Design of a low-emittance 2.5-GeV pohang light source lattice

The Pohang Light Source (PLS) storage ring is a synchrotron light source with the emittance of 18.9 nm at 2.5 GeV. We designed a new lattice with an achromat of the emittance of 13 nm that may provide more brilliant synchrotron radiation. We investigated dependence of the dynamic aperture on the betatron tune to search for large dynamic aperture in the low-emittance lattice by a simulation method. We examined the dynamic apertures by a tune survey within a specified tune space without and with machine errors. It is also shown that how large is the dynamic aperture in the storage ring after correction of a closed orbit distortion. The operating tune for the low-emittance lattice can be chosen on the view point of dynamic apertures obtained from a tune survey. The low-emittance lattice with the achromat shows the reduced horizontal and vertical beam sizes by 10% and 29% in the positions of insertion devices and by 31% and 52% in the bending magnets than the present lattice, respectively. It is also shown that the low-emittance lattice with 13 nm may provide sufficient dynamic aperture without changing of configuration of magnets in the storage ring.