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Discussion on dynamic aperture optimization at LNF-INFN, Italy, involving nonlinear correctors, kinematics, and fringe compensators. Evaluation of sources, tune amplitude dependence, and perturbations for optimal performance.
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2nd SuperB Collaboration Meeting 13 December 2011, LNF INFN, Frascati, Italy SuperB Factory:The Dynamic Aperture E.Levichev, P.Piminov , S.Sinyatkin, BINP SB RAS, Novosibirsk, Russia P.Raimondi, LNF-INFN, Frascati, Italy
Main Ring Layout FF Spin Rotator 3 ID cells 3 ID cells Injection section RF section
Arc Unit Cell Low emittance unit cell with twice interleave sextupoles -I
Interaction Region IP Horizontal Chromatic Sexts Vertical Chromatic Sexts Final Focus SDY0 SFX0 Crab Sexts
Main Nonlinear Sources • Kinematic Terms • FF Quadrupole Fringe Fields • Chromatic Arc Sextupoles • Strong IR Sextupoles • Crab Sextupoles
Comparison with MAD-8 We with Pantaleo compared the dynamic aperture and phase space trajectories for the following sources And found good agreement between MAD-8 and Acceleraticum. Tune amplitude dependence was compared with MADX and MAD-8 (Antoine Chancé) for different perturbations and good agreement was found. • Sextupoles • Octupoles • Quadrupole Fringe Fields • Kinematic term
Additional Nonlinear Correctors For the dynamic aperture optimization we used the following nonlinear correctors. Kinematics and Fringes Compensators (Oct) Octupoles in FF IR Sexts Compensators (Sext) Crab Compensators (Sext)
On Energy Dynamic Aperture The dynamic aperture of ideal lattice but with all perturbations Crab Sexts are switched on
Crab Sexts Influence Unfortunately switching on the crab sextupoles (even thin!) drastically reduces the dynamic aperture down. All nonlinearities All w/o Crab Sexts All w/o Kinematics and Fringes Kinematics and fringes break the –I condition at high amplitude.
Betatron Tune Scan Vertical DA vs tune point Horizontal DA vs tune point Working point is Qx=0.575 & Qz=0.595
Summary • Dynamic aperture for HER was studied for different nonlinear sources. • DA was optimized in the working point Qx=0.575 & Qz=0.595. • DA for present ideal lattice (25 x & 200 z) is enough to get a required luminosity and injection. • First version of the DA tune scan was performed that provides a possibility of better tune point definition.
Plans • Additional nonlinear correctors should be installed to into the lattice. • Compensation of interaction of Crab Sexts with Kinematics & Fringes should be found. • Energy acceptance optimization is needed. • We should try to find good solution for the dynamic aperture and the energy acceptance for the best working point luminosity (Qx=0.53, Qz=0.57). • Optimization of LER is similar. • Estimate of errors & misalignments influence on the dynamic aperture is needed.