Front End Studies International Design Study & Muon Collider
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Transcript of Front End Studies International Design Study & Muon Collider
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Front End StudiesFront End StudiesInternational Design Study &International Design Study &
Muon ColliderMuon Collider
David Neuffer
December 2009
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OutlineOutline Front End for the Neutrino Factory/MC
Concepts developed during study 2A
Concern on Vrf’ as function of Bsol ~200MHz, 10+ MV/m B= ~2T Variations
Need baseline design for IDS need baseline for engineering study updated version to match IDS
•~lower fields; medium bunch length
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Plan for IDSPlan for IDS Need one design likely to work for Vrf/B-
field rf studies are likely to be inconclusive B=1.25T; V’ = 10MV/m is very likely to work B= 2T; V’ = 15 MV/m should work with Be
Hold review to endorse a potential design for IDS – likely to be acceptable (Vrf/B-field) April 2010 ?
Use reviewed design as basis for IDS engineering study
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Solutions for possible rf cavity Solutions for possible rf cavity limitationslimitations
Potential strategies: Use lower fields (V’, B)
10MV/m at 1.5T? Use non-B = constant lattices
alternating solenoid Magnetically insulated
cavities Is it really better ??? Alternating solenoid is similar to
magnetically insulated lattice Shielded rf lattices
low B-field throughout rf Use gas-filled rf cavities
same gradient with/without fields but electron effects?
Use Be Cavities should have better B/ V’rf
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Shielded rf cooling channel (C. Shielded rf cooling channel (C. Rogers)Rogers)
Lattice that keeps B small within rf cavities Iron placed around coils B < 0.25T at rf
Problems rf occupancy ~1/3 larger β* (~1m) tranverse acceptance
Still has fair cooling increases μ/p by 1.7
3m
rf cavity
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Baseline IDS candidateBaseline IDS candidate ISS study based on nB = 18 ( 280 MeV/c to 154 MeV/c)
1.75T, 12MV/m Reference -shorter has nB = 10 ( 280 MeV/c to 154
MeV/c) slightly higher fields (2T, 15MV/m)
Looking for candidate variation for IDS developing intermediate case, with a bit weaker fields
10 m ~50 m
FE
Tar
getSolenoid Drift Buncher Rotator Cooler
~32m 36m up to ~100m
m
pπ→μ
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Recent Studies on Lower Fields Recent Studies on Lower Fields Adequate acceptance can be
obtained by reducing magnetic fields and gradients
B -> 1.25T, V’ -> 10 MV/m ?? (10MV/m is 7MV/m real estate
gradient; could use 7MV/m if space is filled.)
Reduced B, V’ are relatively certain to work.
Cost optimum? B=1.5T ?, 12MV/m
0.75T, 14MV/m
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Look at performance if V’Look at performance if V’rfrf is is reducedreduced
Muons per 10 8-GeV protonsCooler/Rotator
10 12 14 15 17 18 MV/m
10 0.35 (0.63)
0.55(0.67)
0.66 0.73
12 0.57(0.72)
0.754
0.77 0.80
14 0.776
0.800.82
0.84
15 0.81 0.850.88
0.84
(0.65cm)
(0.8cm)
Variation is not strong; more rf still means more muons
B=2T (B=1.25T ~5% worse) - B= 1.5T ~5% better
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Front End ReOptimizationFront End ReOptimization Change reference B-field to
1.5T constant B to end of rotator
Redoing nB =“12” example A bit longer than nB = 10 optimize with lower fields
• V’rf < 12 MV/m Will see if we can get “better”
optimum
18.9 m ~60.7 m
FE
Targ etSolenoid Drift Buncher Rotator Cooler
~33m 42m up to ~100m
m
pπ→μ
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High-frequency Buncher and High-frequency Buncher and φφ-E -E RotatorRotator
Drift (π→μ) “Adiabatically” bunch beam first (weak 320 to 232 MHz rf) Φ-E rotate bunches – align bunches to ~equal P
(233MeV/c) 232 to 202 MHz, 12MV/m
Cool beam 201.25MHz
18.9 m ~60.7 m
FE
Targ et Solenoid Drift Buncher Rotator Cooler
~33m 42 m ~80 m
pπ→μ
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Parameters of candidate releaseParameters of candidate release Initial drift from target to buncher is 79.6m
18.9m (adiabatic ~20T to ~1.5T solenoid) 60.7m (1.5T solenoid)
Buncher rf – 33m 320 232 MHz 0 9 MV/m (2/3 occupancy) B=1.5T
Rotator rf -42m 232 202 MHz 12 MV/m (2/3 occupancy) B=1.5T
Cooler (50 to 90m) ASOL lattice, P0 = 232MeV/c, Baseline has 15MV/m, 2 1.1 cm LiH absorbers /cell
0.00
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0.00 50.00 100.00 150.00 200.00 250.00 300.00
0.08
0.00
μ/p
cooling
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progression through systemprogression through system
z =1m 80m
112m 156m 215m
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NF Release CandidateNF Release Candidate Front End a bit longer
than “short” example ~50m shorter than ISS,
however gradients no greater than
ISS baseline slightly better
“performance”
66m bunch window
0.000
0.004
0.008
0.012
0.016
0.020
0 40 80 120 160 200 240 280
Series1
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How Long a Bunch Train for IDS?How Long a Bunch Train for IDS? ISS study alotted space
for 80 bunches (120m long train) 80m or 54 bunches is
probably plenty
-20
40-30
100
~50m
~80m
Study 2A
nB =10
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Bunch train lengthBunch train length Within IDS design could
reduce bunch train to ~80m (52 bunches) very little mu loss
With shorter front end, could reduce that to 50m or less For Collider scenario ~12
best bunches, (18m) contains ~70% of muons
Reserving 80m for bunch trains should be adequate for IDS
20m
Study 2A
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BB00 = = 1.5T, 1.5T, nnBB = 12 RC = 12 RC Muons per 10 8-GeV protons (At< 0.03,
AL<0.02) Cooler/Rotator
10 12 14 15 16 18 MV/m
10 0.35 (0.63)
0.55(0.67)
0.66 0.73
12 0.57(0.72)
0.7540.84
0.770.856
0.88 0.80
14 0.776
0.80 0.84
15 0.81 0.85 0.84
(0.65cm)
(0.8cm)
1.0cm
1.1cm
1.15Black are old nB = 10 example; new version is Green
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Varying Buncher/Rotator VoltageVarying Buncher/Rotator Voltage Vary buncher/rotator gradients from
baseline to explore sensitivity to gradient limits. same baseline cooling channel (16MV/m, 1.15cm LiH)
• 15 MV/m -> 1.1cm Li H
Somewhat less sensitive than previous
Buncher / Rotator
0/0 3/6 4/7 5/8 6/9 7/10 8/11 9/12
μ/8GeVp at 240m (×10)
.136 .508
.686
.753 .797
.800 .831 .857
10/ 13
11/ 14
.821
.839
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rf requirementsrf requirements Buncher
319.63, 305.56, 293.93,285.46, 278.59, 272.05, 265.80, 259.83, 254.13, 248.67, 243.44, 238.42, 233.61 (13 f)
~100MV total
Rotator 230.19, 226.13, 222.59, 219.48, 216.76,
214.37,212.28, 210.46,208.64, 206.90, 205.49,204.25, 203.26, 202.63,202.33 (15 f)
336MV total
Cooler 201.25MHz –up to 75m ~750MV
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Plans etc.Plans etc. Move toward “realistic” configuration
More realistic B-field • B= 1.5T -> coil-based fields
add Be windows smaller number of rf frequencies
Set up design for cost algorithm rf cavity design (pillbox, dielectric) rf power requirements Magnet design
Continuing front end IDS design study• C. Rogers, G. Prior, D. Neuffer, C. Yoshikawa,
K. Yonehara, Y. Alexahin, M. Popovic, Y. Torun, S. Brooks, S. Berg, J. Gallardo …
Fermilab meeting (July) ~Biweekly phone Conference Meeting at RAL
• December 14-18 April at Fermilab (IDS meeting)
dielectric
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IDS - cost issues …IDS - cost issues …
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Study2B June 2004 scenario (ISS)Study2B June 2004 scenario (ISS) Drift –110.7m Bunch -51m
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
Captures both μ+ and μ-
~0.2 μ/(24 GeV p)