of the absorber. Absorption coeffi- 
cients and buildup factors are from 
APEX 1765" 
Over most of the range, accuracy is 
10% or better. At extreme positions 
accuracy is better than 25%. 
Example. How thick must a lead 
shield be to reduce the dose from a 
LEAD 
3) 
(11.4 gm/cm 
Gamma Energy (Mev) 
point source of 1.0-Mev gammas by a 
factor of 2 X 10-8? We draw a line 
from the number 2 X 10-8 at the right 
through 1.0-Mev on the proper gamma- 
energy scale. Reading on the appro- 
priate side of the slab-thickness scale 
we find the answer: 9.67 in. 
x Ok O* 
I wish to acknowledge the assistance of Miss 
Joyce Berger, who drew the nomograms. 
10° 10° 
104 
4079 
107 
my 
a 
-_ Cc 
vo °o 
fe c 
° x 
c ' 
7 4076 fe 
= ° 
~ 
. 
nae °o 
‘= >- 
: E 
o 
hed ce 
c °o 
2 = 
= ° 
o J] 
=} c 
S iS 
+ 1077 = 
q 4072 
10-8 
4079 1073 
225 
