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WEPOMS056 | Spin Matching and Monte-Carlo Simulation of Radiative Spin Depolarization in e+e− Storage Rings with Bmad | 2383 |
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Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under Award Numbers DE-SC0018008 and DE-SC0018370. The Bmad/Tao software toolkit has been extended to estimate the rate of radiative spin depolarization in e+/e− storage rings. First estimates are made using the SLIM algorithm of linearized spin-orbit motion. The extension implements the effects on s-o motion of stochastic photon emission using a Monte-Carlo tracking algorithm. Spins are tracked in 3-D along particle trajectories with the aid of Taylor expansions of quaternions provided by PTC*. The efficiency of long-term tracking is guarantied by the use of a sectioning technique that was exploited in previous-generation software**. Sectioning is the construction of the deterministic s-o maps for sections between the dipoles during the initialization phase. Maps can be reused during the tracking. In a simulation for a realistic storage ring, the computational cost of initial map construction is amortized by the multi-turn tracking computational cost. The use of 1st-order terms in the quaternion expansions to construct the s-o coupling matrices in the matrices of the SLIM algorithm. These matrices are then available for an extension of the optimization facilities in Bmad to minimize depolarizing effects by spin matching. *SLICKTRACK and SITROS ** Polymorphic Tracking Code by Etienne Forest |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS056 | |
About • | Received ※ 08 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 08 July 2022 | |
Cite • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |