Workshop Summary (presented at PSTP '07, BNL, 9/14/07)
Working Group Update (presented at EIC Collaboration Meeting in Stony Brook, 12/8/07)

EIC Lattice Design for Interaction Regions

ELIC

a)

Figure-8 Electron Ring – Small Equilibrium Emittance Lattice
Figure-8 Ion Ring – Minimum Dispersion Lattice
2005 Particle Accelerator Conference Proceedings

Note,

1. that these are "old" optics design, a major revision are currently underway.
2. The following changes of optics are expected in the new optics:
   • change figure-8 ring circumference from 1.2 km (the latest design) to 1.4 km (our baseline)
   • re-configuration of IP final focusing magnets (for reducing crossing angles)
   • incorporating new scheme for chromatic mitigation with sextupoles
   • accommodation of insertion elements such as spin rotators, snakes, etc
3. the new optics should be available in 3 to 4 weeks time frame

b)

Figure-8 Ring design (ps)
electron_Ring (mad), (TWISS)

Note,

1. this is the latest optics design (Feb 2008)
   

eRHIC

ring-ring lattice

Note,

1. this a "twiss" file that describes the eRHIC ring-ring lattice; however, this version still has innermost IR magnets at 1m from the IP, not 3m. I don't think a version with magnets at 3m exists yet.
2. If you are unfamilar with the format of these files, here is a quick explanation
   • the file is made up of blocks of 5 lines each, beginning with the element name. The first four characters of the element name indicate the element type, e.g. "DRIF" for drifts, "QUAD" for quadrupoles, "RBEN" or "SBEN" for dipoles, etc
   • the second entry on the first line of each block is the element length, in meters.
   • the third entry depends on the element type; in case of an "RBEN" or "SBEN", it's the bending angle.
   • the fourth entry is the quadrupole strength ("k-value"); note that this maybe non-zero even in dipoles, thus making them combined-function magnets.
   • line 3 gives you the horizontal Twiss-parameters, alpha_x, beta_x, phi_x, D_x (dispersion), and Dp_x (slope of dispersion).
   • line 4 contains the corresponding values for the vertical plane.