282 Nuclear Forensic Analysis
be emitted, but if the dynode is fabricated from the proper materials, the multiplica-
tion
f
actor
ca
n
b
e
a
s
m
uch
a
s
5
–10.
T
o
a
chieve
e
lectron
g
ains
o
f
1
0
6
or more, all PM
t
ubes
e
mploy
m
ultiple
s
tages.
S
imilar
t
o
e
missions
f
rom
t
he
cat
hode,
s
econdary
e
lec-
trons
e
mitted
f
rom
t
he
s
urface
o
f
t
he
rst
d
ynode
h
ave
v
ery
l
ow
e
nergies
a
nd
m
ust
b
e
a
ccelerated
t
oward
a
s
econd
d
ynode
t
hat
i
s
b
iased
p
ositively
r
elative
t
o
t
he
rst
o
ne.
T
his
p
rocess
ca
n
b
e
r
epeated
a
s
m
any
t
imes
a
s
n
ecessary.
I
f
t
he
m
ultiplication
factor at each dynode is ve, then 10 stages will yield an overall tube gain of 5
10
, or
a
bout10
7
. The last dynode is actually the anode of the PM tube, and the current pulse
i
n the anode is amplied to give the tube ...