218
9.
X-RAYS
,
'
EXPERIMENT 9—3
«
..
STUDIES WITH A BRAGG SPECTROMETER*
'
—
(Read section 9—-5, about
“
Protection from X—rays ”)
»
1. An X—ray spectrum and the wave—lengths of the character—,
istic lines of a given target material may be measured by means of
ï
the apparatus shown in gure 9—10.
'
-
Æppamtus.—The X—ray tube should preferably be of the hot— -
cathode type.
If the target is made of molybdenum, the voltage
applied to the tube should exceed 30 kilovolts, a value of 50 to
‘
'
60
kilovolts proving satisfactory. In any case, the voltage
should be well above the value needed to excite the characteristic
,
lines to
as calculated from the relation V6 : 1111.
A
-
typical voltage supply is shown in gure 9—3 While other Circuits ;]
'
are given inchapter 13 and a lament transformer is described in
chapter 19.
In gure 9—10, the anticathode of the x—ray tube should be as
Close to the slit  as the electrical insulation will permit.
and B should be about 0.3 to 0.4 millimeter wide and 1.5 centiè
.
meters long in lead sheets 3 to 4 millimeters thick, with the longer
_
dimension parallel to the crystal face Çperpendicular to the
They should be about 20 cehtimeters apart. Slit D, likewise par—
'
allel to the crystal face, should be about 0.3 centimeter wide and
'
1.5 centimeters long in a similar lead sheet.
‘
The spectrometer table, upon. which the crystal € is
_
should be capable of giving angles to at least 2 minutes of arc
,
The crystal C may be calcite. The alignment of the slits
.
_'
is made With the aid of a uorescent screen.
'
_
The ionizati0rî chamber ]
,.
Which is mounted on an extenswn
.
arm
the Center of the table, is surroundeüî
_
w1tha leadsheath
thick and is locatedas
“
just outside- the circle; The
X—raybeammust not strike the
rod“ or the walls,only
.
.
theends ,—Ï9f1l The lc—Hamber
& bràssfÿ11beîabout2@
' _ *Theauthor15 1ndebtedtoDrE
these experiments
9.
X-RAYS
,
'
EXPERIMENT 9—3
«
..
STUDIES WITH A BRAGG SPECTROMETER*
'
—
(Read section 9—-5, about
“
Protection from X—rays ”)
»
1. An X—ray spectrum and the wave—lengths of the character—,
istic lines of a given target material may be measured by means of
ï
the apparatus shown in gure 9—10.
'
-
Æppamtus.—The X—ray tube should preferably be of the hot— -
cathode type.
If the target is made of molybdenum, the voltage
applied to the tube should exceed 30 kilovolts, a value of 50 to
‘
'
60
kilovolts proving satisfactory. In any case, the voltage
should be well above the value needed to excite the characteristic
,
lines to
as calculated from the relation V6 : 1111.
A
-
typical voltage supply is shown in gure 9—3 While other Circuits ;]
'
are given inchapter 13 and a lament transformer is described in
chapter 19.
In gure 9—10, the anticathode of the x—ray tube should be as
Close to the slit  as the electrical insulation will permit.
and B should be about 0.3 to 0.4 millimeter wide and 1.5 centiè
.
meters long in lead sheets 3 to 4 millimeters thick, with the longer
_
dimension parallel to the crystal face Çperpendicular to the
They should be about 20 cehtimeters apart. Slit D, likewise par—
'
allel to the crystal face, should be about 0.3 centimeter wide and
'
1.5 centimeters long in a similar lead sheet.
‘
The spectrometer table, upon. which the crystal € is
_
should be capable of giving angles to at least 2 minutes of arc
,
The crystal C may be calcite. The alignment of the slits
.
_'
is made With the aid of a uorescent screen.
'
_
The ionizati0rî chamber ]
,.
Which is mounted on an extenswn
.
arm
the Center of the table, is surroundeüî
_
w1tha leadsheath
thick and is locatedas
“
just outside- the circle; The
X—raybeammust not strike the
rod“ or the walls,only
.
.
theends ,—Ï9f1l The lc—Hamber
& bràssfÿ11beîabout2@
' _ *Theauthor15 1ndebtedtoDrE
these experiments