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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

100.00

200.00

300.00

400.00

500.00

600.00

700.00

800.00

900.00

1000.00

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)