Problem
229
68. Describe the recent developments in the detection and measurement of radiations. What is the smallest amount of
198 Au expressed in microcuries that you
can measure with ± 10% standard deviation? Assume that you are provided with
a well-type scintillation counter which gives an efficiency of 25.6%. Let each
counting be done for 10 minutes. The background count was 653 obtained in 10
min of counting.
69. Find out the decay scheme for
64 Cu:
The sample is present in a solid form. How will you prepare the source for
counting this isotope and which counter would you select for counting purposes?
Explain.
70. Find out the decay scheme of
90 Y. The mass of
90 Zr is 89.9329 amu. What is the
mass of
90 Y?
71. Discuss the principle and applications of a coincidence and anti-coincidence
type of counters. Considering the decay schemes, explain which counter you
would select to count
63 Ni and
38 Cl isotopes separately.
72. Why is a photomultiplier tube used in a scintillation counter? Can you replace
the photomultiplier tube with something to measure α-particles giving activity
1.05 cpm, but without using any other method of counting, i.e., proportional,
G.M., or solid-state counters?
73. Considering the decay scheme of
111 Ag, which counter will you select for counting this isotope in liquid form? Discuss by giving reasons for your selection of
the counter.
74. A sample of freshly prepared
90 Sr is provided to you. How will you count this
isotope and in which form would you prefer to measure the activity? Would you
prefer to count the sample immediately or after one week? Give reasons for your
choice. Explain the decay scheme of this isotope.
75. Find out the decay scheme of
42 K:
Which type of radiations emitted by this isotope would you prefer to use for
counting this isotope and why?
76. Suggest which counter you would prefer to count the following radioactive isotopes. Give reasons for your answer.
(a)
24 Na in solid form (E max ) for β-particles 1.39 MeV and 1.36 MeV, T 0.5 15 h.
(b) Uranium mixed with
24 Na in solid form.
(c) Tritium in the form of aqueous solution (E max ) for β-particles 0.018 MeV
T 0.5 12.35y. What considerations would you make if this isotope is to be
counted in solid form?
77. Why do α-decay and high energy nuclear reactions leave the parent atom in
an excited state, whereas β-decay, EC-decay, or I T -type decay do not? Would
you agree that in all the above cases, the daughter molecule will have a form
chemically different from the parent and if so, why?
78. Explain the various considerations you would make for counting an α-emitting
source and an energetic β-emitter source.
79. What do you understand by self-absorption? What will be its effect in counting
the radiation of a source emitting low energy β-particles?
229
68. Describe the recent developments in the detection and measurement of radiations. What is the smallest amount of
198 Au expressed in microcuries that you
can measure with ± 10% standard deviation? Assume that you are provided with
a well-type scintillation counter which gives an efficiency of 25.6%. Let each
counting be done for 10 minutes. The background count was 653 obtained in 10
min of counting.
69. Find out the decay scheme for
64 Cu:
The sample is present in a solid form. How will you prepare the source for
counting this isotope and which counter would you select for counting purposes?
Explain.
70. Find out the decay scheme of
90 Y. The mass of
90 Zr is 89.9329 amu. What is the
mass of
90 Y?
71. Discuss the principle and applications of a coincidence and anti-coincidence
type of counters. Considering the decay schemes, explain which counter you
would select to count
63 Ni and
38 Cl isotopes separately.
72. Why is a photomultiplier tube used in a scintillation counter? Can you replace
the photomultiplier tube with something to measure α-particles giving activity
1.05 cpm, but without using any other method of counting, i.e., proportional,
G.M., or solid-state counters?
73. Considering the decay scheme of
111 Ag, which counter will you select for counting this isotope in liquid form? Discuss by giving reasons for your selection of
the counter.
74. A sample of freshly prepared
90 Sr is provided to you. How will you count this
isotope and in which form would you prefer to measure the activity? Would you
prefer to count the sample immediately or after one week? Give reasons for your
choice. Explain the decay scheme of this isotope.
75. Find out the decay scheme of
42 K:
Which type of radiations emitted by this isotope would you prefer to use for
counting this isotope and why?
76. Suggest which counter you would prefer to count the following radioactive isotopes. Give reasons for your answer.
(a)
24 Na in solid form (E max ) for β-particles 1.39 MeV and 1.36 MeV, T 0.5 15 h.
(b) Uranium mixed with
24 Na in solid form.
(c) Tritium in the form of aqueous solution (E max ) for β-particles 0.018 MeV
T 0.5 12.35y. What considerations would you make if this isotope is to be
counted in solid form?
77. Why do α-decay and high energy nuclear reactions leave the parent atom in
an excited state, whereas β-decay, EC-decay, or I T -type decay do not? Would
you agree that in all the above cases, the daughter molecule will have a form
chemically different from the parent and if so, why?
78. Explain the various considerations you would make for counting an α-emitting
source and an energetic β-emitter source.
79. What do you understand by self-absorption? What will be its effect in counting
the radiation of a source emitting low energy β-particles?