
65Physical Basis of Nuclear Forensic Science
which is specied as the “touching radius.” As mentioned earlier, the nuclear force
i
s
s
hort-ranged
a
nd
s
aturated.
T
herefore,
t
he
n
umber
o
f
n
ucleons
i
n
a
g
iven
v
olume
o
f
n
uclear
m
atter
i
s
r
easonably
c
onstant.
T
reating
n
uclei
a
s
r
oughly
s
pherical,
t
he
r
esult
i
s
t
hat
t
he
n
uclear
r
adius
i
s
p
roportional
t
o
t
he
c
ube
r
oot
o
f
t
he
at
omic
m
ass
A
:
r
=r
0
A
1/3
. Experimentally, for reactions with light ions, the proportionality constant
r
0
has been determined to be ~1.4 × 10
−13
cm. The Coulomb barrier is equal to E
C
e
valuated at the touching radius. Substituting into the preceding equation,
B Z
C T P T
1/3
P
1/3
in ...