Speaker
Description
Jefferson Lab is pursuing an upgrade to nearly double the beam energy of the Continuous Electron Beam Accelerator Facility (CEBAF) to 22 GeV, while maintaining high electron polarization. The upgrade’s cornerstone is a new pair of FFA arcs (Fixed Field Alternating Gradient) configured with Halbach style, combined-function permanent magnets, that would support simultaneous transport of additional 6 passes. Beam dynamics in the FFA arc is strongly dominated by synchrotron-radiation effects in both the transverse and longitudinal phase-spaces. As a result, accurate evaluation of polarization transport requires full multi-particle spin–orbit tracking. Preliminary simulations indicate only a small reduction in the polarization magnitude—within the expected 1-sigma resolution of typical polarization measurements—yet it reveals substantial changes in the spin orientation when synchrotron radiation is included. In addition to spin tune shifts, the betatron tunes are also notably modified due to radiation-induced energy oscillations. In this report, we present multi-particle tracking studies for the proposed FFA@CEBAF upgrade, focusing on spin transport and tune evolution both with and without synchrotron-radiation effects.
Funding Agency
This material is based upon work supported by the U.S. DOE, Office of Science, Office of Nuclear Physics contract DE-AC05-06OR23177.
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