Radioactive Decay

Question 1

A parent decays to what?

Answer 1

a daughter

Question 2

Types of radioactive decay

Answer 2

1. Alpha Decay
2. Beta -
3. Beta +
4. Electron capture (EC)
5. Internal conversion (IC)

Question 3

Explain Alpha Decay

Answer 3

1. ‘A’ decreases by 4 (2 protons, 2 neutrons);
2. ‘Z’ decreases by 2;
3. Decays by same energy, every decay;
4. Mainly occurs in heavy elements, Z > 82;
5. Discrete energy (only 1 energy ranging from 5 - 10 Mev);
6. Carries a +2 charge;
7. Range of 4cm in air;
8. 5000 ion pairs/mm

Question 4

Explain Beta- Decay

Answer 4

1. Z + 1, N - 1;
2. Antineutrino released (electron);
3. NEUTRON rich parent;
4. PROTON deficient parent;
5. Avg is 1/3 of max (9Mev Max has 3Mev avg);
6. Daughter is an isobar
7. most B- is followed by gamma

Question 5

Explain Beta+ Decay

Answer 5

1. Z - 1, N + 1;
2. neutrino released (positron);
3. NEUTRON deficient parent;
4. PROTON rich parent;
5. Avg is 1/3 x .4
6. Daughter is an isobar;
7. E > 1.022 MeV Threshold due to annihilation photons, 0.511 MeV x 2 (similar to pair production);
8. Lighter elements

Question 6

Explain Electron Capture (EC)

Answer 6

1. it grabs an electron;
2. Z -1, N + 1;
3. PROTON rich parent;
4. E can be < 1.022 MeV;
5. heavier elements;
6. followed by characteristic x-rays or auger electrons

Question 7

Explain Internal Conversion (IC)

Answer 7

1. A, Z, n remain unchanged;
2. Transfers E from nucleus to orbital electron (K or L shell);
3. Discrete e’ is ejected;
4. Probability of occurrence increases with Z;
5. results in production of characteristic x-rays or auger electrons