Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility Alex Bogacz NuFact’08, Valencia, Spain, July 4, 2008 Acceleration Scenario – IDS Baseline Linear Pre-accelerator (244 MeV to 900 MeV) RLA I  4.5 pass, 0.6 GeV/pass, (0.9 GeV to 3.6 GeV ) RLA II  4.5 pass, 2 GeV/pass (3.6 GeV to 12.6 GeV ) Non scaling FFAG (12.6 GeV to 25 GeV )

Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility Alex Bogacz NuFact’08, Valencia, Spain, July 4, GeV/pass 3.6 GeV 0.9 GeV 244 MeV 146 m 79 m 2 GeV/pass 264 m 12.6 GeV Towards Engineering Design Foundation

Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility Alex Bogacz NuFact’08, Valencia, Spain, July 4, 2008 Benefits/Pros. Large Acceptance Transverse (norm): 30 mm rad Longitudinal (norm): 150 mm momentum spread:   p/p = 0.07 bunch length:  z = 176 mm Synchrotron oscillations induced  full synchrotron period along the linac Correction of energy gain across the bunch (initial bunch-length: 89 0 rf) Significant longitudinal compression   p/p : 0.07  0.03 Challenges/Cons. Reduced effective acceleration grad. (825MeV RF vs 665MeV energy gain) One 1-cell cavity cryo-moduls in front Far off-crest acceleration; initially 74 0 Three different styles of cryo-modules Magnetic shielding of the SRF cavities Individual rf phase control for each cavity Linear Pre-accelerator (244 MeV MeV)

Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility Alex Bogacz NuFact’08, Valencia, Spain, July 4, 2008 Two-step ‘Dogbone’ RLAs (0.9  3.6  12.6 GeV) Benefits/Pros. Effective usage of high gradient SRF RLA I: 4.5 pass through 0.6 GeV linac RLA II: 4.5 pass through 2 GeV linac Individual return Arcs for each pass Path-length adjustment after each pass through the linac Further longitudinal rf compression Adjustable gang phase for each pass Nonzero momentum compaction in the Arcs (M 56 = 5 m) Uniform periodicity FODO based optics Relatively low quadrupole gradients Modest chromatic corrections required Two pairs of sextupoles in Spreader and Recombiner regions Challenges/Cons. Large total length of the Arcs RLA I: =772 m RLA II: =1544 m Multiple (3) injection double chicanes Spreader/Recombiner switchyards required at both linac ends Multiple ‘crossings’ of the droplet Arcs (4 crossings in each RLA)

Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility Alex Bogacz NuFact’08, Valencia, Spain, July 4, 2008 Non-Scaling FFAG Ring ( GeV) Benefits/Pros. Large chromatic acceptance (2 × inj. energy) Large number of passes through RF cavities At least 8, could be made as high as 15 RF systems expensive (cost benefit - RLA limited to 4-5 passes due to switchyard complexity) Acceleration using high-gradient SRF Compact ring: 463 m circumference Challenges/Cons. Injection and extraction kickers Relatively strong fields (a few kGauss) Large aperture (11 cm wide if open mid-plane, >20 cm wide if a ‘closed box’, what is are the limits ??) Moderately fast (10 -6 sec.) More efficient designs introduce stronger longitudinal distortions No synchrotron oscillations No correction of energy loss down the bunch train Small, probably tolerable effect Correctable with slight frequency offset No correction of time of flight dependence on transverse amplitude

Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility Alex Bogacz NuFact’08, Valencia, Spain, July 4, 2008 Summary Acceleration Goals – Large acceptance acceleration to 25 GeV + beam ‘shaping’ Various fixed field accelerators at different stages IDS Acceleration scenario optimized to take maximum advantage of appropriate acceleration scheme at a given stage Laying out engineering design foundation Carry out end-to-end tracking study  Machine Acceptance

Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility Alex Bogacz NuFact’08, Valencia, Spain, July 4, 2008 What if FFAG Challenges too big/costly? - Plan B 1.2 GeV/pass 7.2 GeV 1.8 GeV 244 MeV 300 m 160 m 4 GeV/pass 528 m 25.2 GeV 244 MeV 0.6 GeV/pass 3.6 GeV 0.9 GeV 146 m 79 m 2 GeV/pass 264 m 12.6 GeV ×2×2