Quantum Ground State and Minimum Emittance of a Fermionic Particle Beam in a Circular Accelerator

摘要

In the usual parameter regime of accelerator physics, particle ensembles can be treated as classical. If we approach a regime where ε_xε_yε_s ≈ N_(particles)λ_(Compton)~3, however, the granular structure of quantum-mechanical phase space becomes a concern. In particular, we have to consider the Pauli exclusion principle, which will limit the minimum achievable emittance for a beam of fermions. We calculate these lowest emittances for the cases of bunched and coasting beams at zero temperature and their first-order change rate at finite temperature.