| Paper | Title | Page |
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| TUPEB044 | Spin Rotator Optics for MEIC | 1626 |
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A unique design feature of a polarized Medium Energy Electron-Ion Collider (MEIC) based on CEBAF is its 'Figure-8' storage rings for both electrons and ions, which significantly simplifies beam polarization maintenance and manipulation. While electron (positron) polarization is maintained vertical in arcs of the ring, a stable longitudinal spin at four collision points is achieved through solenoid based spin rotators and horizontal orbit bends. The proposed MEIC lattice was developed in order to preserve a very high polarization (more than 70%) of the electron beams injected from the CEBAF machine. The otherwise coupled beam trajectory due to solenoids used in the spin rotators was decoupled by design. Aspin matching technique needs to be implemented in order to enhance quantum self-polarization and minimize depolarization effects. |
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| TUPEB045 | Correction of the Chromaticity up to Second Order for MEIC | 1629 |
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The proposed electron collider lattice exhibits low β- functions at the Interaction Point (IP) (βx∗100mm − βy∗ 20 mm) and rather large equilibrium momentum spread of the collider ring (δp/p = 0.00158). Both features make the chromatic corrections of paramount importance. Here the chromatic effects of the final focus quadruples are cor- rected both locally and globally. Local correction features symmetric sextupole families around the IP, the betatron phase advances from the IP to the sextupoles are chosen to eliminate the second order chromatic aberration. Global interleaved families of sextupoles are placed in the figure-8 arc sections, and non-interleaved families at straight sec- tion making use of the freely propagated dispersion wave from the arcs. This strategy minimizes the required sex- tupole strength and eventually leads to larger dynamic aper- ture of the collider. The resulting spherical aberrations induced by the sextupoles are mitigated by design; the straight and arc sections optics features an inverse identity transformation between sextupoles in each pair. |