Physics 490: Project Lab

Radioactivity: Counting Statistics

Counting Statistics Team members:

Jack Young

Rich Breazeale

Ryan Phelan

Contents

Apparatus Experimental Procedure Analysis Conclusions Presentation: Radioactive Decay

Apparatus

Radioactive Sample

Geiger Counter

Science WorkshopInterface

Windows Stationw/ Science Workshop

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Radioactive DecayRadioactive Decay

What is radioactive decay?

Radioactive decay is the process by which atomic nuclei change.

There are four different ways this can happen.

Each ejects some particle from the nucleus – all but one create another element.

Alpha decay

Nucleus emits alpha particle – two protons and two neutrons.

Atomic number reduced by two. Number of nucleons reduced by four.

Alpha decay

Our example: U-238

92U238 90Th234 + alpha

Beta decay Neutron becomes a proton – emitting an electron and

an antineutrino. Z increases by one. Or, proton becomes a neutron – emitting a positron and

a neutrino. Z decreases by one.

Beta decay

Our examples: Co-60 and Tl-204

27Co60 28Ni60 + e- + antineutrino

81Tl204 82Pb204 + e- + antineutrino

Gamma decay

Energetic nucleus deexcites, emitting a photon (gamma ray).

All nuclear numbers remain unchanged. Nucleus in lower energy state after decay.

Chart of nuclides

Organizes nuclides according to atomic number Z and nucleon number N.

Contains other info: half-life, decay modes, etc.

Z

N

Chart of nuclides

Fin