1. Operated by the Jefferson Science Associates for the U.S. Depart. Of Energy Thomas Jefferson National Accelerator Facility Alex Bogacz, Acceleration in RLAs – Design Choices ISS Workshop, UC Irvine, August 21, 2006. Alex Bogacz ‘Racetrack’ vs ‘Dogbone’ configuration multi-pass linacs focusing orbit separation simultaneous acceleration of both  +  - species 10 GeV Two-step-Dogbone RLA Quadrupole focusing scheme – Triplet vs FODO lattices multi-pass linac matching to the Arcs vertical injection double-chicane Acceleration in RLAs – Design Choices

2. Operated by the Jefferson Science Associates for the U.S. Depart. Of Energy Thomas Jefferson National Accelerator Facility Alex Bogacz, Acceleration in RLAs – Design Choices ISS Workshop, UC Irvine, August 21, 2006. ‘Racetrack’ vs ‘Dogbone’ RLA (n-pass)  E/2 total arc length: (2n - 1)  R  E/2 EE n arcs n - 1 arcs E0E0 E 0 + n  E total arc length: 2n (7/6)  R n/2 droplets E 0 + (n + ½)  E E0E0 mis- focusing factor: 1 + (n-1)  E/E 0 mis- focusing factor: 1 + n  E/E 0 orbit separation factor: [E 0 + n  E]/[E 0 + (n-1)  E] ≃ n/n-1 orbit separation factor: [E 0 + (n+½)  E]/[E 0 + (n-2+½)  E] ≃ n/n-2

3. Operated by the Jefferson Science Associates for the U.S. Depart. Of Energy Thomas Jefferson National Accelerator Facility Alex Bogacz, Acceleration in RLAs – Design Choices ISS Workshop, UC Irvine, August 21, 2006. ‘Racetrack’ vs ‘Dogbone’ RLA (both  + and  - species )                

4. Operated by the Jefferson Science Associates for the U.S. Depart. Of Energy Thomas Jefferson National Accelerator Facility Alex Bogacz, Acceleration in RLAs – Design Choices ISS Workshop, UC Irvine, August 21, 2006. ‘Racetrack’ vs ‘Dogbone’ RLA (both  + and  - species )          

5. Operated by the Jefferson Science Associates for the U.S. Depart. Of Energy Thomas Jefferson National Accelerator Facility Alex Bogacz, Acceleration in RLAs – Design Choices ISS Workshop, UC Irvine, August 21, 2006. 10 GeV Two-step-Dogbone RLA 0.9 GeV to 3.0 GeV 3.0 GeV to 10 GeV 3.33… ext/inj energy ratio 0.9 GeV 0.2 GeV 1.5 GeV to 5.0 GeV 0.6 GeV/pass 3 GeV 2 GeV/pass 10 GeV

6. Operated by the Jefferson Science Associates for the U.S. Depart. Of Energy Thomas Jefferson National Accelerator Facility Alex Bogacz, Acceleration in RLAs – Design Choices ISS Workshop, UC Irvine, August 21, 2006. 10 GeV Two-step-Dogbone RLA 0.9 GeV to 3.0 GeV 3.0 GeV to 10 GeV 3.33… ext/inj energy ratio 0.9 GeV 0.2 GeV 1.5 GeV to 5.0 GeV 0.6 GeV/pass 3 GeV 2 GeV/pass 10 GeV

7. Operated by the Jefferson Science Associates for the U.S. Depart. Of Energy Thomas Jefferson National Accelerator Facility Alex Bogacz, Acceleration in RLAs – Design Choices ISS Workshop, UC Irvine, August 21, 2006. Injection double-chicane      

8. Operated by the Jefferson Science Associates for the U.S. Depart. Of Energy Thomas Jefferson National Accelerator Facility Alex Bogacz, Acceleration in RLAs – Design Choices ISS Workshop, UC Irvine, August 21, 2006. FODO vs Triplet focusing structure FODO  The same length  The same phase advance per cell (  x = 90 0 =  y ) Triplet Advantages: much weaker quads (~3 times) shorter quads (total) easier chromaticity correction Advantages: longer straight sections smaller vertical beta-function uniform variation of betas and dispersion

9. Operated by the Jefferson Science Associates for the U.S. Depart. Of Energy Thomas Jefferson National Accelerator Facility Alex Bogacz, Acceleration in RLAs – Design Choices ISS Workshop, UC Irvine, August 21, 2006. Multipass linac - Triplet vs FODO focusing (90 0 phase adv/cell) 1-pass 2-pass 3-pass

10. Operated by the Jefferson Science Associates for the U.S. Depart. Of Energy Thomas Jefferson National Accelerator Facility Alex Bogacz, Acceleration in RLAs – Design Choices ISS Workshop, UC Irvine, August 21, 2006. Straight-Arc  P eriodic transition Triplet FODO

11. Operated by the Jefferson Science Associates for the U.S. Depart. Of Energy Thomas Jefferson National Accelerator Facility Alex Bogacz, Acceleration in RLAs – Design Choices ISS Workshop, UC Irvine, August 21, 2006. Summary ‘Dogbone’ RLA – preferred configuration (compared to the ‘Racetrack’) better orbir separation for higher passes more efficient use of the rf (extra half-pass) offers symmetric solution for simultaneous acceleration of  + and  - FODO lattice more favorable (compared to the triplet) to accommodate large number of passes uniform phase advance decrease in both planes smaller variation of Twiss function – easier match to the Arcs allows to maintain 90 0 phase advance per cell for lowest passes Proposed 10 GeV two-step-dogbone RLA (30 mm rad acceptance) 3.0-10GeV ‘dogbone’ with 400MHz SRF? Needed: front-to-end simulation, magnet error/misalignment sensitivities etc.