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 RadiationCan be stopped by a sheet of paperContains two protons and two neutronsIs the same as a helium-4 nucleusProduced by americium-241 and used

in smoke detectors

QuickTime™ and a decompressor

are needed to see this picture.

Beta Radiation

Is the equivalent of an electronBlocked by metal foilCan kill cancer cells (injected into

patient)Neutron spontaneous becomes a

proton, electron, and antineutrinoOnly the proton remains, the other two

are emitted (they are the radiation)

Beta Radiation Continued

Hydrogen-3 (tritium) undergoes beta decay

See video: http://science.howstuffworks.com/nuclear2.htm

Gamma Radiation

Emitted with alpha or beta radiationInvisible, high energy light10 cm of lead will stop gamma rays

completelyGamma tracers use gamma rays in low

doses to complete nuclear scans of the body

Gamma knife to treat cancer (not injected into patient)

Radiation SummaryThe 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 Particles Beta Particles High energy EM radiation

Description Helium nuclei Electrons Photons

Charge +2 −1 0

Symbol γ

Relative Penetrating Power

Blocked by Paper

Blocked by Metal Foil

Not completely Blocked by Lead or

Concrete

α42

42 ....orHe β0

101 .... −− ore

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)

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88222Ra → 2

4α + 86218Rn

Beta Decay

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

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614 C → 7

14N + -10β