properties of eilipecids of revolution. In Figure 1.1, the source’
anddetector lie at the
foot of a family of such ellipsoids such that
y+ Ps =svt'
oa
Where: ¥ “4 z = neutron velocity
<[~
In Formula 3 and the subsequent definitions the time of arrival, ¢’, is measured in units
ta
for convenience.
a
1
g(cos 6) n(Z) Ag (%) Ap (*)
K(Z, ¢') =— f dx
I
Where:
-_
ce’? - x?)
b=1 or 228
zt!
x =a variable of integration
a@ =detector area
cos 6 =
2-H x?
pe x2
Li's
Z=Zp_ a+ mm
2
n(Z) = density of scatterers (oxygen and nitrogen nuclei) at altitude Z
Z =H+s ¢’x-1)= Zy + EX
H = shot altitude, 2 =H +
g (cos 4) = differential scattering cross-section for neutrons.
Ag (x) = exp [ - f
Q
rm
tT
Ap (¥) = exp | 0
dr,
|, (attenuation factor)
dry
YZ)
; (attenuation factor)
12
(3)