Round beam collisions at vepp-2000
The idea of round-beam collision was proposed more than 20 years ago for the Novosibirsk Phi-factory design.  It requires equal emittances, equal small fractional tunes, equal beta functions at the IP, no betatron coupling in the collider arcs. Such an approach results in conservation of the longitudinal component of angular momentum. As a consequence, it yields an enhancement of dynamical stability, even with nonlinear effects from the beam-beam force taken into account. The Round Beam Concept (RBC) was realized at the electronpositron collider VEPP-2000 and successfully tested at the energy of 510 MeV.  Despite the low energy, a high single-bunch luminosity of 1031 cm -2s-1 was achieved together with a maximum tune shift as high as 0.1. At present the work is in progress to increase the energy of the collider to explore the range between 500 MeV and 1 GeV in collision. Copyright © 2011 by IPAC'11/EPS-AG.