\
CONTENTS
vii
CHAPTER
PAGE
12. ALPHA, BETA AND GAMMA RAYS 260
The nature of alpha particles. Alpha ray spectra,—nuclear levels.
The range
of alpha particles. Range-velocity-energy—life relations.
A1r equivalent and stopping power. Ionization by alpha particles.
Primary beta ray spectra.
Gamma ray wave-lengths. Secondary
radiations.
The absorption of beta and gamma rays. Interaction
of beta and gamma rays With matter.
Experiments.
13. THE ACCELERATION or IONS 292
The multiple acceleration of ions,—Linear multiple acceleration. The
cyclotron. _T/ze production of high voltages,—D.C. types,—rectiers,
belt generators.
Impulse type. A.C. type. High-frequency type.
.
The accelerator tube.
Ion guns. -
1_4. ARTIFICIAL TRANSMUTATION.
.
.
307
-
The rst articial transmutatio.
Early alpha—proton _transmuta—
tions. The alpha particle is captured by the nucleus. Conservation of
momentum.
The reaction scheme. .The number and energy of the
ejected protons.
Resonance penetration. Excited states. The con.
servation of energy.
Calculation of nuclear masses.
Discovery of
‘
neutrons.
Scattering of fast neutrons. Discovery of positrons. The
—
discovery of articial radioactivity. The
of lithium
by protons. E'ective-cross—section.
Simple _captiire of protons.
—
Multiple reactions. Transmutations produced by deuterons. Photo—
_
disintegration. Pair production and annihilation. Transmutations by
.
fast neutrons. Slow neutrons. Uranium‘ and thorium bombarded by
'
neutrons. Theories of the nucleus. Experiment.
=
_
“
_
15. COSMIC RAY3342Introduction.
The great penetrating power of cosmic rays. Thé
'
,
__
ionization of gases by cosmic rays. The constancy of '
the average
intensity of cesmic rays. Short—time uctuations in intensity.
,
,.
‘
_.
cidence counters. The earth as. a magnetic spectrograph. Showere.
_
_
_
.
‘
_Experiment.
'
‘
-
.
j î:;i r
…
,LABORATORY TECHNIQUES -,
'
_
,
16VACUUMTECHNI QUE .
.
.‘
.
.
. ,x. j.
.'
., :_ .; ...
‘
,_
354
Theodumon Of vam—Introductlon Pumps W°rkmgfromatmos
umtsTheMcLeodgaugeTheeramgaugeMoleculargaages
=
:
CONTENTS
vii
CHAPTER
PAGE
12. ALPHA, BETA AND GAMMA RAYS 260
The nature of alpha particles. Alpha ray spectra,—nuclear levels.
The range
of alpha particles. Range-velocity-energy—life relations.
A1r equivalent and stopping power. Ionization by alpha particles.
Primary beta ray spectra.
Gamma ray wave-lengths. Secondary
radiations.
The absorption of beta and gamma rays. Interaction
of beta and gamma rays With matter.
Experiments.
13. THE ACCELERATION or IONS 292
The multiple acceleration of ions,—Linear multiple acceleration. The
cyclotron. _T/ze production of high voltages,—D.C. types,—rectiers,
belt generators.
Impulse type. A.C. type. High-frequency type.
.
The accelerator tube.
Ion guns. -
1_4. ARTIFICIAL TRANSMUTATION.
.
.
307
-
The rst articial transmutatio.
Early alpha—proton _transmuta—
tions. The alpha particle is captured by the nucleus. Conservation of
momentum.
The reaction scheme. .The number and energy of the
ejected protons.
Resonance penetration. Excited states. The con.
servation of energy.
Calculation of nuclear masses.
Discovery of
‘
neutrons.
Scattering of fast neutrons. Discovery of positrons. The
—
discovery of articial radioactivity. The
of lithium
by protons. E'ective-cross—section.
Simple _captiire of protons.
—
Multiple reactions. Transmutations produced by deuterons. Photo—
_
disintegration. Pair production and annihilation. Transmutations by
.
fast neutrons. Slow neutrons. Uranium‘ and thorium bombarded by
'
neutrons. Theories of the nucleus. Experiment.
=
_
“
_
15. COSMIC RAY3342Introduction.
The great penetrating power of cosmic rays. Thé
'
,
__
ionization of gases by cosmic rays. The constancy of '
the average
intensity of cesmic rays. Short—time uctuations in intensity.
,
,.
‘
_.
cidence counters. The earth as. a magnetic spectrograph. Showere.
_
_
_
.
‘
_Experiment.
'
‘
-
.
j î:;i r
…
,LABORATORY TECHNIQUES -,
'
_
,
16VACUUMTECHNI QUE .
.
.‘
.
.
. ,x. j.
.'
., :_ .; ...
‘
,_
354
Theodumon Of vam—Introductlon Pumps W°rkmgfromatmos
umtsTheMcLeodgaugeTheeramgaugeMoleculargaages
=
: