Probing halfβy*optics in the Accelerator Test Facility 2

Design and Principles of Linear Accelerators and Colliders

“…There are two primary approaches for chromaticity compensation-the non-local scheme, implemented particularly at FFTB [74] and B-factories [75,76] and the local compensation Scheme [77] at ATF2 [78,79]. Further developments in optics with smaller vertical beam size and larger chromaticity are also being investigated at ATF2 [80,81] to explore the feasibility of the local compensation scheme at different chromaticity levels.…”

FCC-ee: Your Questions Answered

“…The two linear-collider final-focus test facilities FFTB (1994)(1995)(1996)(1997) and ATF2 (since 2009) achieved, after extended tuning periods, unprecedentedly small world-record spot sizes; yet the minimal vertical spot sizes were still about two to eight times larger than expected for the respective optics and measured input emittances [22,23,24]. The ATF2 spot size was decreased below 100 nm after reducing the bunch charge by five to ten and increasing β *…”

“…The reasons for, and the various contributions to, the larger-than-expected spot sizes at SLC, FFTB and ATF2 are not yet entirely understood [21,22,24]. Examples of large differences between expected and achieved beam sizes at FFTB, SLC, and ATF2 are shown in Fig.…”

“…Figure 4: Expected and typically achieved, or average, vertical rms spot sizes at the FFTB [22], SLC [21,26] and ATF2 [24,23,27] (left) and the ratio of the achieved and expected spot sizes (right).…”