Emittance limitation in cooled hadron beams

We identify an essential factor that limits the lowest achievable temperature of a stored hadron beam when it is cooled. Two different numerical techniques, i.e. the particle-in-cell and molecular dynamics methods, are employed to simulate the collective beam behavior in a storage ring. It is demonstrated that a cooling process can be strongly interrupted by linear and nonlinear resonance stopbands. In particular, a serious tune locking occurs when a second-order coherent resonance is encountered during cooling. We show that, in order to reach the space-charge limit by means of a strong dissipative force, the design phase advance per lattice period must be smaller than 90 degrees.