The anti-bend cell for ultralow emittance storage ring lattices

A small bending magnet of negative deflection, called anti-bend, can be used to reduce the equilibrium emittance of a periodic lattice cell by providing the proper matching of the dispersion function to the theoretical minimum emittance (TME) condition. With an anti-bend deflection angle of about −10% of the main bending magnet angle, a factor of 2 lower emittance can be achieved. Integration of horizontal focusing into the anti-bend leads to an economic half-quadrupole magnet design, which allows the damping partitions to be conveniently adjusted for further emittance reduction. The use of the anti-bend cell (ABC) is exemplified by the draft design of a compact storage ring with very low emittance and options for short pulse operation.