j p ar c pw e 8õa sgîg !!! prism/pha se · why staging, why 10-18 • staging • early...

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

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




FFAGPhase-Rotator


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


Num

ber o

f sto

pped

muo

ns /

prot

on


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




FFAGPhase-Rotator


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

j p ar c pw e 8õa sgîg !!! prism/pha se · why staging, why 10-18 • staging • early...

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