Mu2e Production/Capture...

Mu2e Production/CaptureSolenoid

R. Coleman Mu2e/COMET Joint Workshop

LBNL 23-24 Jan 2009

ProductionSolenoid

TransportSolenoid

DetectorSolenoid

ProtonTarget

TargetShielding

Muon BeamCollimators

Tracker

Calorimeter

Pions ElectronsMuons

Muon Stopping Target

Mu2e Muon Beamline- follows MECO design

Muons are collected, transported, and detected in solenoidal magnets

L= 5.2 m with B= 2.5 to 5 TTarget 16cm r=3mm W,Au,PtCu bore, r= 30cmCryostat r~ 1.2m76 metric ton water cooled shield- 16 kW

0 m

1 m

COMET

Mu2e

Summary of MECO simulations• Stopped muon/ proton = 0.0022-.0025• “Mirror” is 30% of muon yield• PS bore r= 20-25-30 cm -> 96-99.5-100%• TS bore 20-30 cm dia. -> 56-100%• Insensitive to small variation in target z• Field max 5-4.7-4.5T -> 100-98-94%• Water cooled target vs radiative <5%• Proton beam angle 170 +/- 5 deg. -> few %• Target radius 3-6-9mm -> 100 -78- 50%• Target L 12-20 cm ~ same

G4beamline model

• G4beamline program from Muons,Inc-TomRoberts

• Mu2e G4beamline model by Mike Martens• Details, pictures, results, comparisons to

MECO

Some G4beamline results

stopped muon/ proton = 0.60 x 0.0045 =.0027

MECO = 0.0022-.0025

Tracking only pions, muons, protons for u/preaching stopping target gives ~94% of yieldthat tracking all particles gives.

Another interesting number charged flux:(80% e-) = 0.017

Pe~3.5 MeV, Pmu~40 MeV

e-

µ -

Momentum (MeV/c)

e- /µ - flux at stopping target

Time distribution at stopping target

Time (ns)

e-

µ -

Muon Flux Exiting PS and Entering Detector

P (MeV/c)

106 protons incident

Condition Relativeu/p

ChargedFlux

Standard(ztgt=1.36 -> -1.0 m) 0.59 0.68Standard(ztgt=1.36 -> 0.0 m) 0.85 0.99Standard (ztgt= 1.36 -> 2.0m) ~1 ~1Standard (ztgt= 1.36 -> 3.0m) 0.82 0.88

Flat PS field 2.5T 0.53 0.85*Graded PS 4T to 2.5 T 0.85 0.96

PS&TS fields scaled down by0.80

0.46 0.82

Bz vs z

0

1

2

3

4

5

6

-3000 -2000 -1000 0 1000 2000 3000 4000 5000 6000

z (mm)

Bz

(T)

Standard Target Position

Some variations using G4beamline

mu/p Yield vs target postion in PS solenoid

0

0.2

0.4

0.6

0.8

1

1.2

-1 0 1 2 3 4

ztgt (m)

Rela

tive

muo

n yi

eld

G4beamline

MECO early memo

Target z positionStudy

QGSP in G4beamline reproduces GHEISHA abovePion Multiplicity ~right ~ 2

MECO-009April 1997

Armutliiski et al 10 GeV pTa….30% statistical errors - 1mm thick plates

MECO-122 April 2004 Angular distribution of pions in Models vs Data - Ekin = 20-60 MeV

MECO ran simulations with Fluka or modified QGSP

Bin-by-bin correction to match models and 1mm Ta data in Ekin pion = 20-60 Mev ( p=77-143 MeV)

Simulations give ~75% signal from first proton interaction

G4beamline: Cannot do modified QGSP without GEANT4 modsCannot do bin by bin using pion kinematics- NA

G4beamline/QGSP vs data (Armutliiski et al )Ekin pion = 20-40 MeV

0

10

20

30

40

50

60

70

80

90

-1 -0.5 0 0.5 1

cos angle

Even

ts data

QGSP

G4beamline/QGSP vs data (Armutliiski et al )Ekin pion =40-60 MeV

0

10

20

30

40

50

60

70

-1 -0.5 0 0.5 1

cos angle

Even

ts data

QGSP

Generate 75 MeV pion vs angle - Simplifiedsystem - point source no target material

75 MeV pi to mu at stopping target vs angle

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

cosine polar angle

pio

n a

ccep

tan

ce

Series1

Repeat plot for muons reaching last collimator

0

0.1

0.2

0.3

0.4

0.5

0.6

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

cosine polar angle

pio

n a

ccep

tan

ce

Series2

Muons Passing Coll 3 Muons Incident at Coll 3

-1 Cos Θ 1

Recent HARP data vs MECO fit to earlier data Armutliiski et ald2σ/dp dΘ vs p For different angular bins

P = 100 to 800 MeV

.35-.55 radians .55-.75

1.15-1.35 1.35-1.55

1.95-2.15

0.35-0.55 radians

0

0.5

1

1.5

2

2.5

3

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

pion momentum (GeV)

.35-.55 radians

.55-.75 radians

0

0.5

1

1.5

2

2.5

3

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

pion momentum (GeV)

.55-.75

.75-.95 radians

0

0.5

1

1.5

2

2.5

3

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

momentum (GeV)

.75-.95

.95 to 1.15 radians

0

0.5

1

1.5

2

2.5

3

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

pion momentum (GeV)

1.05-1.15

1.15 to 1.35 radians

0

0.5

1

1.5

2

2.5

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

pion momentum (GeV)

1.15-1.35


0

0.5

1

1.5

2

2.5

3

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

pion momentum (GeV)

1.35-1.55


0

0.5

1

1.5

2

2.5

3

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

pion momentum (GeV)

1.55-1.751.75-1.95

1.95-2.15 radians

0

0.5

1

1.5

2

2.5

3

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

pion momentum (GeV)

1.95-2.15


0

0.5

1

1.5

2

2.5

3

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

pion momentum (GeV)

1.75-1.95

Summary• General agreement with MECO• Need a better understanding of yield vs

complexity/spending/risk of capturing forwardpion via “mirror”– Fit HARP data and input via GEANT4– Map acceptance - pi/mu capture (P, angles)– Longer term move to GEANT4 simulations– Start MARS energy deposition studies

• And of course, very interested in understandingand comparing with COMET design!

Extra slides

Muon Muon Production PointsProduction Pointsµπµν++→+

µπµν−−→+

µ+ are mostly producedat wall surfaces by decay of π+ stopped near surface

µ− are mostly producedby decay of in-flight π−

standard graded field and a flat 2.5 T field

ALL (pi+,pi-,mu-,mu+,e+,e-,p) for 1E6 protons on targetStandard Graded 4T Flat 2.5T

Coll 1 In 135.1 K 119.6 K 82.4Coll 1 Out 82.2 74.2 58.7

Coll 3 In 61.3 59.2 50.2Coll 3 Out 24.9 23.4 20.0

Coll 5 In 23.9 23.2 19.5Coll 5 Out 17.3 16.7 14.9

p for 1E6 protons on target

Standard Graded 4T Flat 2.5T

Coll 1 In 9682 7470 4167Coll 1 Out 3990

Coll 3 In 983Coll 3 Out 2

Coll 5 In 0Coll 5 Out 2 0

pi+ for 1E6 protons on target


Coll 1 In 16.5 13.3KColl 1 Out 5842

Coll 3 In 655 476Coll 3 Out 0


pi- for 1E6 protons on target


Coll 1 In 15.1 12.4 KColl 1 Out 5407



mu- for 1E6 protons on target


Coll 1 In 33.9 K 29.3KColl 1 Out 21.0

Coll 3 In 17.2Coll 3 Out 9.24 K

Coll 5 In 9086Coll 5 Out 2879 2445 1553

mu+ for 1E6 protons on target


Coll 1 In 37.5 KColl 1 Out 23.2

Coll 3 In 19.2 KColl 3 Out 291


Production Solenoid Field SpecsProduction Solenoid Field Specs

Axial field on axis:within 5% of expected valueand dBs/ds<−0.02 T for R<30 cm.

L= 4mClear bore R=30 cm,radiation/heat shield R=30cm to R=70 cm 5 cm thick strongback cylinder supportCryo inner radius=75cm.

T

T/m

m

m

MECO-doc-167-v120015T-2T PSSimilar L

Stopping TgtP dependence

And 0.90 for PS4.5T to 2T

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