15—8.
SHOWERS
'
351
'
cosmic rays consist of charged particles. Further, if the-observed '
rays had been secondary charged particles produced in theatmos—.
phere, say by photons, the earth’s eld could not have curved them
suiciently before they reached the_observer to account for the
various phenomena. _Îust which charged particles are involved is
not yet certain but there is some tentative.evidenCe that protons .
and positive and negative electrons
.
15—8.
Showers.——It has been pointed out in theprecedi‘ng
chapter, in connection with the discovery of the positron, that
large” numbers of ionizing particles are occasionally observed in an
expansion chamber. With a magnetic eld, the tracks are curved,
some to the right, some to the left, and in approximately equal
numbers.
As many as one hundred tracks have been observed in
one of these “ showers,” diverging in a narrow angle fr0m a small
area.
From the number and 1 length Of the
'
_
,
«
tracks, the number of droplets on each, the cur—_
vature in a magnetic __eld and their,absorption
ÿ
_
-
'
in various substances, it is possible to estimate
‘
W _. .
_
the total energy in the shower.
This isof the
®
'
order of 108 to 1010 electron volts, thésame as
:”
.
_
that deduced for the energy of cosmic rays._
Showers may also be
studied"with counter F1é.
s:udy
‘
tubes, as in gure 15—10.
_
Three tubes
15
are the _ production ‘of
placed as shown and
*
_
showers. f
.
_
circuit so thationization muSt,take place
in
?
_
of them at practically
to
a
ROSSI
'
found that, when
P1êœd'ab0V‘3
the. ”tubes, the: number
increased until—
W 38 about
crie centimètèr»of.lead,
,.
_
‘
A.
and
it is
-
.kn0wn that they1nçreaseWl‘Chalt1tude
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=
.
_
Theburstsol:»s<—:rvedm10f112at10nCha—mbêfsC°nSlsmfùOnÇ
°r‘
When
.“
chamberthenumberofburstsobservedmumtt1melncœasesat* @
 rst
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'
…
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—