ion ring lattice with -I sextupole pairs for ir chromaticity correction Y. Nosochkov, M-H. Wang 04-07-2015

Outline Use ion ring lattice v15c.0 04/07/2015 Outline Use ion ring lattice v15c.0 Generate optics with two –I sextupole pairs on either side of IP Make high beta functions at the –I sextupoles and set np phase advance from these sextupoles to the FFB Use other arc sextupoles for linear chromaticity correction Verify dynamic aperture

Upstream –I sextupole pairs 04/07/2015 Upstream –I sextupole pairs Generate high beta at –I sextupoles, set np phase advance from these sextupoles to FFB. Use 12 (X) + 12 (Y) arc sextupoles for linear chromaticity (12 cells make +I transformation for better compensation of arc sextupole aberrations). Y-sext IP X-sext

Downstream –I sextupole pairs 04/07/2015 Downstream –I sextupole pairs Same optics for downstream –I sextupoles as for the upstream sextupoles. Potentially, the upstream and downstream sextupoles may have different betas due to different FFB betas. Use 12 (X) + 12 (Y) arc sextupoles for linear chromaticity. X-sext Y-sext IP

04/07/2015 Complete ring optics Tune is not optimized: Q=[23.954, 23.153], x =[-111.1, -131.5]

04/07/2015 W-functions Adjust –I sextupole strengths for W=0 at IP, and the arc sextupole strengths for cancellation of linear chromaticity. K2 values (m-3): 0.411, -0.485 (upstream pairs), -0.828, 0.817 (downstream pairs), 0.509, -1.042 (arcs).

04/07/2015 Chromatic tune and b* Since the X-tune is too close to an integer resonance, it limits the energy range for negative Dp/p. Moving the tune away from this resonance should correct this problem.

Dynamic aperture using LEGO 04/07/2015 Dynamic aperture using LEGO Both on-energy and off-energy dynamic aperture improved relative to the original (not optimized) lattice with periodic arc sextupoles only. Note that the off-momentum range for Dp/p<0 is more limited due to the X-tune too close to an integer resonance.

04/07/2015 Backup slides

Beam dynamics properties of original “meic_p_ring_v15c.0” exN=0.35E-6, eyN=0.07E-6 No off momentum (>0.1%) aperture Amplitude dependent tune Amplitude tune Tune footprint Chromatic tune bx,ip=10 cm, by,ip=2 cm Qx = 24.38 Qy = 24.28