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

2. 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

3. 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

4. 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

5. 04/07/2015
Complete ring optics
Tune is not optimized: Q=[23.954, ], x =[-111.1, ]

6. 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, (upstream pairs), , (downstream pairs), 0.509, (arcs).

7. 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.

8. 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.

9. 04/07/2015
Backup slides

10. 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