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Quad Channel Cooling Update. David Neuffer Fermilab. Quad Channel. Previously developed by Makino, Johnstone, Errede, Berz In this study, evaluated for Study 2A compatible case using ICOOL. FODO Study2A. Use 1.5m long cell – FODO lattice 60º to 90º/cell at P = 215MeV/c
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Quad Channel CoolingUpdate David Neuffer Fermilab
Quad Channel • Previously developed by Makino, Johnstone, Errede, Berz • In this study, evaluated for Study 2A compatible case using ICOOL
FODO Study2A • Use 1.5m long cell – FODO lattice • 60º to 90º/cell at P = 215MeV/c • max = 2.6m;min=0.9 to 0.6m • B’ = 4 to 6 T/m
Simulation Results • Cooling in FODO cells • 2 1cm LiH slabs • Gas H2
Advantages of Quad Channel • No large magnetic fields along the axis • Reduced breakdown problems • Magnets much cheaper • No Amplitude–Momentum correlation in Cooling • No beam angular momentum effects • No preferred absorber location (gas cavity OK) Disadvantages of FODO Quad channel • No low * region • Relatively weak focusing • Elliptical beam profiles
Use in Study2A? • Replace Cooler with FODO cooler • Solenoid to lattice “match” with 4 quads, ~2m (not well-optimized) With H2 absorbers, similar to Study 2A LiH performance ECALC9 initially used, but ECALC9 valid only for symmetric (x=y) solenoidal lattices. With x-y version of Ecalc9, similar to Study2A To Do Better Matching Extend to Buncher/Rotator ??
Evaluate with x-y emittances • Ecalc9xy written • Separately evaluates εx, εy, x, y, etc. • Acceptance is: • Ax + Ay < ref1, ref2 • with H2 absorber • Same as study 2A baseline • Study 2A acceptance same under ecalc9 and ecalc9xy • LiH absorber • Quad channel, match not well optimized Ecalc9xy quad channel Ecalc9 Study2A 5000 initial particles
Extend to buncher/rotator ? • Try placing solenoid to quad match before buncher • Does not work well • Low-energy beam is immediately lost (E<~80 MeV) (P<150MeV/c) • ~1/2 beam lost in first few meters of buncher • Only ~50% of Study 2A • Quad focusing does not work for very broad energy spread of buncher/rotator • Does work for cooler • Matches energy acceptance quads solenoids