280
12.
ALPHA, BETA AND GAMMA RAYS
'
'
loge ]
,
the abscissae are values of d, log& [0 is the intercept on the
ordinate and # is the siope of the line, the negative sign indicating
Loggl0
-<——-— Slope =
Log€=l
.
,
.
d
.
FIG.
To determine
the absorption coefcient (,u).
that the slope is downwards from left to right. From the last
equation,
,
logelo—log.l
loge(Io/Î)
-
=
——°—
=
——
12—18
u
d
d
(
)
so
that this constant is dened as the logarithmic ratio of the
intensities at two points distant one centimeter in the absorbing
medium.
_
In the case of successive additions of layers of absorbing
.
'
terial, one takes
_
11 = Joe—”1.
12 = Joe—“dz,
from which
=
———1
<—)
12—20
,
.
d2-d10g ]2’
(
)-_
2.303
’Il)
.
*’
'
=
-—1
12—21
-
_
-
#
d
Og10
12
’
(
).
where Il is the intensity
of the rays after passing through d1 cm.—
of absorber, 12 is the intensity after passing through dz cm., and
2.303 is used to change from the Naperian to the common system
of
Thus, the intensity is measured bef0re (11) and afteif
12.
ALPHA, BETA AND GAMMA RAYS
'
'
loge ]
,
the abscissae are values of d, log& [0 is the intercept on the
ordinate and # is the siope of the line, the negative sign indicating
Loggl0
-<——-— Slope =
Log€=l
.
,
.
d
.
FIG.
To determine
the absorption coefcient (,u).
that the slope is downwards from left to right. From the last
equation,
,
logelo—log.l
loge(Io/Î)
-
=
——°—
=
——
12—18
u
d
d
(
)
so
that this constant is dened as the logarithmic ratio of the
intensities at two points distant one centimeter in the absorbing
medium.
_
In the case of successive additions of layers of absorbing
.
'
terial, one takes
_
11 = Joe—”1.
12 = Joe—“dz,
from which
=
———1
<—)
12—20
,
.
d2-d10g ]2’
(
)-_
2.303
’Il)
.
*’
'
=
-—1
12—21
-
_
-
#
d
Og10
12
’
(
).
where Il is the intensity
of the rays after passing through d1 cm.—
of absorber, 12 is the intensity after passing through dz cm., and
2.303 is used to change from the Naperian to the common system
of
Thus, the intensity is measured bef0re (11) and afteif