20 Questions
Who discovered the X-rays in 1895?
W.C. Röntgen
In which country did the first X-ray machine arrive two years after the discovery of ionizing radiation?
Malaysia
What is the name of the center established under the PM Dept. in 1972 for research and application in nuclear energy?
CRANE
What is the term used to describe the emission and transmission of energy through space, including charged and uncharged particles as well as electromagnetic radiation?
Radiation
Which type of radiation contributes the most to the average yearly global radiation dose?
Gamma radiation
What is the primary source of natural radiation contributing to the global yearly radiation dose?
Cosmic rays
What is the primary manmade source of ionising radiation?
Medical purposes
What is the unit for absorbed dose of ionising radiation?
Gy
What determines the identity and atomic mass of an element?
The number of protons
What are atoms of the same element with different numbers of neutrons called?
Isotopes
What is the spontaneous emission of ionizing radiation from unstable nuclides called?
Radioactivity
What do stable nuclides have that leads to nuclear stability?
Correct balance of neutrons and protons
Which process involves a photon transforming into matter in the form of an electron and a positron?
Pair production
What is the process called where a photon collides with an atomic electron and only partially transfers its energy?
Compton scattering
Which type of radiation includes natural radiation, cosmic and terrestrial, and man-made radiation from nuclear weapons, power plants, and consumer goods?
Ionizing radiation
What is the total ionizing dose to a population, weighted by the radiation type and the tissue or organ at risk called?
Effective dose
Which type of radiation is known for causing ionization when passing through matter?
Neutrons
What is the specific activity a measure of?
Activity per unit mass
Which radionuclide has the longest half-life among the given examples?
Potassium-40 (40K)
Which of the following is a high-Z material used for shielding against photons?
Lead
Study Notes
- Activity: 3 radioactive decay modes (beta & gamma) with different disintegration rates.
- Disintegration rate: Measured in Becquerel (Bq), 1 Bq = 1 dps (s-1), or Curie (Ci). Old unit.
- Specific activity: Activity per unit mass, Bq/g.
- Decay law: Activity reduction over time, governed by decay constant (l) and half-life (T1/2).
- Half-life: Specific time for a radionuclide's activity to reduce by half. Various radionuclides have different half-lives.
- Strontium-90 (90Sr): Half-life 28.5 years, decays by beta decay.
- Caesium-137 (137Cs): Half-life 30.1 years, decays by beta decay.
- Radium-226 (226Ra): Half-life 1600 years, decays by alpha decay.
- Carbon-14 (14C): Half-life 5736 years, decays by beta decay.
- Potassium-40 (40K): Half-life 1.28 x 10^8 years, decays by beta decay.
- Activity calculation: Co-60 (100 kCi) has a half-life of 5.27 years. After 5 years, the remaining activity would be approximately 51.81 kCi.
- Radionuclides chart: Contains different nuclides, their decay modes (alpha, beta, gamma), half-lives, and thermal neutron capture cross sections.
- Ionizing radiation: Radiation that causes ionization when passing through matter, including alpha particles, beta particles, gamma rays, neutrons, and positrons.
- Alpha particles: Helium nuclei, high mass and charge, high energy, short range, and an important internal hazard.
- Beta particles: High-speed electrons, continuous energy distribution, produce ionization and excitations, and can be either positrons or electrons.
- Gamma rays: Electromagnetic radiation from excited nuclei or orbits, long range, external hazard, and not a great internal hazard.
- Shielding: Use high-Z materials to shield against photons and low-Z materials to protect against beta particles.
- Interactions: Photoelectric effect, Compton effect, and pair production, all increasing with Z and producing characteristic X-rays and bremsstrahlung X-rays.
Test your knowledge on radioactivity, half-life, and decay laws with this quiz. Questions cover topics such as disintegration rate, specific activity, and the fraction of activity left after a certain number of half-lives.
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