Crab Waist Collisions in Daφne and Super-b Design

The new idea of increasing the luminosity of a collider with crab waist collisions and first experimental results from the DAΦNE Φ-Factory at LNF, Frascati, using this concept are presented. Consequences for the design of future factories will be discussed. An outlook to the performance reach with crab waist collisions is given, with emphasis on future B Factories. INTRODUCTION A novel collision scheme, the “large Piwinski angle and crab waist” [1,2] has been studied, which will allow to reach unprecedented luminosity with low beam currents and reduced background at affordable operating costs. The principle of operation of this scheme is under test at the DAΦNE Frascati Φ-Factory [3]. The scheme finds its natural application to the SuperB project [4] aims at the construction of a very high luminosity (10 cm s) asymmetric (4 on 7 GeV) ee Flavour Factory with possible location at the campus of the University of Rome Tor Vergata near the INFN Frascati National Laboratory. A Super-B Conceptual Design Report (CDR) [5] was issued in May 2007. LARGE PIWINSKI ANGLE AND CRAB WAIST CONCEPT The Crab Waist scheme of beam-beam collisions can substantially increase collider luminosity since it combines several potentially advantageous ideas. Figure 1: Collision scheme with large Piwinski angle and crabbing sextupoles. The first one is large Piwinski angle. For collisions under a crossing angle θ the luminosity L and the horizontal ξx and vertical ξy tune shifts scale as (see, for example, [6]):