Stafford Dissertation Introduction

The Neutrino

• An electromagnetic shower is initiated when a UHE neutrino traversing matter strikes an atomic nucleus, freeing high-energy electron and nuclear fragments. Liberated electrons scatter off atoms, emitting photons through bremsstrahlung. cf. Kaeli’s Dissertation Ch 1.3

• These photons in turn scatter against atoms, creating positron-electron pairs via pair-production, and freeing additional electrons via Compton scattering

• Subsequent bremsstrahlung emissions and positron-electron annihilations produce even more photons. A chain reaction ensures, and a conglomeration of positrons and electrons begins to accumulate.

• Compton electrons and positron annihilation leads to a negative charge excess of about 20% in the conglomeration.

• The cascade continues until the energy per \(e^{\pm}\) falls to about 100 MeV. At this point, ionization replaces bremstrahlung as the primary stopping mechanism and the shower ceases to develop.

• Neutrino mass: \(<10^{-6} \, m_e\)

• barn: \(10^{-28}\) m; mb: \(10^{-31}\) m.

• CC is deep inelastic. NC is elastic. (Figure 1.1 in the thesis)