Upload
others
View
1
Download
0
Embed Size (px)
Citation preview
J-PARCでのμ-e転換過程探索実験--- PRISM/Phase-1 ---
Masaharu AokiOsaka U.
東京大学ICEPP, 2007/11/06
内容• イントロダクション
• Lepton Flavor Violationの理論• μ-LFV実験 (SIMDRUM II)
• μ-e転換過程探索実験• MECO, mu2e and PRISM/Phase-1
• PRISM/Phase-1 @ J-PARC
• まとめ
3
• Quark Mixing : Kobayashi-Maskawa Matrix• Neutrino Mixing : Maki-Nakagawa-Sakata Matrix• charged Lepton Mixing : not-yet-observed
• charged Lepton Flavor Violation (c-LFV)• Neutrino-mixing predicts very small amount of c-LFV via
higher order diagram; it is as small as practically impossible to observe in foreseeable future.
• c-LFV = Physics beyond SM
Lepton Flavor Mixing
A. de Gouvea
4
c-LFVと超対称性
Physics of slepton mass matrix
SUSY!
"
m2ee
!m2eµ
!m2e!
!m2µe
m2µµ
!m2µ!
!m2! e
!m2! µ
m2! !
#
$
c-LFV slepton mixing
!
"m2
ee !m2eµ !m2
e!
!m2µe m2
µµ !m2µ!
!m2! e !m2
! µ m2! !
#
$
Golden Trio
e
e
B~
mixing
large top Yukawa coupling
!0
"
!0
"
c-LFVg-2 EDM
Real Imaginary
τ-LFV
slepton mass matrix
Slepton Mixing Mechanism
GUT Yukawa interactionNeutrino Yukawa interaction
Quark mixing matrix Neutrino mixing matrix
@ Plank mass scale
SUSY-GUT SUSY Seesaw Model
(m2
l)ij = m
2
0!ij
(!m2
l)ij != 0
(m2
L)21 "
3m20 + A2
0
8"2h
2
t V!
tdVts lnMGUT
MRS
(m2
L)21 "
3m20 + A2
0
8"2h
2
i U!
i1Ui2 lnMGUT
MRS
PRISM/Phase-1 LoI (2006)
7
Theoretical Predictions
Process CurrentLimit
SUSY-GUTlevel Future
µ N → e N 10-13 10-16 10-16,10-18
µ → e γ 10-11 10-14 10-13
τ → µ γ 10-6 10-9 10-8
PRSM/PRIME
MEG
Courtesy Hisano
PRISM/PRIME
MEG
SUSY+Seesaw, MSW Large Angle
SUSY-GUT
Phase-1 Phase-1
LHC and c-LFV• if LHC finds SUSY particle
• Physics of slepton mass matrix will be strengthened.
• Further exploration of SUSY structure (SUSY-GUT, SUSY-Seesaw) will become more important.
• if LHC does not findSUSY particle• high-intensity exp.
comes forefront.
L. Calibbi, A. Faccia, A. Masiero, S.K. Vempati, PRD74(2006)116002
μ-LFVμ→eγμ→eeeμN→eN
μ→eγ, μ→eee, μN→eN
L =mµ
!2µR!µ!eLFµ!
+1
!2F
(µL"µeL)(eL"µeL)
+1
!2F
(µL"µeL)(qL"µqL)
c-LFVの一般的なラグランジアン(A. de Gouvea, talk at Nufact’06)
μ→eγ μ→eee μN→eN
tree ×α ×α
1-loop tree ---
1-loop --- tree
photonic
non-photonic
11
• Muonic Atom (1S state)
• MC:MDO = 1:1000(H), 3:2(Al), 13:1(Cu)• τ(μ-;Al) = 0.88 μs; τ(free-μ-) = 2.2 μs
• μ-e Conversion
nucleiµ−Muon Decay in Orbit (MDO)
Coherent Process
μ-e Conversion
Muon Capture(MC)
BR[µ! + (A,Z)! e! + (A,Z)] " ![µ! + (A,Z)! e! + (A,Z)]![µ! + (A,Z)! !µ + (A,Z # 1)]
Physics of μ-e Conversion• SUSY-GUT, SUSY-seesaw (Gauge Mediated process)
• BR = 10-15 = BR(μ→eγ) × O(α)• τ→lγ
• SUSY-seesaw (Higgs Mediated process)• BR = 10-12~10-15
• τ→lη
• Doubly Charged Higgs Boson (LRS etc.)• Logarithmic enhancement in a loop diagram for μ-
N → e-N, not for μ→e γ• M. Raidal and A. Santamaria, PLB 421 (1998) 250
• SUSY with R-parity Violation• Leptquarks• Heavy Z’• Compositeness• Multi-Higgs Models
N N
13
Principal of Experiment
• Signal : μ- +(A,Z) → e- +(A,Z)• A single mono-energetic electron
• 100 MeV• Delayed:~1μS
• No accidental backgrounds• Physics backgrounds
• Muon Decay in Orbit (MDO)• ΔEe=350 keV (BR:10-16)
• Beam Pion Capture• π-+(A,Z) → (A,Z-1)* → γ+(A,Z-1)
γ → e+ e-• Prompt timing
SINDRUM II
PSI/πE5
14
SINDRUM II
• Need more muons:• 1011 μ-/s• J-PARC/MR + Solenoid π cap.
• Beam-induced prompt backgrouds:• Pulsed beam• Long Muon Beam Line
• Detector rate might be too high:• Curved Solenoid Detector.BR < 7 × 10-13
MECO, PRISM and Phase-1
16
MECO BNL/AGSStraw Tracker
Crystal Calorimeter Muon Stopping
Target
Muon Beam Stop
Superconducting Production Solenoid
(5.0 T – 2.5 T)
Superconducting Detector Solenoid
(2.0 T – 1.0 T)
Superconducting Transport Solenoid
(2.5 T – 2.1 T)
Collimators• BR(µ-+Al→e-+Al)<10-16 • Beam Pion Background : Pulsed Beam• 5x1011µ-/spill, 1.1MHz pulse• 8GeV proton beam at AGS • high field capture solenoid of 4T
16
MECO BNL/AGSStraw Tracker
Crystal Calorimeter Muon Stopping
Target
Muon Beam Stop
Superconducting Production Solenoid
(5.0 T – 2.5 T)
Superconducting Detector Solenoid
(2.0 T – 1.0 T)
Superconducting Transport Solenoid
(2.5 T – 2.1 T)
Collimators• BR(µ-+Al→e-+Al)<10-16 • Beam Pion Background : Pulsed Beam• 5x1011µ-/spill, 1.1MHz pulse• 8GeV proton beam at AGS • high field capture solenoid of 4T
Cancelled
17
Staging StrategyOn the evening before the MECO cancellation
5 m
PRISMPhase Rotated Intense Slow Moun source
PRIMEPRISM Muon to Electron conversion experiment
Pion DecayMuon Transport
FFAGPhase-Rotator
Muon-Stopping Target
Proton Beam
PRIMEDetector
Pion Capture
!""# !""$ !""% !""& !"'" !"'' !"'! !"'( !"') !"'* !"'# !"'$ !"'%
+,-. -/01234526/0 740 809:;161
<7=>+ ?@A@:/BC@02 -/01234526/0 740
MECO:BR<10-16 PRISM:BR<10-18
17
Staging StrategyOn the evening before the MECO cancellation
5 m
PRISMPhase Rotated Intense Slow Moun source
PRIMEPRISM Muon to Electron conversion experiment
Pion DecayMuon Transport
FFAGPhase-Rotator
Muon-Stopping Target
Proton Beam
PRIMEDetector
Pion Capture
!""# !""$ !""% !""& !"'" !"'' !"'! !"'( !"') !"'* !"'# !"'$ !"'%
+,-. -/01234526/0 740 809:;161
<7=>+ ?@A@:/BC@02 -/01234526/0 740
MECO:BR<10-16 PRISM:BR<10-18
After the MECO Cancellation• mu2e(FNAL + xMECO)
• Revive of MECO• After the shutdown of Tevatron• Parasite on SNuMI-2
• 2012 ~• Renovate a Debuncher ring for
beam bunching
22 batches = 1. 467s MI cycle
Booster Batches
Accumulator
Recycler
Debuncher
4.6×1012 p/batch
4×4.6×1012 p/1467ms = 12.5 ×1012 p/sec
56 ×1012 p/sec
0.1s 1.367s
NEUTRINO PROGRAM MUONS
(NuMI +Muons)
(NuMI)
(Muons)
(Alternative: 24 batches=1.6s MI cycle→ 11.5 ×1012 p/s)
AP4 Line
AP5 LineA-D Line
Staging of PRISM
StoppingTarget
ProductionTarget
Phase-1:BR<10-16
5 m
PRISMPhase Rotated Intense Slow Moun source
PRIMEPRISM Muon to Electron conversion experiment
Pion DecayMuon Transport
FFAGPhase-Rotator
Muon-Stopping Target
Proton Beam
PRIMEDetector
Pion Capture
Full PRISM:BR<10-18
!""# !""$ !""% !""& !"'" !"'' !"'! !"'( !"') !"'* !"'# !"'$ !"'%
+,-./0' 123 456.789:7;56 196 <6-=>.;.
+1?@A 3/B/=5CD/67 456.789:7;56 196
~10 years
Why Staging, why 10-18
• Staging• Early Realization, Discovery• Understand the phenomena in a
real-world step by step; we may see something new in every step of factor 10 improvements
• Why 10-18, why full-PRISM• Covering almost entire parameter
space• Study of interaction types
• τμ-Al = 880 ns, τμ-Pb = 82 ns
R. Kitano, M. Koike, Y. Okada PRD 66(2002) 096002
Phase-1
PRISM
L. Calibbi, A. Faccia, A. Masiero and S.K. Vempati PRD 74(2006) 116002
Phase-1
Phase-1 Overview
StoppingTarget
ProductionTarget
• Large μ yields
• J-PARC/MRonly 60 kW out of 450kW
• π-capture SC-solenoid• 1011 μ/s (PSI:108 μ/s)
• Pulsed Proton Beam• π-b.g. suppression
• Curved-solenoid detector• Lower detector rate
• Upgradability to PRISM• add Phase-Rotator-Ring
Pulsed Proton Beam
パルス陽子ビーム• バックグランド
• π-+(A,Z) → (A,Z-1)* → γ+(A,Z-1),γ → e+ e- :一次陽子ビームに同期• μ- decay-in-flight, e- scattering, neutron streaming
• 信号• μ- +(A,Z) → e- +(A,Z) : 遅延 (~1μs)
Nbg = NP×Rext×Yπ/P×Aπ×Pγ×ANP : total # of protons (~1021)Rext : Extinction Ratio (10-9)Yπ/P : π yield per proton (0.015)Aπ : π acceptance (1.5×10-6)Pγ : Probability of γ from π (3.5×10-5)A : detector acceptance (0.18)
BR=10-16, Nbg < 0.12⇔ Extinction < 10-9
Extinction: < 10-9Power: 60 kW (4×1013 pps@8 GeV)
0.7 !s
J-PARC• LINAC
• 0.4 GeV• 4π mm.mrad
• RCS• Painting: 300 times
144π mm.mrad• Extraction: <81π mm.mrad
• MR• Injection: 81π mm.mrad• Extraction: 10π mm.mrad
@ 30 GeV
adiabatic dumping
Bunching Scheme @ J-PARC• Tomizawa Scheme• RCS : h=2 w/ empty bucket• MR : Empty bucket Scheme
• h=9 or h=8• Bunched Slow Extraction
MECO @AGS
Extinction (1st test)•Inter buchet: 10-6•Empty bucket: 10-3
2nd test (7.4GeV) : 10-7Transitionによる悪化?J-PARC/MR: Transition 無
1st test@ 24GeV
空バケツ法
空バケツの作り方
RFチョッパーダンプのビームによる熱負荷Empty Bucket へのRFチョッパーによる漏れ込み
Emittance Control• Adiabatic dumping ∝ 1/βγ
• NP-Hall Acceptance: 10π(24π) mm.mrad• 30 GeV : 10π → 8 GeV : 34π!!??
• Vertical: Reduce RCS painting area• Horizontal: 遅い取り出しならば < 5π mm.mrad
• in Tomizawa Scheme• 高加速繰返し• 低バンチ当たり粒子数: 低 space charge
• 小 RCS painting area、小3-50BT・MR コリメータ
Tomizawa Scheme
Extra Extinction Devices
Bunch Cleaner•AC-dipole•Fast Kicker場所はある@J-PARC/MR
External Extinction Dev.•AC-dipole•fextinction ~ 1/100
Muon Beam Line
Pion Production• Pion Production Target
• Graphite : 60cmL, 4cmφ
• 2 kW energy dissipation for 56 kW
• He gas cool
• Backward Extraction• Reduce high-p π-b.g.• Reduce heat-load to
solenoids
p t (G
eV/c
)
pl (GeV/c)
pt (GeV/c)pt (GeV/c)
p (GeV/c)
π production rate
MELC, MECO idea
Pion Capture
• pt → pl
• Parallel beam for p selection downstream
• yields : 0.05 (π+μ)/proton
Proton beam
100030
0
1400
3600
target
Z position along solenoid axis (cm)
Magne
tic fie
ld (Te
sla)
0
2
4
6
0 100 200 300
W shield
SC Coil
μ-yield vs. Bmax
π-Solenoid• Heat Load
• 2 kW @ target• 35 kW @ W Shield
• ΔE density : 2 × 10-5 W/gbehind W shield• 20cm-Cu SC coil : 1 kW
MECO design
• Design goal < 100 W• 2 × 3cm-Al SC coil : 10 W
• B = 5T, D = 300mm• 12.3 MJ, 12.5 kJ/kg
10-1310-1210-1110-1010-910-810-710-610-510-410-3
Energy deposition (GeV/g/1ppp)
z position (cm)
radi
al p
ositi
on (c
m)
0
20
40
60
80
0 100 200 300
MARS simulation
Al
5
30
NbTi/Cu
30 mm × 5 mmNbTi 1.28 mm diameter32 strandsNbTi: Cu: Al = 19%: 34%: 46%density: 4.0 g/cm3
Muon Beamline
0123456
0 5 10 15 20 25 30s(m)
Bs(Tesla)
s(m)
By(Tesla)
-0.2-0.15-0.1-0.05
00.050.10.150.2
0 5 10 15 20 25 30
Capture Sol.Matching Sol.
Curved Sol.1 Curved Sol.2Decay Sol.
Target Sol. Curved Sol. Detector Sol.
D[m] =1
0.3!B[T ]! s
R!
p2l + 1
2p2t
pl
•Guide π’s until decay to μ’s•Suppress unwanted particles
•μ’s : pμ< 75 MeV/c•e’s : pe < 100 MeV/c
Vertical Drift in Torus
Compensative Vertical B
Muon Beamline Optimization
0
0.002
0.004
0.006
100 125 150 175 200 225 250 275 300 325
0.02
0.04
0.06
0.08
0.1
x 10-2
100 125 150 175 200 225 250 275 300 325
Inner radius of transport solenoid (mm)
Num
ber o
f muo
ns /
prot
on
AllPµ>75MeV/cPµ<50MeV/c
Inner radius of transport solenoid (mm)
Num
ber o
f sto
pped
muo
ns /
prot
on
Inner radius of transport solenoid (mm)
Num
ber o
f muo
ns (P
µ>7
5MeV
/c) /
pro
ton
10-5
10-4
10-3
100 125 150 175 200 225 250 275 300 325
• Compensative Vertical B• 0.038 T and 0.052 T
• R = 175 mm• L = 15 m (baseline)
• yields : 0.002 μ’s/proton• 0.0002 (pμ > 75 MeV/c)• 10-5 π’s/proton
Detector
Curved Solenoid Spectrometer
Curved Solenoid Spectrometer• Moderate μ-Stopping ε
• ε=0.29 (Geant4 MC)• 0.0007 μ-stops/proton
• Compensative vertical B• Select 105 MeV e-
0123456
0 5 10 15 20 25 30s(m)
Bs(Tesla)
s(m)
By(Tesla)
-0.2-0.15-0.1-0.05
00.050.10.150.2
0 5 10 15 20 25 30
Capture Sol.Matching Sol.
Curved Sol.1 Curved Sol.2Decay Sol.
Target Sol. Curved Sol. Detector Sol.
Pµ(MeV/c)
(mu
on
s/0
.5M
pro
ton
s/4
Me
V/c
)
020406080
100120140
0 20 40 60 80 100 120
Muon momentum dist.
Muon Stopping Target• Light material for delayed measurement
• Aluminum : τμ- = 0.88 μs• Thin disks to minimize energy loss in the target
• R = 100 mm, 200μmt, 17 disks, 50 mm spacing• Graded B field for a good transmission in the downstream curved
section.
s(m)
Bs(Tesla)
0
0.5
1
1.5
2
2.5
3
3.5
16 16.25 16.5 16.75 17 17.25 17.5 17.75 18
5 cm
80 cm
2.43 T
1.90 T
20 c
m
98 100 102 104 1081060
500
1000
2000
3000
4000
Pe (MeV/c)
1500
IDEntriesMeanRMS
200 14874
104.2 0.7730
3500
2500
Electron Transmission
• Use torus drift for rejecting low energy DIO electrons.• rejection : 10-7~10-8, < 1kHz
• Good acceptance for signal e’s• 30~40%
0 20 40 60 80 100Momentum (MeV/c)
Acce
ptan
ce0.1
0.2
0.3
0.4
0.5
0.6
0
Transmission efficiency
Eth (MeV)0 20 40 60 80 100
DIO
/Sto
ppin
g-µ
10-12
10-10
10-8
10-6
10-4
10-2
Detector solenoid Traget solenoidCurved solenoidspectrometer
Collimator
105MeV/c60MeV/c
30MeV/c
Top view Side view
Decay-in-Orbit
Electron Detector• Rate < 1 kHz• Straw-tube tracker layers
• σp = 230 keV/c• Trigger calorimeter
98 100 102 104 106 108Pe (MeV/c)rec
0
100
200
300
400
500
600
700
800
Signal region
IDEntriesMeanRMS
202 3820
104.1 0.8589
Cosmic Ray Veto• Passive Shield• Active Shield
• Double layers of scintillator: 99% each• 計測時間に比例
• やばくなったらスピル長を縮める。
Detector Acceptance &Signal Sensitivity
AcceptanceGeometrical Acc. 0.73
Electron Transport 0.44Energy Selection 0.68pt > 90 MeV/c 0.82
Timing cut 0.38Total 0.07
100 ns 700 ns
1.17 µs
Timing Window of Detection
Proton Intensity 4 × 1013 HzRunning Time 2 × 107 sec
μ’s yields per proton 0.0024μ-stopping efficiency 0.29
Total 5.6 × 1017 stopped μ’s
B(µ! + Al! e! + Al) =1
Nµ · fcap · Ae
•Nμ = 5.6 × 1017
•fcap = 0.6 for Aluminum•Ae = 0.07•B(μ- + Al → e- + Al) = 4 × 10-17
< 10-16 (90% C.L.)
BackgroundBackground estimates for 10-16
*: assuming the extinction 10-9
Straw-man’s Layouts
J-PARCNP-Hall
DRAFT
Toward full PRISM
StoppingTarget
ProductionTarget
Phase-1:R<10-16
5 m
PRISMPhase Rotated Intense Slow Moun source
PRIMEPRISM Muon to Electron conversion experiment
Pion DecayMuon Transport
FFAGPhase-Rotator
Muon-Stopping Target
Proton Beam
PRIMEDetector
Pion Capture
Full PRISM:R<10-18
•Same Beam line, Detector•Replace Target & π-Cap. Solenoid•Add FFAG Phase -Rotator•Fast-Extracted Proton Pulse
Full PRISM at NP-HallFast Extraction (to NP-Hall) Scheme exist
• Add 2 kickers• Slow bump ON, E Septum OFF, M Septum all ON• Need more study, but promising.
•Precise measurement•Target A dependency
•Interaction type•By-products
MECO,mu2e and Phase-1MECO mu2e Phase-1
Machine BNL/AGS FNAL/Debuncher J-PARC/MREnergy 7.5 GeV/c 8 GeV/c 8 GeV/cPulse 1.4 μs 1.7 μs 1.1 μs
Extraction Bunched Slow ← ←Target Tungsten ← Graphite
Muon Beamline Curved Solenoid ← Curved Solenoid+ Vertical Field
μ stop 1011 muons/s ← 1011 muons/sDetector Straight ← Curved
Rate 500 kHz/wire ← 300 DIO tracks/sSensitivity 10-16 ← ←
Upgradability NO Project-X PRISM(10-18)
Japan & Fermilab:Collaboration work on pulsed-proton beam
AC-dipole, Extinction Monitor, etc.
まとめ• μ-e電子転換過程はc-LFVの一つであり、μ→eγやμ→eeeと共に重要なテーマである。
• LHCの後でもその重要に違いは無い。• BR=10-16 での μN→eN をJ-PARCで実行するべく準備中である。• LoI提出済み:P21
• 現在プロポーザル準備中• web page: http://nasubi.hep.sci.osaka-u.ac.jp:8080/prime/
• コラボレーターを募集しています。一緒にμN→eN をやりませんか。
End of Slides