David Argento The nuclear underpinnings of Cosmogenic Nuclides David Argento

Outline Atomic and particle basics –Atomic structure –Major groups of subatomic particles Nuclear forces, structures and processes –Four primary forces –Radioactivity –Forms of radiation

David Argento Before we launch David Argento –Graduate student –JHN423 References –Hyperphysics: –Wickipedia: useful, but be very skeptical –Hundreds of papers Apologies for errors, omissions, over simplicity, over complication, and pace.

David Argento The Atom electron proton neutron

David Argento Quarks

David Argento Subatomic Particle Families & Generations

David Argento Back to the nucleus What happens with similar charged objects? m m F E = ~100N F G = ~ N

David Argento Forces ForceRangePrimary source/ interaction GravityInfiniteMass ElectromagneticInfinitecharge Weak nuclear~ m W and Z bosons, neutrinos and quarks Strong Nuclear~ mGluons and nucleons

David Argento Nuclear Stability The nucleus is stable in specific proton and neutron combinations Stability is based on electric-nuclear force balance Unstable nuclei will decay to achieve stability Eject energy, electrical charge and nucleons (protons and neutrons) Thus…

David Argento Radioactivity Gamma radiation –Electromagnetic radiation Alpha radiation –Helium nucleus Beta radiation –Electron or positron Neutrons Neutrinos Fission

David Argento Gamma Radiation Electromagnetic Radiation

David Argento Alpha radiation Energetic ejection of helium-4 in 2+ state (no electrons)

David Argento Beta Radiation Energetic ejection of electron or positron

David Argento Neutrons Ejection of neutrons (low to high energy) Can also accompany other decay modes

David Argento Neutrinos Weakly interacting, extremely small mass, and accompanies most, radioactive decay Not important for this the purpose of this class, but there is promise for use as probe of the interior of the earth (McDonough, W. F., Mapping the interior of the Earth, Science, 31, August 2007, pp )

David Argento Fission Not important for this class, but an important aspect of radioactive decay In-situ neutron source, must be corrected for if fissile material is present

David Argento Probability and the Half life Each and every atom of an isotopic species has the same probability of decaying during a period of time. This results in a set fraction of the population decaying in the same time period, regardless of total population Each isotope is different

David Argento Decay Curve

David Argento Modeling exponential decay

David Argento Population change Take the derivative: