-Capture, Energy Rotation, Cooling and High-pressure Cavities

David Neuffer

Fermilab

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0utlineMotivation Study 2AP Neutrino factory Muon Collider, High-frequency Buncher and RotationStudy 2Ap scenario, obtains up to ~0.2 /pIntegrate cooling into phase-energy rotationGas-Cavity VariationsCooling in bunching and phase rotationHigher gradient, lower frequency ???Shorter system, fewer bunches Optimization .PolarizationUse high gradient rf near target to improve polarization

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Advantages of high-pressure cavities high gradient rfIn magnetic fields B=1.75T, or more With beamChange cavity frf by Can Integrate cooling with captureCapture and phase-energy rotation + coolingCan get high-gradient at low frequencies (30, 50, 100 MHz ???)Beam manipulationsPolarization

Research can be funded

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Study2A Dec. 2003June2004 Drift 110.7mBunch -51mV = 3(z/LB) + 3 (z/LB)2 MV/m ( 2/3) (85MV total)(1/) =0.0079-E Rotate 52m (416MV total)12 MV/m ( 2/3)P1=280 , P2=154 V = 18.032Match and cool (100m)V = 15 MV/m ( 2/3)P0 =214 MeV/c 0.75 m cells, 0.02m LiH

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Study2AP June 2004 scenarioDrift 110.7mBunch -51mV(1/) =0.007912 rf freq., 110MV330 MHz 230MHz-E Rotate 54m (416MV total)15 rf freq. 230 202 MHzP1=280 , P2=154 NV = 18.032Match and cool (80m)0.75 m cells, 0.02m LiHRealistic fields, componentsFields from coilsBe windows included

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Simplest ModificationAdd gas + higher gradient to obtain cooling within rotator~300MeV energy loss in cooling regionRotator is 51m;Need ~6MeV/m H2 Energy loss 9MeV/m if cavities occupy 2/3 ~30% Liquid H2 densityAlternating Solenoid lattice in rotator21MV/m rf

Try shorter system

Cool here

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Short bunch train optionDrift (20m), Bunch20m (100 MV) Vrf = 0 to 15 MV/m ( 2/3)P1 at 205.037, P2=130.94N = 5.0Rotate 20m (200MV)N = 5.05Vrf = 15 MV/m ( 2/3)Palmer Cooler up to 100m Match into ring coolerICOOL results0.12 /p within 0.3 cmCould match into ring cooler (C~40m) (~20m train)60m40m95m

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FFAG-influenced variation 100MHz100 MHz example90m drift; 60m buncher, 40m rf rotation

Capture centered at 250 MeV

Higher energy capture means shorter bunch train

Beam at 250MeV 200MeV accepted into 100 MHz buncher

Bunch widths < 100 MeV

Uses ~ 400MV of rf

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Lattice Variations (50Mhz example)Example I (250 MeV)Uses ~90m drift + 100m 10050 MHz rf (

Polarization for +-- CollidersStart with short proton bunch on target < ~1nsBefore + decay, use low-frequency rf to make beam more monochromatic~50MV in ~5m?Drift to decay (~10m?)Higher energy s pol. +Lower energy s pol. Phase-Energy rotation~10mRebunch at ~2 frequency+s in one bunch-s in other bunch

++--

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SummaryHigh-frequency Buncher and E Rotator (-Factory) improved (?) with high-pressure cavitiesShorter systemsLower Frequency (fewer bunches).+-- Colliders Polarization

To do:Optimizations, Best Scenario, cost/performance

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Current Status (New Scientist)(or +-- Collider)

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DoE/NSF today

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