EXPERIMENT 9—3
Ï
219
which covers the front end contains a slot 0.2 centimeter wide
and 2 centimeters long over which a thin aluminum window about
0.025 centimeter thick or a cellophane window 0.008 Centimeter
thick is sealed with Duco cement or held rmly by a compressed
rubber gasket. The collecting rod is supported by means of an
amber plug as indicated about 0.5 centimeter from the inner wall;
its lead may come out the side or the end.
The chamber is lled
with argon at a pressure of 2 to 3 atmosphères.
‘
The electrometer should have a sensitivity of 10 millimeters
per volt or better.
entire electrometer circuit should be
carefully shielded in a grounded metal case. The voltage on the
.
ionization chamber may be 50 to 200 volts.
Ï
the crystal and chamber as shown in
gure 9—10 and start the tube. ' With the chamber xed in posi—
_
tion, slowly rotate the crystal until
maximum rate of deection
-
of the electrometer is observed. ‘ NOW rotate the crystal in steps ,
'
of 15 minutes, simultàneously moving the chamber by twice this
value.
Great care must be taken that the chamber movement is
just twice the crystal movement. Observe the rate of deection
of the electrometer, which is proporti0nal to the intensity of the'
.
X—rays, at each position of the crystal. As a characteristic X—ray
line is approached, the intensity Will increase
per-‘
haps to such a value as to make accurate readings of the electrometer difcult.
Then, a sheet of aluminumis placed across the
beam near D;
onc-half millimeter of : aluminum Will: reduce
-
molybdenum radiation to about
its unscreened value.
The ratio of
With—sand
screen ls
'
_
determined in the lower regionsof line and used to
values
_
at the higher points
unscreened
Near
the lines, the
_
steps should be taken verymuchdôser together
After
…
y11f sa 15?>:fr°m th.
…
Sidë 'ôffthed1rectbeamandanaccuraœsewng
i of:-at least0neofthelmesnehalf0fthe
’
,
anglemtheBraggequatwn(9—8)
Qi
.Ï
'
Ï
219
which covers the front end contains a slot 0.2 centimeter wide
and 2 centimeters long over which a thin aluminum window about
0.025 centimeter thick or a cellophane window 0.008 Centimeter
thick is sealed with Duco cement or held rmly by a compressed
rubber gasket. The collecting rod is supported by means of an
amber plug as indicated about 0.5 centimeter from the inner wall;
its lead may come out the side or the end.
The chamber is lled
with argon at a pressure of 2 to 3 atmosphères.
‘
The electrometer should have a sensitivity of 10 millimeters
per volt or better.
entire electrometer circuit should be
carefully shielded in a grounded metal case. The voltage on the
.
ionization chamber may be 50 to 200 volts.
Ï
the crystal and chamber as shown in
gure 9—10 and start the tube. ' With the chamber xed in posi—
_
tion, slowly rotate the crystal until
maximum rate of deection
-
of the electrometer is observed. ‘ NOW rotate the crystal in steps ,
'
of 15 minutes, simultàneously moving the chamber by twice this
value.
Great care must be taken that the chamber movement is
just twice the crystal movement. Observe the rate of deection
of the electrometer, which is proporti0nal to the intensity of the'
.
X—rays, at each position of the crystal. As a characteristic X—ray
line is approached, the intensity Will increase
per-‘
haps to such a value as to make accurate readings of the electrometer difcult.
Then, a sheet of aluminumis placed across the
beam near D;
onc-half millimeter of : aluminum Will: reduce
-
molybdenum radiation to about
its unscreened value.
The ratio of
With—sand
screen ls
'
_
determined in the lower regionsof line and used to
values
_
at the higher points
unscreened
Near
the lines, the
_
steps should be taken verymuchdôser together
After
…
y11f sa 15?>:fr°m th.
…
Sidë 'ôffthed1rectbeamandanaccuraœsewng
i of:-at least0neofthelmesnehalf0fthe
’
,
anglemtheBraggequatwn(9—8)
Qi
.Ï
'