1/2s & Energies

Question 1

What’s the T_1/2 of Co-60 and its average energy?

Answer 1

• Produced via neutron bombardment in a nuclear reactor
• T_1/2 = 5.26 yrs
• Decay: ⁶⁰₂₇Co → ⁶⁰₂₈Ni + e^- + anti-neutrino + γ rays
• Decay rate = 1% per mo
• Average energy: γ rays w/ 1.17 and 1.33 MeV (avg. 1.25)

Question 2

What is the decay equation for Co-60?

Answer 2

⁶⁰₂₇Co → ⁶⁰₂₈Ni + e^- + anti-neutrino + γ rays

Question 3

What’s the T_1/2 of Ra-226 and its average energy?

Answer 3

• T_1/2: 1622 yr
• Average energy: 0.83 MeV

Question 4

What’s the T_1/2 of Cs-131 and its average energy?

Answer 4

• T_1/2: 9.7 d
• Average energy: γ rays w/ 0.029 MeV

Question 5

What’s the T_1/2 of Cs-137 and its average energy?

Answer 5

• T_1/2: 30 r
• Average energy: γ rays w/ 0.662 MeV

Question 6

What’s the T_1/2 of Ir-192, its average energy, and how does it decay?

Answer 6

• T_1/2: 74.2 d
• Decay: β^- + γ (95%); e^- capture (5%)
• Average energy: γ w/ 0.38 MeV

Question 7

How much does Ir-192 decay per day?

Answer 7

1%/d

Question 8

What’s the T_1/2 of I-125, its mode of decay, and its average energy?

Answer 8

• T_1/2: 60 days
• Mode: E^- capture
• Energy: 28 keV

Question 9

What’s the T_1/2 Pd-103, its mode of decay, and its average energy?

Answer 9

• T_1/2: 17 d
• Energy: 22 keV

Question 10

What’s the T_1/2 I-131, its mode of decay, and its average energy?

Answer 10

• Made in a nuclear reactor
• T_1/2: 8.04 d
• Mode: decays into Xe; Releases e^- and γ
• Energy: e^- (0.192 MeV, range 1 mm); γ (364 keV)
  – e^- are used for tx
  – γ is used for imaging

Question 11

What’s the T_1/2 Y-90, its mode of decay, and its average energy?

Answer 11

• Made in a nuclear reactor
• T_1/2: 2.67 d
• Mode: Releases e^-
• Energy: e^- (0.192 MeV, range 1 mm); γ (364 keV)
  – e^- are used for tx
  – γ is used for imaging