mice beamline optics design
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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.
paul drumm, mutac jan 2003 2
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.
paul drumm, mutac jan 2003 3
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
paul drumm, mutac jan 2003 5
5
MICE Beamline Design - General Solution
• 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
paul drumm, mutac jan 2003 6
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)
paul drumm, mutac jan 2003 7
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
paul drumm, mutac jan 2003 8
8
Almost all emittance, momenta cases use same pion optic above. (1 envisaged exception)
C2H4 'Proton absorber'
C2H4 'Proton absorber'
C2H4 'Proton absorber'
Pion Injection & Decay Channel - Solution
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)
HorizontalHalf-width
(cm)
25
0
25
16mz
C2H4 'Proton absorber'
paul drumm, mutac jan 2003 9
9
Pion Injection & Decay Channel - Solution
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:-
paul drumm, mutac jan 2003 10
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• 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
paul drumm, mutac jan 2003 11
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
paul drumm, mutac jan 2003 12
12
Muon Transport - Solution
B2
Q4
Q5
Q6
Q7
Q8
Q9
PbPT
B1B2 Q4 Q5 Q6 Q7 Q9Q8
Pb.Disk
Vertical Half-width
(cm)
HorizontalHalf-width
(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)
HorizontalHalf-width
(cm)
25
0
25
B2
Q4
Q5
Q6
Q7
Q8
Q9
PbPT
B1B2 Q4 Q5 Q6 Q7 Q9Q8
Pb.Disk
Vertical Half-width
(cm)
HorizontalHalf-width
(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)
HorizontalHalf-width
(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)
HorizontalHalf-width
(cm)
25
0
25
B2
Q4
Q5
Q6
Q7
Q8
Q9
PbPT
B1B2 Q4 Q5 Q6 Q7 Q9Q8
Pb.Disk
Vertical Half-width
(cm)
HorizontalHalf-width
(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)
HorizontalHalf-width
(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)
HorizontalHalf-width
(cm)
25
0
25
B2
Q4
Q5
Q6
Q7
Q8
Q9
PbPT
B1B2 Q4 Q5 Q6 Q7 Q9Q8
Pb.Disk
Vertical Half-width
(cm)
HorizontalHalf-width
(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)
HorizontalHalf-width
(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)
HorizontalHalf-width
(cm)
25
0
25
B2
Q4
Q5
Q6
Q7
Q8
Q9
PbPT
B1B2 Q4 Q5 Q6 Q7 Q9Q8
Pb.Disk
Vertical Half-width
(cm)
HorizontalHalf-width
(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)
HorizontalHalf-width
(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)
HorizontalHalf-width
(cm)
25
0
25
B2
Q4
Q5
Q6
Q7
Q8
Q9
PbPT
B1B2 Q4 Q5 Q6 Q7 Q9Q8
Pb.Disk
Vertical Half-width
(cm)
HorizontalHalf-width
(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)
HorizontalHalf-width
(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)
HorizontalHalf-width
(cm)
25
0
25
B2
Q4
Q5
Q6
Q7
Q8
Q9
PbPT
B1B2 Q4 Q5 Q6 Q7 Q9Q8
Pb.Disk
Vertical Half-width
(cm)
HorizontalHalf-width
(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)
HorizontalHalf-width
(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)
HorizontalHalf-width
(cm)
25
0
25
B2
Q4
Q5
Q6
Q7
Q8
Q9
PbPT
B1B2 Q4 Q5 Q6 Q7 Q9Q8
Pb.Disk
Vertical Half-width
(cm)
HorizontalHalf-width
(cm)
25
0
25
16mz
example for 7.1π mm rad case given above
paul drumm, mutac jan 2003 13
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
paul drumm, mutac jan 2003 14
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
paul drumm, mutac jan 2003 15
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
200 Scale pion 200/6pi optic.
New muon optic perfect focus beam
at 1.3cm
~ Done (7.1
Done
140 Scale pion 200/1pi optic.
New muon optic perfect focus beam
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
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