Mu2e Production/Capture...
Transcript of 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
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-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
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-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
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10
20
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-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
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10
20
30
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-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
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-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
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0.1
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-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
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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
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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
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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
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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
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0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
pion momentum (GeV)
1.15-1.35
1.35 to 1.55 radians
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pion momentum (GeV)
1.35-1.55
1.55 to 1.75 radians
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pion momentum (GeV)
1.55-1.751.75-1.95
1.95-2.15 radians
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0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
pion momentum (GeV)
1.95-2.15
1.75 to 1.95 radians
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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
Standard Graded 4T Flat 2.5T
Coll 1 In 16.5 13.3KColl 1 Out 5842
Coll 3 In 655 476Coll 3 Out 0
Coll 5 In 0Coll 5 Out 0 0
pi- for 1E6 protons on target
Standard Graded 4T Flat 2.5T
Coll 1 In 15.1 12.4 KColl 1 Out 5407
Coll 3 In 524 481Coll 3 Out 88
Coll 5 In 38 7Coll 5 Out 7
mu- for 1E6 protons on target
Standard Graded 4T Flat 2.5T
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
Standard Graded 4T Flat 2.5T
Coll 1 In 37.5 KColl 1 Out 23.2
Coll 3 In 19.2 KColl 3 Out 291
Coll 5 In 275Coll 5 Out 47 56
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