where
oO
vs
.
sy = the activity per unit volume at the surface
s
:
Eatans ,
cm
and
sec
a = the reciprocal of the relaxation length (cm7!).
The detector response to a given flux of gamma rays of energy E,
incident at an angle
, can be given in terms of an effective detector
area, A, defined by
N
Aza.
The effective area,
(3)
in general, varics as a function of the gamma
ray angle of incidence and is normally written as
A= AR(E),
(4)
, where
Ay = the detector photopeak-count-rate for a unit
perpendicular to the detector face
flux incident
aan
y /cm”
- sec
R(@) = the ratio of tne detector response at an angle
»
and
to that
at © = 0°,
Both A, and R(:) are determined experimentally as a function of
energy;
calibrated reference sources are used with the detector mountce
in its standard field configuration.
Wa soiiiss