287Techniques forSmall Signatures
completely absorbed and will contribute to the intensity of the background contin-
uum
at
e
nergies
l
ower
t
han
t
he
p
hotopeak.
O
ne
c
omponent
o
f
t
his
c
ontinuum
i
s
ca
used
b
y
C
ompton
i
nteractions,
i
n
w
hich
a
p
hoton
i
s
s
cattered
o
ut
o
f
t
he
d
etector
c
rystal
i
n
t
he
d
irection
f
rom
w
hich
i
t
ca
me,
t
ransferring
a
q
uantity
o
f
e
nergy
t
o
t
he
C
ompton
e
lectron
(
which
i
s
a
bsorbed).
T
he
e
lectron
i
s
k
inematically
c
onstrained
to a maximum value that is less than that of the incident photon, and it gives rise to
a
s
udden
i
ncrease
i
n
t
he
i
ntensity
o
f
t
he
c
ontinuum
at
e
nergy
v
alues
l
ess
t
han
t
he
m
aximum
e
lectron
v
alue,
t
ermed
a
C
ompton
e
dge.
T
he
C
ompton
e
dge
a
ssociated
w
ith
t
he
1
408-keV
p
hotopeak
i
s
l
ocated
n
ear
c
hannel
2
400
a
nd ...