Nuclear Decay

What is Radiation? Radiation is the rays and particles emitted by radioactive material Radioactive decay - the process by which unstable nuclei lose energy – Types of decay are alpha particles, beta particles, and gamma rays

The three types of radiation

Alpha Radiation Can be stopped by a sheet of paper Contains two protons and two neutrons Is the same as a helium-4 nucleus Produced by americium-241 and used in smoke detectors

Beta Radiation Is the equivalent of an electron Blocked by metal foil Can kill cancer cells (injected into patient) Neutron spontaneous becomes a proton, electron, and antineutrino Only the proton remains, the other two are emitted (they are the radiation)

Beta Radiation Continued Hydrogen-3 (tritium) undergoes beta decay See video: ar2.htm ar2.htm

Gamma Radiation Emitted with alpha or beta radiation Invisible, high energy light 10 cm of lead will stop gamma rays completely Gamma tracers use gamma rays in low doses to complete nuclear scans of the body Gamma knife to treat cancer (not injected into patient)

Radiation Summary The three most common types of radiation are alpha (α), beta (β), and gamma (γ). Type of Radiation Alpha (α) Beta (β)Gamma (γ) Composition Alpha ParticlesBeta Particles High energy EM radiation Description Helium nucleiElectronsPhotons Charge+2−10 Symbol γ Relative Penetrating Power Blocked by Paper Blocked by Metal Foil Not completely Blocked by Lead or Concrete

Nuclear Decay Equations New elements are often produced by nuclear decay Types of decay that produce new elements: – Alpha – Beta

Alpha Decay Atom’s nucleus emits an alpha particle (2 protons and 2 neutrons)

Beta Decay Atom’s nucleus emits a beta particle (1 electron)