μ-Capture, Energy Rotation, Cooling and High-pressure Cavities
David Neuffer
Fermilab
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0utline Motivation
Study 2AP Neutrino factory … Muon Collider, …
“High-frequency” Buncher and Rotation Study 2Ap scenario, obtains up to ~0.2 /p Integrate cooling into phase-energy rotation
Gas-Cavity Variations Cooling in bunching and phase rotation Higher gradient, lower frequency ??? Shorter system, fewer bunches Optimization ….
Polarization Use high gradient rf near target to improve
polarization
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Advantages of high-pressure cavities
high gradient rf In magnetic fields B=1.75T,
or more … With beam
Change cavity frf by Can Integrate cooling
with capture Capture and phase-energy
rotation + cooling Can get high-gradient at
low frequencies (30, 50, 100 MHz ???)
Beam manipulations Polarization Research can be funded…
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Study2A Dec. 2003June2004 Drift –110.7m Bunch -51m
V’ = 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 = 18.032
Match 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 scenario Drift –110.7m Bunch -51m
V(1/) =0.0079 12 rf freq., 110MV 330 MHz 230MHz
-E Rotate – 54m – (416MV total) 15 rf freq. 230 202 MHz P1=280 , P2=154 NV = 18.032
Match and cool (80m) 0.75 m cells, 0.02m LiH
“Realistic” fields, components Fields from coils Be windows included
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Simplest Modification Add gas + higher gradient to
obtain cooling within rotator
~300MeV energy loss in cooling region
Rotator is 51m; Need ~6MeV/m H2 Energy loss 9MeV/m if cavities occupy 2/3 ~30% Liquid H2 density
Alternating Solenoid lattice in rotator
21MV/m rf
Try shorter system …
Cool here
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Short bunch train option Drift (20m), Bunch–20m (100 MV)
Vrf = 0 to 15 MV/m ( 2/3) P1 at 205.037, P2=130.94 N = 5.0
Rotate – 20m (200MV) N = 5.05 Vrf = 15 MV/m ( 2/3)
Palmer Cooler up to 100m Match into ring cooler
ICOOL results 0.12 /p within 0.3 cm
Could match into ring cooler (C~40m) (~20m train)
Cool (to 100m)
Rotate(20m)Bunch
(20m)
Drift (20m)
60m
40m
95m
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FFAG-influenced variation – 100MHz 100 MHz example
90m 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 (<4MV/m) ~300MV total
Captures 250200 MeV ’s into 250 MeV bunches with ±80 MeV widths
Example II (125 MeV) Uses ~60m drift + 90m
10050 MHz rf (<3MV/m) ~180MV total
Captures 125100 MeV ’s into 125 MeV bunches with ±40 MeV widths
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Polarization for μ+-μ- Colliders Start with short proton
bunch on target < ~1ns Before π⇒μ+ν decay, use
low-frequency rf to make beam more monochromatic ~50MV in ~5m?
Drift to decay (~10m?) Higher energy μ’s pol. + Lower energy μ’s pol. –
¼ Phase-Energy rotation ~10m
Rebunch at ~2× frequency +’s in one bunch -’s in other bunch
+
+
-
-
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Summary High-frequency Buncher and E Rotator (ν-
Factory) improved (?) with high-pressure cavities Shorter systems Lower Frequency (fewer bunches).
μ+-μ- Colliders …
Polarization …
To do: Optimizations, Best Scenario, cost/performance …
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Current Status (New Scientist)
(or μ+-μ- Collider)
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DoE/NSF today …
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