title: Anisotropic free-energy limit of halos in high-intensity accelerators.
abstract: We study halo emittance growth in anisotropic beams and show that the rms emittance growth resulting from mismatch is highly anisotropic, depending on the tune ratio. We find that the free-energy limit calculated by Reiser [J. Appl. Phys. 70, 1919 (1991)] for an axisymmetric 1D halo can be extended to 2D if understood as an upper bound to the rms emittance growth averaged per degree of freedom. The thus-obtained "free-energy limit" of an ideal transport system is compared with the halo rms emittance growth in simulations of the Spallation Neutron Source linac.
authors.affiliation: GSI Darmstadt, Planckstrasse 1, 64291 Darmstadt, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Franchetti
authors.forename: I
authors.initials: I
authors.lastname: Hofmann
authors.forename: D
authors.initials: D
authors.lastname: Jeon