CEPC Injector Linac beam dynamics CEPC regular meeting

CEPC Injector Linac beam dynamics CEPC regular meeting 2017/6/16 C. Meng , Y. Chi, G. Pei, J. Zhang, X. Li, S. Pei, J. Gao Institute of High Energy Physics, CAS, Beijing

Introduction • Linac goal • Simple and reliable • High availability • Linac is “inexistent” for collider Running • Always providing beams to meet the requirements Main parameters of CEPC Linac Parameter Symbol Unit Value e- /e+ beam energy Ee-/Ee+ Ge. V 10 Repetition rate frep Hz 50 100 e- /e+ bunch population Ne-/Ne+ >6. 25× 109 n. C Energy spread (e- /e+ ) σE Emittance (e- /e+ ) εr >1. 0 <2× 10 -3 mm mrad <0. 3 e- beam energy on Target Ge. V 4 e- bunch charge on Target n. C 10

Introduction Layout of Linac (II) LTB 10. 0 Ge. V S-band accelerating tube • 2856. 75 MHz

Linac design Main elements Type No. Value KLY 71 80 MW S-band Acc. Tube 1 265 18 MV/m 21 MV/m 8 2 1 ~25 m 48 213+~30 (ELBP) 18 MV/m 142. 8375/571. 35 MHz 2856. 75 MHz 0. 5 T r ~40 mm r ~20 mm S-band LAS Acc. Tube SHB Buncher Solenoid Quadrupole Larger Aperture Quadrupole Dipole ~ 10

Linac design Positron linac • 3. 2 n. C • 10 Ge. V Beam dynamics results (I)

Linac design Positron linac • 3. 2 n. C • 10 Ge. V • Beam loss Beam dynamics results (II)

Linac design Electron linac • 10 n. C • 4 Ge. V • Small beam size for positron production • 0. 5 mm Beam dynamics results (III)

Linac design • Simulation condition • 10 k particles • 100 seeds • Dynamic errors: Errors study • Simulation results • If rms beam obit (dynamic) <0. 1 mm, the dynamic alignment <2 μm • If rms beam obit (dynamic) <0. 2 mm, the dynamic alignment <5 μm • Quadrupole transverse alignment： 2 μm、5 μm、10 μm • Uniform distribution

Linac design Simulation condition • 10 k particles • 100 seeds • Dynamic errors: • Quadrupole transverse alignment： 0. 1 mm • Uniform distribution Errors study

Linac design With correction

Emittance without correction

Emittance with correction