Path Length Chicane Options V. Morozov, A. Hutton, P. Nadel-Turonski, M. Sullivan MEIC R&D Meeting, JLab, June 5, 2014 F. Lin

Outline Path length chicanes in arcs Path length chicane in straight 2

Concept of “Arc” Chicane Reserve space for two extra dipoles in each arc, otherwise regular arc lattice 3 m long dipoles separated by 1.68 m distances with 0.5 m long quadrupoles in between Arc bending angle is fixed (i.e. incoming and outgoing angles are fixed) and cord length is fixed (i.e. the coordinates of the arc ends are fixed) Two extremes of a 10 dipole arc Longest orbit: two dipoles at arc ends are off Shortest orbit: two dipoles in the middle of the arc are off Intermediate cases: the end and middle dipoles are partly powered 3

Geometry & Optics of “Arc” Chicane Long configuration 59 cm between dipoles and quads, example optics matched to regular FODO Short configuration 57.9 cm between dipoles and quads, example optics matched to regular FODO Path length difference of 200.9 mm Need two chicanes, one per arc, helps with simultaneous synchronization of two IPs Maximum total transverse movement of “only” 97 cm May fit in the regular tunnel 4

Full “Straight” Chicane 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

Half of “Straight” Chicane Consider solving half the problem, 20 cm path length increase 4 dipoles 8 dipoles 12 dipoles 6

Conclusions Arc chicane Straight chicane 44.7 m long but most of it is occupied by existing arc bending dipoles Each chicane provides 20 cm path length increase, need one in each arc but helps with simultaneous synchronization at two IPs Spacing between dipoles and quadrupoles changes from 57.9 to 59 cm Maximum total transverse movement of 97 cm, may fit in regular tunnel Requires movement of 8 dipoles and 9 quadrupoles per chicane Requires two extra dipoles and two extra quadrupoles per arc, total extra length < 20 m Straight chicane 66 m long, perhaps with some usable space but takes up straight space Maximum total transverse movement of 3.25 m Single 40 cm chicane is more economical in terms of space Considered making bending regions achromatic but requires strong quadrupoles and/or significant additional space Did not seem worth pursuing much further because because of the arc chicane option A chicane may not be an elegant solution but it does solve a lot of problems No orbit shifts in either collider ring No change of SRF frequency in either ring No CEBAF synchronization problem Conceptually simple, no additional R&D  easier to convince reviewers that it will work? Easier to cost? 7