30 Nuclear Forensic Analysis
Thus, by 1905, the rst radiochemists had demonstrated that radioactive decay
i
nvolved
t
he
s
pontaneous
t
ransmutation
o
f
a
n
a
tom
o
f
o
ne
c
hemical
e
lement
i
nto
t
he
a
tom
o
f
a
nother,
a
ccompanied
b
y
t
he
o
bserved
r
adioactive
em
issions.
T
he
i
ntensity
o
f
t
he
r
adioactivity,
a
nd
t
herefore
t
he
r
ate
o
f
t
ransmutation,
w
as
k
nown
t
o
b
e
p
ro-
portional
t
o
t
he
n
umber
o
f
a
toms
i
n
a g
iven
c
hemical
p
reparation.
T
he
s
peed
w
ith
which the change took place was shown to be dependent on the identity of the radio-
active
s
pecies.
T
hese
o
bservations
g
ave
r
ise
t
o
t
he
s
tatistical
t
heory
o
f
r
adioactive
d
ecay,
w
hich
w
ill
b
e
d
iscussed
l
ater.
T
he
a
tom
w
as
n
o
l
onger
s
een
a
s
s
tructureless
a
nd
i
ndivisible.
The
d
ifferent
r
adioactive
d
ecay
m
odes
a
nd
d
ecay ...