-
EXPERIMENT 12—1
7
283
is the typical ejection of photo-electrons as in the case of alpha
beta and low-frequency X—rays. For higher frequencies and the
ghter elements, the scattering of the gamma
from free
_
electrons (Compton effect) predominates. For exceedingly high
.
frequencies, positron-electron pairs are formed5 as discussed in
chapter 14.
-
—
'
_
TABLE 12—1.—SUMMARY OF RADIOACTIVE RADIATIONS
'
..
Rays
Alpha
Beta
Gamma
Nature
Helium
or
Electrons
Very short electro,He
,
_
magnet1crad1aüons
Charge
+ Ze
—e
None "
'
Charge/Mass
=
4823
€—
=
4M
gram
m
grain
—
1.42 >< 109 to
0.29: to 0.96; or
.
,
10
'
.
'
2.06 >< 109
0'87
X 10
t°
c = 3 >< 101°‘9Ë
—
Velomfy
sec.
>< 101021“;
'
sec.
.
about Îl_o that of beta
sec.
.
_
rays
'
_
I onization
Great; along straight, Moderate; curved tra— smàu; throughout
marrow beams
Jectones
the gas
R
2.37 to8.16 cm. in air'
Ç°
’
ange
(76, 0° C.)_ .
7—
“
_
-
; ÏgM9deratebä;i 3mm With, diî€ukY; 25
cmalu
to” _cm'. iron. ,; = 0.096
‘
_
_
_
-
1
,:,gl
55001na1ummum
-t02700in aluminum
_
,
Wave—length
_
0.0047 ang.
'
1
…Str°ms
.
.
5*
Theapparatüsf@rmeawmgtherangeofalphapartmles at
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nectedtothest0PcockPartlaÿeVacuatmgtheglasstube :B