CERN Program Library Long Writeup W5013 - CERNLIB ...

α
r
N Av
A
Z
F c (Z)
fine structure constant;
classical electron radius (in cm);
Avogadro’s number;
atomic weight;
atomic number;
Coulomb correction function.
[
]
F c (Z) =(αZ) 2 1
1+(αZ) 2 +0.20206 − 0.0369(αZ)2 +0.0083(αZ) 4 − 0.0020(αZ) 6
ξ(Z) =
ln 1440
Z 2/3
ln 183
Z 1/3 − F c (Z)
for a compound or mixture:
1
= ∑ ρX 0 i
p i
ρ i X 0i
where p i is the proportion by weight of the i th element. For more information on the organisation of the
data in memory see [CONS199].
The effective absorption length λ is defined as the interaction length of a 5GeV pion in the material:
1
λ = ∑ i
p i
1
= σπ i (5GeV )N Av
g −1 cm 2
λ i λ i A i
Once this value has been determined, an effective hadronic atomic weight (A h−eff ) is calculated by the
routine GHMIX [3] and stored in the data structure.
CONS110 – 2 52