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 Workshop Interface Windows Station w/ Science Workshop

Frequency

Frequency (thousands)

Radioactive 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 U 238  90 Th 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 Co 60  28 Ni 60 + e - + antineutrino 81 Tl 204  82 Pb 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