Air Kerma-rate constant Γ
δ
∑
⋅ ⋅
⋅
=
i
E,
tr
i
i
i
En
4
1
Γ
α
δ
ρ
μ
π
0.9
2.0
1.0
2.3
1.4
0.8
0.73
3.3
0.06
X.X average number of photons
emitted per decay with E > 10keV