Achievement of ultralow emittance coupling in the Australian Synchrotron storage ring

Abstract

Investigations into producing an electron beam with ultralow vertical emittance have been conducted using the Australian Synchrotron 3 GeV storage ring. A method of tuning the emittance coupling ( y = x ) has been developed using a machine model calibrated through the linear optics from closed orbits method. Direct measurements of the beam emittance have not been possible due to diagnostic limitations, however two independent indirect measurements both indicate a vertical emittance of 1.2-1.3 pm rad ( y = x ¼ 0:01%). Other indirect measurements support the validity of these results. This result is the smallest vertical emittance currently achieved in a storage ring.

Measurement of ultralow vertical emittance using a calibrated vertical undulator

“…IV. The vertical emittance ε yORM was evaluated using the matrix method of Chao [34], for lattices fitted by LOCO to measured orbit response matrices [24], with uncertainty expressing the standard deviation of vertical emittance fitted around the ring. Using this method, orbit response matrix measurements account only for betatron coupling and vertical dispersion contributions to the vertical emittance, which are normally the dominant contributions to vertical emittance.…”

“…Using the orbit response matrices fitted by LOCO [23], the strengths of skew quadrupole magnets were optimized for a range of vertical emittances, including the minimum emittance fitted by the optimization routine [24]. This model was used to define vertical emittance setpoints ϵ y .…”

Ultra low vertical emittance at SLS through systematic and random optimization

“…1. Vertical emittances of 1:6 pm rad and 1:2 pm rad have so far been reported from light sources [7,8]. It is stressed, however, that the emittance of the former result is obtained from beam size measurements while the latter result is estimated by using the Touschek lifetime.…”

Low-emittance tuning at the Cornell Electron Storage Ring Test Accelerator

“…In particular, LOCO has been used as the cornerstone for corrections at both the Swiss Light Source (SLS) and the Australian Synchrotron, where vertical emittances of order 1 pm have been reported [7,8].…”