PROBLEMS
457
_
11—12. The number of counts per minuté in a counter tube, as determ1ned by measurements made over a long period of time, is 480 when the
source
IS present and 60 when it is absent.
Compute the probable error
.
(1n percentage) when the observation time is ten minutes. What is the
relative sensitivity of the instrument?
_
12—1. A beta ray has an energy of 106 e.v.
What is the
=
ing value of Hr for this particle? Compare the relativistic and the non—
relativistic values.
(1368 &? (non) 1064)
12—2. The ranges of the alpha particles from radium A and radium
C’ are 4.69 cm. and 6.94 cm. respectively. If the velocity of those
from radium A is 1.699 >< 109 cm. per sec., what is the velocity of those
from radium C’?
,
_
12—3. The range of the alpha particles from radium A is 4.69 cm.
at
76 cm. mercury pressure and 15° C.
What will the range be at "74 cm.
and 22.7° C.?
12—4. The absorption coefcients of beta rays in_aluminum for ura"
_nium Xl and uranium X2 are 460 and 18,” respectively.
What thick—
messes of aluminum are necessary to reduce each to one one-hm‘1dredth of
the original intensity?
—
_‘
_
12—5. The coefcient of absorption of a gamma ray
is proportionalto
the density of the absorbing material. What thickness of cast 1ron_wl
reduce the intensity of a gamma ray by the same amount as one inch
oflead?
_
v
‘
_
_
__
12—6. The absorption coefcients of beta rays_in aluminum
for radium
C are 13 and 50.
What will be the reduction1n 1ntensrty of the
penetrating of these rays
when passed_thmugh @ sheet of aluminum
which reduces the less penetrating
to one one—hundred'Çh 0f_th.e
value?
_
_.
__
-
;"
.
_
12—7. What perœntage
of beta rays_
rays from radium C will penetrate
0212cn‘1. of alurmnumPWhO'SCa SOÏP“
.
tion coefcients for these rays arel8and014resp‘îCtlVelÿ
__
'
-
.
‘
‘
;
-
12—8. 47.97 cm. of aluminum
»
rium C” to one one-hundredthdf
lsthecoef—
*_ ‘
cient Of
'
"
13—1. Calcùlate the energy oftheemergentprotonslnaSmaHf°Yâ“îgä
whose eld strength is 5000 gausseSThemax1mumrîdlus
06
;
_
i
_14…—1—
A
beam0f°“em…Ëmperäî?oekliovoitsFromthe
_
‘—
VQltmeter across theaccelefatm8tuerealhartldesmaybeï‘î
_
‘
1
”
koW
_
457
_
11—12. The number of counts per minuté in a counter tube, as determ1ned by measurements made over a long period of time, is 480 when the
source
IS present and 60 when it is absent.
Compute the probable error
.
(1n percentage) when the observation time is ten minutes. What is the
relative sensitivity of the instrument?
_
12—1. A beta ray has an energy of 106 e.v.
What is the
=
ing value of Hr for this particle? Compare the relativistic and the non—
relativistic values.
(1368 &? (non) 1064)
12—2. The ranges of the alpha particles from radium A and radium
C’ are 4.69 cm. and 6.94 cm. respectively. If the velocity of those
from radium A is 1.699 >< 109 cm. per sec., what is the velocity of those
from radium C’?
,
_
12—3. The range of the alpha particles from radium A is 4.69 cm.
at
76 cm. mercury pressure and 15° C.
What will the range be at "74 cm.
and 22.7° C.?
12—4. The absorption coefcients of beta rays in_aluminum for ura"
_nium Xl and uranium X2 are 460 and 18,” respectively.
What thick—
messes of aluminum are necessary to reduce each to one one-hm‘1dredth of
the original intensity?
—
_‘
_
12—5. The coefcient of absorption of a gamma ray
is proportionalto
the density of the absorbing material. What thickness of cast 1ron_wl
reduce the intensity of a gamma ray by the same amount as one inch
oflead?
_
v
‘
_
_
__
12—6. The absorption coefcients of beta rays_in aluminum
for radium
C are 13 and 50.
What will be the reduction1n 1ntensrty of the
penetrating of these rays
when passed_thmugh @ sheet of aluminum
which reduces the less penetrating
to one one—hundred'Çh 0f_th.e
value?
_
_.
__
-
;"
.
_
12—7. What perœntage
of beta rays_
rays from radium C will penetrate
0212cn‘1. of alurmnumPWhO'SCa SOÏP“
.
tion coefcients for these rays arel8and014resp‘îCtlVelÿ
__
'
-
.
‘
‘
;
-
12—8. 47.97 cm. of aluminum
»
rium C” to one one-hundredthdf
lsthecoef—
*_ ‘
cient Of
'
"
13—1. Calcùlate the energy oftheemergentprotonslnaSmaHf°Yâ“îgä
whose eld strength is 5000 gausseSThemax1mumrîdlus
06
;
_
i
_14…—1—
A
beam0f°“em…Ëmperäî?oekliovoitsFromthe
_
‘—
VQltmeter across theaccelefatm8tuerealhartldesmaybeï‘î
_
‘
1
”
koW
_