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 …