42
Ol
21-year half-life as shown in the lower curves of Figures 36 and 37.
o
4 CENTER
1
oO
Oo
O
Oo
4
0.10
NA
Q SOUTH
©
Q WEST
& NORTH
-
KGD= 0.000
0.01
dot
ec
a
E
<
w
oO
&
2
CENTER
E
=
SOUTH
D WEST
A NORTH
Preliminary measurements of *°*Ra concentration in
a few samples from each of the trees as given in Tables
a
a
°
oO
oO
=
oO
O00!
20.01 -
o
O
40.¢
°
Ol
SCALE
BKGD= 0.015
re
+—T,= 21.4 yrs
0.002
0
i
|
20
l
40
!
60
i
80
9.0001 5
i
AGE (YRS)
Fic. 35—Variation of *°Pb specific activity with age of wood
in black oak.
20.40
BO
AGE
BO
Teo
(yrs)
120
0.07
Fic, 37—-The upper curve shows variation of ™°Pb 5
activity with age of wood in White Oak II. The lower
is the same with a constant background of 0.015 pCi *
subtracted (see text).
0.2
STABLE Pb VS AGE
4.0
ORS
o
O SOUTH
D WEST
& NORTH
&
nN
Y
a
o
oe
=
So
2
1 214 yrs
2
a
o
f
o
NL
—
oo
& ook
Q
1
3
oO
BKGD= 0.00
vA
a
<
~~
oO
Oo
0 OOlF
7.0!
Pb (.gm Pb/gm DRY)
=or
2.8
0.70F
WHITE OAK I
0.60
WHITE OAK IL
O50
SCALE
_>
BKGD = 0.01 O04, oge
0.000!
}
20
}
40
1
60
1
80
:
loo
1
120
AGE (yrs)
Fig. 36—The upper curve shows variation of ™°Pb specific
activity with age of wood in White Oak I; the lower one is
these data with a constant background of 0.010 pCi *°Pb/g sub-
tracted (see text).
0.40
0.30
0.20
i
|
20
40
l
60
!
80
l
i0O)—
120
TIME (YEARS)
Fic. 38—The variations in concentrations of stable le:
the various trees with age,
Pay
Vi