1. Ion Path Length Compensation with Chicane
V. Morozov, P. Nadel-Turonski, M. Sullivan
MEIC R&D Meeting, JLab, May 29, 2014
F. Lin

2. Outline Naïve look Practical considerations Realistic estimate
Conclusions 2

3. Naïve Look
Triangular chicane with 20 m base and 1 m height  ~10 cm additional path length, solves some of the problem
Chicane with double the height  ~40 cm additional path length, solves the whole problem, looks attractive
1 m
20 m
2 m
20 m 3

4. Some Practical Considerations
Orbit curvature changes inside the dipoles  limit maximum sagitta R
Using
optimal curvature   4

5. Realistic Estimate
Assume each dipole is 3 m long and bends by 50 mrad and require 40 cm path length increase
4 dipoles
8 dipoles
12 dipoles
16 dipoles 5

6. Realistic Estimate
Consider solving half the problem, 20 cm path length increase
4 dipoles
8 dipoles
12 dipoles 6

7. Conclusions
Naïve estimate looks attractive but, because of the finite dipole lengths, a realistic chicane comes out much longer.
12 dipole case seems best but the chicane length is still 66 m with the maximum orbit deviation of about 3.25 m.
A chicane would solve a lot of problems though
No orbit shifts in either collider ring
No change of electron SRF frequency (ion SRF still has to accommodate harmonic jumps)
No CEBAF synchronization problem
Conceptually simple, almost no additional R&D needed  easier to convince reviewers that it will work?
Easier to cost?
Is such a chicane realistic? 7