MICE Beamline Optics Design

paul drumm, mutac jan 2003 1

MICE Beamline Optics Design

Kevin Tilley, RAL, 12th June

• MICE Needs

• Generic Solution

• Pion Injection & Decay Section (a) Inputs (b) Solution

• Muon Transport (a) Inputs (b) Solution

• εn Generation/Matching (a) Inputs (b) Solution

• Current & projected status.


2

MICE Muon Beam - Generic Needs

• MICE Generic Needs:-

– High flux muon beam (>600 muons thru-going MICE lattice / msec )

– High purity muon beam ( < 0.1 % contamination)

– Muon momenta ~ 140 - 240 MeV/c

– Muon emittances ~ 1 π mm rad - 10 π mm rad.

– Beam matched into MICE Lattice

– Also:-

– Desirable muon momentum spread of at least dp/p=+/-10% full width.


3

MICE Beamline Design - General Solution

• General Solution:-

– Many similar requirements to Condensed Matter Pion-Muon Decay beamlines:-• PSI uE4• TRIUMF muon beamlines• RAL-RIKEN muon beamline

– Thus we adopted to design a pion-muon decay beamline.

– For us, demark into 4 functions: -

• pion injection

• decay

• muon transport

• εn generation / matching


4



5


• Codes: TRANSPORT / DECAY TURTLE : – Why?

• Since both codes had extensive history / support.• Both codes had been used to design all aforementioned pion-muon decay channels:-

– PSI uE4– TRIUMF muon beamlines– RAL-RIKEN muon beamline

– How used?• Pion injection & decay channel:-

– Straightforward use of 2nd order TRANSPORT• Muon transport

– Muon source comes from DECAY TURTLE– Optical design using TRANSPORT to both:-

» fit to desired conditions» sometime fit and find 'difference' for driving TTL to desired conditions.

– Always iteration between TTL / TPT until rqd conditions met (as seen in Turtle)• Pb. diffuser

– Thickness set from scattering seen in DECAY TURTLE (uses REVMOC)• Beamline materials (except Pb)

– Modelling consistently in both codes with same Δp as G4Beamline but free 2


6

Pion Injection & Decay Channel - Inputs/Constraints

• Geometry:-

• Target - Beamline Angle of ~20° chosen to allow high energy pion capture.

• Hence Target to Q1 centre shortest is 3.0m due to proximity to Synchrotron

• Hole Drilled ! (April 2004)

• z-position :- to avoid old HEP tunnel ?

• - to avoid Synchrotron electrical junction box

• Hence length of pion injection fixed, at Target - B1 centre ~ 7.98m

• B1 – Decay Sol distance set since Decay Sol to fit wall-hole geometry (hole ≈ 650mm)


7

Pion Injection & Decay Channel - Solution

• Flux:-

• Maximise # pions into decay section -> maximises useful muon flux @ MICE

– normally length (fixed)

– magnets (limited)

– optics

• Maximise accumulation of muons in decay section

– highest decay solenoid field, consistent with controllable beam profile.

• Purity :-

• Chose always ~ highest pion momenta possible - to allow

selection of 'backward' going muons for

higher purity & higher fluxes.

(Risk is assumption of accurate modelling of pion spectrum from target,

but Target test in October'06 may tell us answer?):-

• Inclusion of C2H4 'proton absorber' (ranges out protons < ~ 500MeV/c) -> greatly aids purity

Local peak muon flux at backward momentum, & possessing small

Local peak muon flux at backward momentum, & possessing small


8

Almost all emittance, momenta cases use same pion optic above. (1 envisaged exception)

C2H4 'Proton absorber'




Q1'

Q2'

Q3'Q1 Q2 Q3 B1 Solenoid

Vertical Half-width

(cm)

HorizontalHalf-width

(cm)

25

0

25

16mz

Q1'

Q2'

Q3'

Q1'

Q2'

Q3'

Q1'

Q2'

Q3'Q1 Q2 Q3 B1 Solenoid

Vertical Half-width

(cm)


(cm)

25

0

25

16mz



9


146086 46836146086

• Compares fairly well with RAL-RIKEN:- Injection efficiency ~ 0.82 RIKEN

Efficiency of accumulating muons ~ 0.66 RIKEN

(even though we have longer distance to Q1, longer quads, smaller aperture quads,

and a longer pion injection than the RAL-RIKEN beamline. Also solenoid is shorter!)

• The pion injection & decay channel geometry & optic have remained unchanged since ~ CM8 in April 2004 :- under many different emittance and momentum designs. Sole changes have been scaling the fields of Q1-Q3, B1 & Decay Solenoid. May require small change for 10π,240MeV/c case

58.8 %58.8 %58.8 %58.8 %

• Comparison with RAL-RIKEN pion injection & decay channel:-


10

• To provide beam for emittance generation & matching.

• Sufficient to deliver wide range of matched emittances into MICE.

• To include PID detectors & TOF0 – TOF1 Min Sepn 6.11m (deemed sufficient at CM9 for 6π / 200MeV/c case).

• Presence of upstream iron detector shield -> Q9 downstream mirror plate – Start / End Coil 1.1 distance no closer than 550.8mm.

• Not required to be achromatic but dispersion should be "small" ! (VC Jan 12 04!)

Muon Transport, εn generation & Matching: - Inputs/Constraints


11

• Flux:-

• Aimed at keeping B2 - Q4 distance as small as possible to capture maximum muon solid angle

• Aimed at keeping beamline length short to minimise beamsize growth due to PID detectors.

• Aimed at positioning PID detectors near beam foci to minimise emittance blowup.

(both of the above competitive with keeping a minimum TOF0-TOF1 separation.)

• Purity:-

• Selection of backward going muons.

• Matching:-

• Scheme described in more detail in later slide, but:-

• Focus beam with a beamsize a function of desired emittance

• Triplet lattice, in order to facilitate:- ie. focus and same beamsize both planes at MICE

• Perform emittance generation immediately before MICE.

Possible beam transport correction schemes.

Muon Transport, εn generation & Matching: - Solution


12

Muon Transport - Solution

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)


(cm)

25

0

25

16mz

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)


(cm)

25

0

25

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)


(cm)

25

0

25

16mz

q4

q5

q6

q7

q8

q9

-25

-20

-15

-10

-5

0

5

10

15

20

25

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Diffuser

TOF0

Ckov1

TOF1

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)


(cm)

25

0

25

16mz

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)


(cm)

25

0

25

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)


(cm)

25

0

25

16mz

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)


(cm)

25

0

25

16mz

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)


(cm)

25

0

25

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)


(cm)

25

0

25

16mz

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)


(cm)

25

0

25

16mz

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)


(cm)

25

0

25

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)


(cm)

25

0

25

16mz

q4

q5

q6

q7

q8

q9

-25

-20

-15

-10

-5

0

5

10

15

20

25

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Diffuser

TOF0

Ckov1

TOF1

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)


(cm)

25

0

25

16mz

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)


(cm)

25

0

25

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)


(cm)

25

0

25

16mz

q4

q5

q6

q7

q8

q9

-25

-20

-15

-10

-5

0

5

10

15

20

25

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Diffuser

TOF0

Ckov1

TOF1

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)


(cm)

25

0

25

16mz

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)


(cm)

25

0

25

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)


(cm)

25

0

25

16mz

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)


(cm)

25

0

25

16mz

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)


(cm)

25

0

25

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)


(cm)

25

0

25

16mz

example for 7.1π mm rad case given above


13

εn generation & matching into MICE - Solution

• The scheme. Place Pb Diffuser at MICE End Coil 1.1

-> (p/moc)R.R'= εn, rms R/R'=2p/qB= βmatch α=0= αmatch


14

-> (p/moc)R.R' ~ εn, rms ~7.1π mm rad R/R'=2p/q ~ βmatch α ~ 0= αmatch

Example achieves ~ matched 7.1π mm rad

Example from 6π mm rad, 200MeV/c attempt

εn generation & matching into MICE - Solution

Xrms ~ 3.55 cm , x’rms = 107 mrad , rxx'=0.04 yrms ~ 3.61 cm , y’rms = 102 mrad ryy'=0.13


15

Current & projected status.

• Designs in TRANSPORT/TURTLE

p

1 6 10

240 Scale pion 200/1pi optic.

New muon optic perfect focus beam

at 1.3cm

Just scale 200/6pi case

Slight change to 200/10pi pion optic.

Just scale 200/10pi muon optic



at 1.3cm

~ Done (7.1

Done



at 1.6cm

Scale pion 200/6pi optic.

New muon optic

Scale 200/10pi optic. New muon

optic (diffuser size though?)

Red = dubious (without collimation)

Green = projected to be possible

Documents

MICE Beamline Optics Design