JACOBI AND ANDRE
3808
TABLE 1.
active equilibrium
near ground level
heights (see Table
An experimental
Calculated Deviation of Radioactive
Equilibrium between Rn”? and Its Short-Lived
Decay Products
Activity Ratio
the boundary layer of the radioactive equil
1.00
rium between Rn™ and Pb™ or Bi™ is possi
by simultaneous measurements of Rn™with
ion chamberorthe scintillation chamber met!
and of Pb™ and Bi™ by the filter method.
low turbulence (cases IWN and WNN) the deficiency is rather large near ground level b ut
though in a rather undefined terrain, were m:
by Jacobi et al. [1959]. The average Bi™/R
ratio for 35 measurements at a height of 1 to
meters—most of them during daytime—was
to 0.5; radioactive equilibrium was found c
during rather strong inversions at night anc
the morming. Minimum values of about 0.2
0.3 were observed in the noon and afternoo:
An exact proof of the theoretical results
quires measurements of the Rn™ and fT
(Bi™) profiles in the boundary layer during
riods of rather constant atmospheric stabil
Nuclide
Ratio
Pot4/Rn®
Pb**/Rn2
+
ms
Bi?4 /Rn*
0.1
IWN 0.66
WNN 0.56
NNN 0.77
SSN
0.90
IWN 0.31
WNN 0.31
NNN 0.66
SSN
0.83
IWN 0.23
WNN 0.25
NNN 0.63
SSN
0.80
Height, m
1
10
0.98
0.85
0.88
0.938
0.73
0.54
0.76
0.85
0.62
0.45
0.7
0.82
1.00
0.99
0.95
0.96
0.99
0.82
0.84
0.88
0.97
0.73
0.80
0.84
100
few simultaneous measurements of this ki
1.00
1.00
0.98
1.00
0,99
0.94
Q.9L
1.00
0.88
0.90
0.88
decreases rapidly with increasing height. With
But the theoretical results demonstrate the
increasing turbulence the deviation from radio-
sibility of obtaiming valuable information on
10"
Specific activity (dps/cm’)
wo
Turbulence
Case
with Rn™ will be smal
but will extend to grea
1).
proof of the disturbance
—— eee
-_————
10
owe ee
wee ee
——— oo
16
1C
lem
10cm
Im
10m
com
1km
10km 30kr
Altitude
Fig. 7. Vertical profiles of Pb™° and Po”, calculated with Ero = 1 Rn atom/cm* see and with
the K profile NNN (parameter 7 = half-life of removal).