"
12—1.
THE NATURE OF ALPHA PARTICLES
261
tricity just does not take place.
alpha particle, in pass—
ing through the tube, is able to create sufcient ions to cause a ‘ _
_
discharge to occur. The potential across the tube then falls to
a few volts because of the ir drop in—the resistance 7 and the discharge ceases. The potential drop across r may be used to operate
«
a loud speaker or a mechanical counter.
(See chapter 18 for fur,
ther details.)
.
«
.
The average number of particles which enter the tube each
second is obtained.from' a long series of readings and multiplied
by the ratio of 47r to the solid angle 5 to obtain the total number
of particles which leave the source in all directions each second.
'
In this manner it has been found that one gram Îof radium, free
from its products, emits 3.71 x 1010 alpha particles each second.
Another method for directly counting the number of particles
_
to observe the scintillations which they produce on a piece of
diamond. ' At rst, it was not known whether every alpha particle
produced a scintillatioh, but comparison with the Geiger counter
has shown this to be true.
?
.
—
It has been found that a small percentàge, perhaps one-quarterof one per cent, of the alpha particles are neutralized
pass
through the apparatus of gure 12—1. After making this correc_
tion, it was found that a.total charge of32.9 e.s.u. was carried by
'
the 3.71 X 1010 alpha particles
by one gram of radium in
.
one second and that a total charge of 3.77*><
e.s.u. accom—
panied the
by;agiven sample of,radium F
second.
When ave‘ragéd With determinations made With
'
other sources, itwas shown
c/zc‘zrge (E.-,,) of the
alpha”.
an
Thus,
= +
X478 X10—1068u=956X10_10 e.s.u.
'
That the alpha,
of “ajhelium atom—; lesswtwo
.
electrons, 16,ofalzelzum ucleus, hasb eenver1e by the‘.gfoow_
‘
‘
mgexpenmentRad1umemanaü@nmcllectedif.s_is ambe 4»
,
gure12—2,Wh®seglasswausaœonly1mm1nth1ckness The — ‘
ÎwallsarethensuîClentlÿthlnS®thatïealPhaPafüdesfmïthe
emanatwnand1tsdecaypmuctscaescaPemtotheh1ng
.
12—1.
THE NATURE OF ALPHA PARTICLES
261
tricity just does not take place.
alpha particle, in pass—
ing through the tube, is able to create sufcient ions to cause a ‘ _
_
discharge to occur. The potential across the tube then falls to
a few volts because of the ir drop in—the resistance 7 and the discharge ceases. The potential drop across r may be used to operate
«
a loud speaker or a mechanical counter.
(See chapter 18 for fur,
ther details.)
.
«
.
The average number of particles which enter the tube each
second is obtained.from' a long series of readings and multiplied
by the ratio of 47r to the solid angle 5 to obtain the total number
of particles which leave the source in all directions each second.
'
In this manner it has been found that one gram Îof radium, free
from its products, emits 3.71 x 1010 alpha particles each second.
Another method for directly counting the number of particles
_
to observe the scintillations which they produce on a piece of
diamond. ' At rst, it was not known whether every alpha particle
produced a scintillatioh, but comparison with the Geiger counter
has shown this to be true.
?
.
—
It has been found that a small percentàge, perhaps one-quarterof one per cent, of the alpha particles are neutralized
pass
through the apparatus of gure 12—1. After making this correc_
tion, it was found that a.total charge of32.9 e.s.u. was carried by
'
the 3.71 X 1010 alpha particles
by one gram of radium in
.
one second and that a total charge of 3.77*><
e.s.u. accom—
panied the
by;agiven sample of,radium F
second.
When ave‘ragéd With determinations made With
'
other sources, itwas shown
c/zc‘zrge (E.-,,) of the
alpha”.
an
Thus,
= +
X478 X10—1068u=956X10_10 e.s.u.
'
That the alpha,
of “ajhelium atom—; lesswtwo
.
electrons, 16,ofalzelzum ucleus, hasb eenver1e by the‘.gfoow_
‘
‘
mgexpenmentRad1umemanaü@nmcllectedif.s_is ambe 4»
,
gure12—2,Wh®seglasswausaœonly1mm1nth1ckness The — ‘
ÎwallsarethensuîClentlÿthlnS®thatïealPhaPafüdesfmïthe
emanatwnand1tsdecaypmuctscaescaPemtotheh1ng
.