Biomedical Engineering Reference
In-Depth Information
If the sample was originally pure
210
Pb, then how old is it
at time
t
= 0
?
(b)
What is the mean life of a
226
Ra atom?
18.
59
Fe has a half-life of 45.53 d.
(a)
19.
What is the mean life of a
59
Fe atom?
Calculate the specific activity of
59
Fe.
(b)
How many atoms are there in a 10-mCi source of
59
Fe?
(c)
0
a sample consists of 2 Ci of
90
Sr and 8 Ci of
90
Y.
20.
At time
t
=
What will the activity of
90
Y be in the sample after 100 h?
(a)
At what time will the
90
Y activity be equal to 3 Ci?
(b)
136
Cs (half-life
=
13.7 d) decays
(
-
)
into
136m
Ba
21.
β
)
into stable
136
Ba:
(half-life
=
0.4 s), which decays
(
γ
-
--------
β
γ
--------
136
Cs
136m
Ba
136
Ba.
→
13.7 d
→
0.4 s
(a)
Calculate the decay constant of
136
Cs.
(b)
Calculate the specific activity of
136
Cs.
Starting with a pure 10
10
-Bq sample of
136
Cs at time
t
(c)
=
0
,
how many atoms of
136m
Ba decay between time
t
1
=
13.7
d
(exactly) and time
t
2
=
13.7 d + 5 s
(exactly)?
22.
Show that Eq. (4.40) leads to secular equilibrium,
A
1
=
A
2
,
under the appropriate conditions.
23.
Show by direct substitution that the solution given by Eq. (4.40)
satisfies Eq. (4.39).
A 40-mg sample of pure
226
Ra is encapsulated.
(a)
24.
How long will it take for the activity of
222
Rn to build up to
10 mCi?
What will be the activity of
222
Rn after 2 years?
(b)
What will be the activity of
222
Rn after 1000 years?
(c)
What is the ratio of the specific activity of
222
Rn to that
of
226
Ra?
(d)
25.
Verify Eq. (4.43).
26. (a)
Verify Eq. (4.44).
(b)
Show that the time of maximum total activity occurs earlier
than the time of maximum daughter activity in Fig. 4.5.
(c)
Does Eq. (4.43) apply to
A
2
when there is no equilibrium
(Fig. 4.6)?
27.
To which of the natural series do the following heavy
radionuclides belong:
21
83
Bi,
21
84
Po,
230
90
Th,
23
92
U, and
22
88
Ra?
28.
The average mass of potassium in the human body is about
140 g. From the abundance and half-life given in Appendix D,
estimate the average activity of
40
Kinthebody.
29.
An atmosphere contains radon and its short-lived daughters in
secular equilibrium at a concentration of 52 Bqm
-3
.
