Rules Of Thumb For Gamma Radiation - Panasonic PT-DZ12000U Operating Instructions Manual

RULES OF THUMB FOR GAMMA RADIATION

1. The range of gamma rays (any photon) for energies from eV
to 10 MeV in air is from a few mm to 100 meters. The range
of those photons in water is from a few mm to several cm.
2. The dose rate 1 m above a flat, infinite plane contaminated
with a thin layer (1 Ci / m ) of gamma emitters is:
Energy (MeV)
0.4
0.6
0.8
1.0
1.2
3. The dose rate in rem/h per hour in an infinite medium
uniformly contaminated by a gamma emitter is 2.12 EC / ,
where C is the number of microcuries per cubic centimeter,
E is the average gamma energy per disintegration in MeV,
and is the density of the medium. At the surface of a large
body, the dose rate is about half of this. At ground level
(one-half of an infinite cloud), the dose rate from a uniformly
contaminated atmosphere is 1,600 EC rem/h per Ci / cm .
4. The radiation scattered from the air (skyshine) from a 100 Ci
60
Co source 30 cm behind a 1 m high shield is ~ 100 mR/h
(1 mSv/h) at 15 cm from the outside of the shield.
2
Dose Rate
rem/h
7.2
10
13
16
19
164
mSv/h
72
100
130
160
190
3