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Front End Studies-Front End Studies-International Design StudyInternational Design Study

Muon Collider Muon Collider

David Neuffer

January 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

Need baseline design for IDS need baseline for engineering study

•~lower fields; medium bunch length

Other variations

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Official IDS layoutOfficial IDS layout

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Optimization for IDSOptimization for IDS

ISS study based on nB = 18 (280 MeV/c to 154 MeV/c)

Buncher 0 to 12MV/m; Rotator 12.5MV/m, B=1.75T (201.25 MHz)

Long system,

Obtain shorter version has nB = 10 (280 MeV/c to 154 MeV/c) slightly higher fields (2T, 15MV/m) Shorter bunch train

10 m ~50 m

FE

Tar

get

Solenoid Drift Buncher Rotator Cooler

~32m 36m up to ~100m

m

pπ→μ

10 m ~100 m

FE

Targ etSolenoid Drift Buncher Rotator Cooler

~51m 52m up to ~100m

m

pπ→μ

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Possible rf cavity limitationsPossible rf cavity limitations

V’rf may be limited in B-fieldsbaseline has ~2T, ~15MV/m

Potential strategies: Use lower fields (V’, B)

<10MV/m at 1.5T? Use non-B = constant lattices

alternating solenoid Magnetically insulated cavities Shielded rf lattices

Use gas-filled rf cavities 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 Only in cooling section …

Still has fair cooling increases μ/p by 1.7

3m

rf cavity

rf cavity

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Front End ReOptimizationFront End ReOptimization

Change reference B-field to 1.5T constant B to end of rotator

changing to 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

p

π→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

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Some differences Some differences

Used ICOOL to set parameters ACCEL model 10, Phase Model 0 – zero crossing set by tREFP 1

•refp 1 @ 233MeV/c,

•2 at 154MeV/c, 10 λ

Cool at 232 MeV/c ~10% higher momentum absorbers ~10% longer Cools transverse emittance

from 0.017 to 0.006m

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

μ/8 GeV p

0.08

0.00

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Beam Through SystemBeam Through System

z=0 z=80m

z=111mz=156m

z=236m

∆n=10

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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 cases

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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More realistic modelsMore realistic models

For buncher & rotator replace B=1.5T with “realistic” solenoid coils (B ~1.5T) 0.5 m long, 0.25m spacing ~OK for rf feed in between

ICOOL simulation shows no change in performance (<~1%)

Next: rf smaller number of

rffrequencies• 14 ,B 16 R rf freq. OK

• 7,8 20% less Set rf power requirements

Acceptance of Mu+'s Within Atrans<0.030 m-rad & Along<0.15 m (sigma6.0, To=475.5ns, phase=25.8deg)

0

1000

2000

3000

4000

5000

6000

0 20 40 60 80 100 120 140 160 180 200 220

z (m)

Nu

mb

er

of

Mu

+'s

pe

r 1

00

k P

OT

Benchmark

Grp3RF

Grp6RF

Grp3&6RF

Grp6&3RF

Longitudinal Emittance in Study 2A-like Front End (sigma6.0, phase=25.8deg, To=475.5ns)

0.05

0.07

0.09

0.11

0.13

0.15

0.17

0.19

0.21

0.23

0.25

0 20 40 60 80 100 120 140 160 180 200 220

z (m)

Em

itta

nc

e (

m-r

ad

)

a: Tapered Solenoid

b: Drift

c: Buncher

d: Rotator

e: Match & Cool (4m)

f: Cooler (opposing solenoids)

ba c d e f

(a)

(b)

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rf requirementsrf requirements

Buncher – 13 rf frequencies 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 – 15 rf frequencies 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, 56 rf cavities

Cooler 201.25MHz –up to 75m ~750MV

•~15 MV/m, 100 rf cavities

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Buncher rf cavity requirementsBuncher rf cavity requirements

98.085

3.57.5MV/m4 (0.45m)13.11233.61

7MV/m4 (0.45m)12.16238.42

6.5MV/m4(0.45m)11.225243.44

6MV/m4 (0.45m)10.326248.67

2.257MV/m3 (0.45m)9.405254.13

6.5MV/m3 (0.45m)8.484259.83

5.7MV/m3 (0.45m)7.565265.80

5MV/m3 (0.45m)6.664272.05

6.4 MV/m2 (0.45m)5.724278.59

5.5MV/m2 (0.45m)4.803285.46

4 MV/m2 (0.45m) 3.336293.93

5MV/m2 (0.4m) 3.915305.56

4 MV/m1 (0.4m) 1.368319.63

Rf Power

Gradient

cavitiesTotal voltage

RF frequency

0.2

0.60.51.01.25

1.5

1.52

2.252.5

3

MW

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Rf Rotator/ Cooler requirementsRf Rotator/ Cooler requirements

RF Rotator 56 cavities (15 frequencies)

12 MV/m, 0.5m ~2.5MW (peak power) per cavity

Cooling System – 201.25 MHz 100 0.5m cavities (75m cooler), 15MV/m ~5MW /cavity

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Add Windows effectsAdd Windows effects

ISS had windows … 200μ Be – 7MV/m cavities

•(0.12 MeV energy loss) 395 μ Be – 10MV/m cavities

•(0.24 MeV energy loss) 750 μ Be – 12.5MV/m cavities (Rotator)

•(0.45 MeV energy loss)

MICE rf cavities 380 μ Be window design

For IDS ?? Use 200 μ Be for Buncher Use 400 μ Be for Rotator

Could use Be-grid or “open-cell” ?

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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

~60m

~80m

Study 2A

nB =12

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Recent StudiesRecent Studies

From Juan G.’s studies 8GeV 20T beam from H. Kirk Also 8GeV 30T beam

New H. Kirk initial beam 20 T, 8 GeV beam, Hg target from more recent MARS (?)– (subtract 2.9ns to get mean of

0) more π/8GeV p (~10%)

Tried 30T initial beam scaled 20 to 1.5T to 30 to 2.25

to 1.5T ~20 to 25% more than with 20T

Case μ/p @ z=245m

old CY init beam

0.083

new 20T HK beam

0.090

new 30THK (25cm)

0.107

new 30THK (30cm)

0.113

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Plans etc.Plans etc.

Move toward “realistic” configuration add Be windows

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. Berg, J. Gallardo, D. Stratakis …

~Biweekly phone Conference Cost meeting at CERN March April at Fermilab (IDS meeting)

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Quasi-Isochronous Muon CaptureQuasi-Isochronous Muon Capture

Front end with isochronous HCC 2009 SBIR w C. Yoshikawa 0

1ˆ1

122

2

3

2

TT

D

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U Miss reminds me of my university U Miss reminds me of my university days days

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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)