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.
OPTIMIZATION OF LOW EMITTANCE LATTICES FOR PETRA III
The reconstruction of the existing 2.3 km long storage ring PETRA II into a 3rd generation synchrotron light source (PETRA III) calls for an horizontal emittance of 1 nm rad. In addition the on- and off-momentum dynamic acceptance should be large to ensure sufficient injection efficiency and beam lifetime. We present three different types of lattices for the arcs of PETRA: a so-called TME lattice and a FODO lattice which both are newly designed to reach the specified emittance and the present FODO lattice with damping wigglers. The different lattice types have been compared through tracking calculations, including wiggler nonlinearities. Only the relaxed FODO lattice with damping wigglers meets the acceptance goals.
Women and Politics in Early Tudor England
Political historians working on the early Tudor period have traditionally concentrated on institutions – monarchy, council, parliament, courts, and administrative bodies – that excluded women. The very definition of politics underlying the dominant historiography has thus made it seem both natural and inevitable to write history as if the world of high politics, the world that really counted, were exclusively male.