High-Frequency “Adiabatic” Buncher

Report
μ-Capture, Energy Rotation, Cooling
and High-pressure Cavities
David Neuffer
Fermilab
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
2
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…
3
Study2A Dec. 2003June2004
 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
4
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
5
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
6
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
40m
 Rotate – 20m (200MV)
 N = 5.05
 Vrf = 15 MV/m ( 2/3)
 Palmer Cooler up to 100m
60m
 Match into ring cooler
 ICOOL results
 0.12 /p within 0.3 cm
 Could match into ring cooler
(C~40m) (~20m train)
95m
BunchRotate
(20m) (20m) Cool (to 100m)
Drift (20m)
7
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
8
Lattice Variations (50Mhz example)
Example I (250 MeV)
 Uses ~90m drift + 100m
10050 MHz rf (<4MV/m)
~300MV total
 Captures 250200 MeV ’s into
250 MeV bunches with ±80 MeV
widths
Example II (125 MeV)
 Uses ~60m drift + 90m 10050
MHz rf (<3MV/m) ~180MV total
 Captures 125100 MeV ’s into
125 MeV bunches with ±40 MeV
widths
9
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
+
-
10
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 …
11
Current Status (New Scientist)
(or μ+-μ- Collider)
12
DoE/NSF today …
13

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