Quantum Flavordynamics

Problems

practice

1. Two related problems in solar physics…
   1. How many solar neutrinos pass through your fingernail every second?
   2. How many solar photons land on your finger every second when you are in direct sunlight?
2. Write something.
3. Write something.
4. Write something.

conceptual

1. A tau lepton decays into an electron, an electron antineutrino, and a tau neutrino.
   1. Write out this reaction in symbolic form.
   2. Show that charge is conserved in this reaction.

investigative

1. Read this passage about the IceCube Neutrino Observatory in Antarctica.

   The neutrinos' feeble interaction with matter makes them powerful messengers of new physics, but it also complicates their detection. For example, the IceCube neutrino observatory in Antarctica relies on catching the flashes of Cherenkov light from muons produced by neutrinos inside a billion tons of ice. The 1 km³ observatory requires an array of more than 5000 photomultiplier tubes because the flux of ultrahigh-energy neutrinos is so small and plummets with neutrino energy. The highest-energy neutrinos IceCube ever measured are a few peta-electron volts (1 PeV = 10¹⁵ eV).

   How energetic is such a neutrino? One joule is about 10¹⁹ eV, roughly equivalent to the energy of a slow-pitched baseball. At one-thousandth of a joule, 10 PeV is the kinetic energy equivalent of a honeybee in flight. But whereas the honeybee's energy is distributed over some 10²³ atoms, extreme astrophysical events concentrate the energy in a single cosmic neutrino. To have much chance of catching one, you need to increase the search volume or change methods.

   R. Mark Wilson, 2020

   Verify the claims that…

   1. the kinetic energy of a slow pitched baseball is about one joule
   2. the kinetic energy of a honeybee in flight is about one petaelectronvolt