[PPT] - - e conversion @J - PARC --- COMET --- Koji Y oshimura, KEK on PowerPoint Presentation

SLIDE 1

μ-e conversion 実験 @J-PARC

-- COMET ---

Koji Y

shimura, KEK
n behalf of COMET collaboration

Most slides were inherited from Aoki-san’s talk at JSPS Meeting 素粒子実験領域、素粒子論領域、ビーム物理領域合同シンポジウム J-PARCにおけるミューオン素粒子物理実験

SLIDE 2

The COMET Collaboration (as of October 16, 2008)

D. Bryman

Department of physics and astronomy, University of British Columbia, Vancouver, Canada,

R. Palmer

Department of Physics, Brookhaven National Laboratory, USA,

E. Hungerford

Department of Physics, University of Houston, USA

Y. Iwashita,

Institute for Chemical Research, Kyoto University, Kyoto, Japan

V. Kalinnikov, A. Moiseenko, D. Mzhavia, J. Pontecorvo, B. Sabirov, Z. Tsamaiaidze,

and P . Evtukhouvich JINR, Dubna, Russia

M. Aoki, Y. Arimoto, Md.I. Hossain, T. Itahashi, Y. Kuno, A. Sato, and M. Yoshida

Department of Physics, Osaka University, Japan

J. Sato, M. Yamanaka

Department of Physics, Saitama University, Japan Y, Takubo, Department of Physics, Tohoku University, Japan

Y. Igarashi, S. Ishimoto, S. Mihara, H. Nishiguchi, T. Ogitsu, M. Tomizawa,
A. Yamamoto, and K. Yoshimura

High Energy Accelerator Research Organization (KEK), Japan

T. Numao

TRIUMF , Canada new in red

SLIDE 3

The (quasi) COMET Collaborators

A. Kurup, (and Y. Uchida)

The Blakett Laboratory, Imperial College London, UK

T. Ito

Los Alamos National Laboratory, USA, (not sign in yet but participate in the meetings and even do simulation works.) for the UK, Oxford University, University College London, Glasgow University and other UK Universities. and is planning a LFV workshop in the UK in November for France, Orsay and Saclay.... and is planning a seminar trip in French institutes in November for Switzerland, ETH Zurich and PSI and is attending a Swiss Workshop in November for Italy, Germany and Spain not yet....

The COMET collaboration is approaching to ....

SLIDE 4

Muon Task Force, Muon Working Group and the COMET collaboration

COMET collaboration Muon g-2 Japan Group Muon Working Group

(discussing Japanese activities of muon particle physics)

KEK Muon Task Force

SLIDE 5

Contents

Introduction
What is mu-e conversion
Physics of c-LFV (brief for experimentalist)
How to measure mu-e conversion
COMET
Pulsed Proton Beam
Pion Production and Capture
Muon T

ransport and Muon Stopping Target

Curved Solenoid Spectrometer
Sensitivity and Background
COMET to PRISM
Summary

SLIDE 6 6

Muonic Atom (1S state)
MC:MDO = 1:1000(H), 3:2(Al), 13:1(Cu)
τ(free μ-) = 2.2 μs
τ(μ-;Al) = 0.88 μs
μ-e Conversion

nuclei

µ−

Muon Decay in Orbit (MDO) charged Lepton Flavor Violation (c-LFV)

μ-e Conversion

Muon Capture(MC)

BR[µ− + (A, Z) → e− + (A, Z)] ≡ Γ[µ− + (A, Z) → e− + (A, Z)] Γ[µ− + (A, Z) → νµ + (A, Z − 1)]

µ− + (A, Z) → e− + (A, Z)

SLIDE 7 7

charged Lepton Flavor Violation (c-LFV)
Forbidden in the SM
μ-+A→e-+A , μ→eγ, μ→eee, τ→e(μ)γ, τ→e(μ)h ...
Neutrino-mixing predicts very small amount of c-LFV via higher
rder diagram; it is as small as practically impossible to observe

in foreseeable future.

c-LFV = Physics beyond SM with neutrino oscillation

charged Lepton Flavor Violation

A. de Gouvea

SLIDE 8

Physics of μ-e Conversion

SUSY-GUT, SUSY-seesaw (Photon 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

SLIDE 9

Physics of μ-e Conversion

SUSY-GUT, SUSY-seesaw (Photon 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

SLIDE 10 9

c-LFV and SUSY

Physics of slepton mass matrix SUSY

  m2

˜ e˜ e

∆m2

˜ e˜ µ

∆m2

˜ e˜ τ

∆m2

˜ µ˜ e

m2

˜ µ˜ µ

∆m2

˜ µ˜ τ

∆m2

˜ τ ˜ e

∆m2

˜ τ ˜ µ

m2

˜ τ ˜ τ

 

c-LFV slepton mixing

SLIDE 11 10

Theoretical Predictions

Process Current Limit SUSY-GUT level 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 COMET COMET tanβ=3 tanβ=10 tanβ=30

SLIDE 12

  m2

˜ e˜ e

∆m2

˜ e˜ µ

∆m2

˜ e˜ τ

∆m2

˜ µ˜ e

m2

˜ µ˜ µ

∆m2

˜ µ˜ τ

∆m2

˜ τ ˜ e

∆m2

˜ τ ˜ µ

m2

˜ τ ˜ τ

 

Golden T rio

e ̃ e ̃ B ~ mixing large top Yukawa coupling ̃ ̃

̃

̃

c-LFV

g-2 EDM

Real Imaginary

τ-LFV

slepton mass matrix

SLIDE 13 12

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

BR < 7 × 10-13

SLIDE 14

COMET @ J-PARC

Pulsed Proton Beam
π-b.g. suppression
Large μ yields
J-PARC/MR
nly 60 kW out of 450kW
π-capture SC-solenoid
1011 μ/s (PSI:108 μ/s)
Curved-solenoid detector
Lower detector rate
Upgradability to PRISM
add Phase-Rotator-Ring

Detector Section Pion-Decay and Muon-Transport Section Pion Capture Section A section to capture pions with a large solid angle under a high solenoidal magnetic field by superconducting maget A detector to search for muon-to-electron conversion processes. A section to collect muons from decay of pions under a solenoidal magnetic field. Stopping Target Production Target

SLIDE 15

Physics Capabilities of mu-e

J-PARC PAC report about COMET US P5 Report

SLIDE 16

Pulsed Proton Beam

Backgrounds
π-+(A,Z) → (A,Z-1)* → γ+(A,Z-1)，γ → e+ e- : Prompt
μ- decay-in-flight, e- scattering, neutron streaming
Signal
μ- +(A,Z) → e- +(A,Z) : Delayed (~1μs)

Nbg = NP×Rext×Yπ/P×Aπ×Pγ×A NP : 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

Arbitrary Unit 1 Prompt Background Stopped Muon Decay Main Proton Pulse 10 p/pulse 8 Timing Window ( μ s ) Time Signal 100 ns 1.1 μs

SLIDE 17

Pulsed Proton@ J-PARC

Tomizawa Scheme
RCS : h=2 w/ empty bucket
MR : Empty bucket Scheme
h=8
Bunched Slow Extraction

→ Next talk by Tomizawa-san for details.

SLIDE 18

Additional Extinction Means

Bunch Cleaner
in MR
tested at AGS for MECO
AC-dipole
@ primary beamline
fextinction ~ 1/100
collaboration with mu2e

−0 .05 −0 .04 −0 .03 −0 .02 −0 .01 0.01 0.02 0.03 0.04 0.05 5 10 15 20 25 30 L (m) x (m) −0 .05 −0 .04 −0 .03 −0 .02 −0 .01 0.01 0.02 0.03 0.04 0.05 5 10 15 20 25 30 L (m) y (m) B1 B2 Q1 Q2 Q3 Q4 Collimator Q5 Q6 Q7 Q8 B1 B2 Q1 Q2 Q3 Q4 Collimator Q5 Q6 Q7 Q8

SLIDE 19

Pion Production & Capture

Detector Section Pion-Decay and Muon-Transport Section Pion Capture Section A section to capture pions with a large solid angle under a high solenoidal magnetic field by superconducting maget A detector to search for muon-to-electron conversion processes. A section to collect muons from decay of pions under a solenoidal magnetic field. Stopping Target Production Target

SLIDE 20

Pion Production

low-E pions
for low-E muons to stop
Backward extraction
pion yield ∝ Tproton
pion yield ∝ Beam Power
High-Z Metal Rod
12-mmφ × 16-cm
3-4 kW on the target
W

ater cooling or Radiation cooling

SLIDE 21

Pion Capture

5 T at the target position
capture pt < 120 MeV/c
Radiation Shield

< 100 W on SC coil

3-4 kW @ target
35 kW @ W Shield
2×10-5 W/g @ coil
yields:

0.05 (π+μ)/8-GeV-proton

μ-yield vs. Bmax 10

13

10

12

10

11

10

10

10

9

10

8

10

7

10

6

10

5

10

4

10

3

Energy deposition (GeV/g/1ppp) z position (cm) radial position (cm) 20 40 60 80 100 200 300

MARS simulation

SLIDE 22

π-Capture Solenoid

Heat-load density : 2 × 10-5 W/g behind W shield
Utilize Al stabilized SC cable to reduce a heat load to the cold mass.
2-layers × 3-cmt Al SC coil : 10 W

(20cm-Cu SC coil : 1 kW)

B = 5T
80 A/mm2
load line ratio: 0.63
12.3 MJ, 12.5 kJ/kg

Al 5 30 NbTi/Cu

30 mm × 5 mm NbTi 1.28 mm diameter 32 strands NbTi: Cu: Al = 19%: 34%: 46% density: 4.0 g/cm3

Al-SC: one of world leading expertise of KEK

SLIDE 23

Muon Beamline and Muon Stopping Target

Detector Section Pion-Decay and Muon-Transport Section Pion Capture Section A section to capture pions with a large solid angle under a high solenoidal magnetic field by superconducting maget A detector to search for muon-to-electron conversion processes. A section to collect muons from decay of pions under a solenoidal magnetic field. Stopping Target Production Target

SLIDE 24

Muon Beamline

Guide π’s until decay to μ’s Suppress high-P particles

μ’s : pμ< 75 MeV/c
e’s : pe < 100 MeV/c

SLIDE 25

High-P Suppression

D[m] = 1 0.3 × B[T] × s R × p2

l + 1 2p2 t

pl

V ertical Drift in Torus

See “Classical Electrodynamics”, J.D.Jackson Ch.12-Sec.4 Momentum (MeV) 20 40 60 80 100 120 140 160 180 200 y (cm)

20
15
10
5

5 10 15 20 Beam-Muon Momentum vs. Y Position

δP/δx = 1 MeV/c/cm

SLIDE 26

Muon Stopping Target

Light material for delayed measurement
Aluminum : τμ- = 0.88 μs
Thin disks to minimize electron 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.
Good μ-Stopping efficiency: ε=0.3
stopped-muon yields:0.001-0.002 μ’s/proton
backgrounds:
0.0002 (pμ > 75 MeV/c)
10-5 π’s/proton

Pµ(MeV/c) (muons/0.5M protons/4MeV/c) 20 40 60 80 100 120 140 20 40 60 80 100 120

SLIDE 27

Curved Solenoid Spectrometer

Detector Section Pion-Decay and Muon-Transport Section Pion Capture Section A section to capture pions with a large solid angle under a high solenoidal magnetic field by superconducting maget A detector to search for muon-to-electron conversion processes. A section to collect muons from decay of pions under a solenoidal magnetic field. Stopping Target Production Target

SLIDE 28

Curved Solenoid Spectrometer

Torus drift for rejecting low energy DIO electrons.
rejection ~10-6: < 10kHz
Good acceptance for signal electrons
20%

60-MeV/c DIO electrons

D[m] = 1 0.3 × B[T] × s R × p2 l + 1 2p2 t pl

105-MeV/c μ-e electron

Electron Total Energy (MeV) 20 40 60 80 100 Transmission Efficiency 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 Transmission Efficiency

SLIDE 29

Electron Detectors

Rate < 10-100 kHz
Straw-tube tracker: 5 layers
σp = 230 keV/c
T

rigger calorimeter

GSO or PWO

Electron Momentum (MeV/c) 100 101 102 103 104 105 106 107 Events per 0.192 MeV/c

3

10

2

10

1

10 1 10 2 10 3 10 mu-e Conversion and Decay-in-Orbit Decay-in-Orbit mu-e Conversion Signal Arbitrary Unit 1 Prompt Background Stopped Muon Decay Main Proton Pulse 10 p/pulse 8 Timing Window (μs) Time Signal 100 ns 1.1 μs

SLIDE 30

Detector Acceptance & Signal Sensitivity

Acceptance Geometrical Acc. 0.74 Electron T ransport 0.32 pt > 52 MeV/c 0.66 χ2 Cut (χ2 < 9) 0.89 Energy Selection 0.52 Timing cut 0.38 Total 0.028 Cycle Time 1.5 sec 0.9 sec Proton Intensity 4 × 1013 Hz 7 × 1013 Hz Running Time 2 × 107 sec 2 × 107 sec μ’s yields per proton 0.004 0.004 μ-stopping efficiency 0.3 0.3 Total 1.1 × 1018 stopped μ’s 1.8 × 1018 stopped μ’s

B(µ− + Al → e− + Al) = 1 Nµ · fcap · Ae

Nμ = 1.8 × 1018
fcap = 0.6 for Aluminum
Ae = 0.028
B(μ- + Al → e- + Al) = 3.3 × 10-17

< 5 × 10-17 (90% C.L.)

SLIDE 31

Backgrounds

Background estimates for COMET *: assuming the extinction 10-9

Background Events Comments Muon decay in orbit 0.05 230 keV (sigma) assumed Pattern recognition errors <0.001 Radiative muon capture <0.001 Muon capture with neutron emission <0.001 Muon capture with charged particle emission <0.001 Radiative pion capture* 0.12 prompt pions Radiative pion capture 0.002 due to late arriving pions Muon decay in flight* <0.02 Pion decay in flight* <0.001 Beam electrons* 0.08 Neutron induced* 0.024 for high energy neutrons Antiproton induced 0.007 for 8 GeV protons Cosmic rays induced 0.1 with 10-4 veto inefficiency Total 0.4

SLIDE 32

COMET to PRISM

COMET:BR<10-16

5 m PRISM Phase Rotated Intense Slow Moun source PRIME PRISM Muon to Electron conversion experiment Pion Decay Muon Transport FFAG Phase-Rotator Muon-Stopping Target Proton Beam PRIME Detector Pion Capture

PRISM:BR<10-18

Same Beam line, Detector
Replace Target & π-Cap. Solenoid
Add FFAG Phase -Rotator
Fast-Extracted Proton Pulse

Detector Section Pion-Decay and Muon-Transport Section Pion Capture Section A section to capture pions with a large solid angle under a high solenoidal magnetic field by superconducting maget A detector to search for muon-to-electron conversion processes. A section to collect muons from decay of pions under a solenoidal magnetic field. Stopping Target Production Target

SLIDE 33

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

f factor 10 improvements
Why 10-18, why 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. V

empati PRD 74(2006) 116002 COMET

SLIDE 34

COMET and mu2e

COMET @ J-PARC mu2e @ Fermilab

Detector Section Pion-Decay and Muon-Transport Section Pion Capture Section A section to capture pions with a large solid angle under a high solenoidal magnetic field by superconducting maget A detector to search for muon-to-electron conversion processes. A section to collect muons from decay of pions under a solenoidal magnetic field. Stopping Target Production Target

J-PARC -- FNAL/Booster U-curve -- S-curve U-curve -- Straight

MELC → MECO →

SLIDE 35

mu2e and COMET

MECO mu2e COMET Machine BNL/AGS FNAL Booster+Debuncher J-PARC/MR Energy 7.5 GeV/c 8 GeV/c 8 GeV/c Pulse 1.4 μs 1.7 μs 1.2 μs Beam Power 56 kW 20 kW 50-100 kW Extraction Bunched Slow ← ← Extinction 10-9 ← ← Target Heavy Metal ← Heavy Metal Muon Beamline S-Curved Solenoid S-Curved Solenoid U-Curved Solenoid + V ertical Field μ stop 1011 muons/s ← 1011 muons/s Detector Straight Straight Curved Rate 500 kHz/wire 100 kHz/wire 10-100 kHz/detector Sensitivity 10-16 ← ← Upgradability NO Project-X PRISM(10-18)

SLIDE 36

Summary

μ-e conversion is a unique process that can allow us to study

TeV-scale physics.

J-PARC has capabilities to hosts a μ-e conversion experiment

and to world-leads muon particle physics.

COMET is an experiment searching for mu-e conversion

down to a level of 10-16 at J-PARC. A proposal of COMET was already submitted to J-PARC/PAC.

COMET collaboration is working hard to brush-up the design
f the apparatus.
A task-force in KEK is going to be formed to investigate the

location issue of COMET.

There is room you can still make major contributions. This is

a good chance to join the COMET collaboration.

Join COMET

SLIDE 37

End of Slides

SLIDE 38 37

LFV 探索の現状

Reaction 90% CL Upper Limit B( µ + → eγ ) 1.2 ×10 −11 B( µ + → e +e −e +) 1.0 ×10 −12 B( µ −Ti → e − Ti) 6.1 ×10 −13 B( µ −Pb → e − Pb) 4.6 ×10 −11 B( µ −Ti → e + Ca) 1.7 ×10 −12 P( µ +e − → µ −e +) 8.3 ×10 −11 B(τ →eγ ) 2.7 ×10 − 6 B(τ → µγ ) 1.1 ×10 − 6 B(τ → µµµ) 1.9 ×10 − 6 B(τ → eee) 2.9 ×10 − 6 B( KL → µe) 4.7 ×10 −12 B( K + → π +µ +e −) 2.1 ×10 −10 B( KL → π 0µ ±e ) 6.2 ×10 − 9 B( D 0 → µe) 8.1×10 − 6 B( D 0 → τe) 5.3 ×10 − 4 B( D 0 → φµe) 3.4 ×10 − 5 B( B → µe) 3.5 ×10 − 6 B( B → Kµe) 1.8×10 − 5 B( Z → µe) 1.7×10 − 6 B( Z → τe) 9.8 ×10 − 6 B( Z → τµ ) 1.2 ×10 − 5 Based on a table written by Y. Kuno Updated in August, 2000

ミュオンが大変健闘している

質量が比較的小さい為、大量に生成可能
統計を上げやすい
寿命が比較的長い
実験しやすい

SLIDE 39 38

µ-LFV 探索の歴史

1 0

1 4

1 0

1 2

1 0

1 0

1 0

8

1 0

6

1 0

4

1 0

2

1940 1950 1960 1970 1980 1990 2000 Upper limits of Branching Ratio Y e a r KL 0 → µe K + → πµe µA→eA µ → eee µ→ eγ After Y

shitaka Kuno
Since 1948

E.P . Hincks and B. Pontecorvo, PR 73 (1948) 257

µ稀崩壊探索の歴史

= µ-LFV探索の歴史 = フレーバー物理の歴史

μ→eγ未発見

==> 世代(フレーバー)概念

SLIDE 40

Slepton Mixing Mechanism

GUT Yukawa interaction Neutrino Yukawa interaction Quark mixing matrix Neutrino mixing matrix @ Plank mass scale

SUSY-GUT SUSY Seesaw Model

(m2 ˜ l )ij = m2 0δij (∆m2 ˜ l )ij = 0 (m2 ˜ L)21 ∼ 3m2 0 + A2 8π2 h2 tV ∗ tdVts ln MGUT MRS (m2 ˜ L)21 ∼ 3m2 0 + A2 8π2 h2 i U ∗ i1Ui2 ln MGUT MRS PRISM/Phase-1 LoI (2006)

SLIDE 41

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 find

SUSY particle

high-intensity exp.

comes forefront.

L. Calibbi, A. Faccia, A. Masiero, S.K. V

empati, PRD74(2006)116002

SLIDE 42

μ-LFV

μ→eγ μ→eee μN→eN

SLIDE 43

μ→eγ, μ→eee, μN→eN

L = mµ Λ2 µRσµνeLFµν + 1 Λ2

F

(µLγµeL)(eLγµeL) + 1 Λ2

F

(µLγµeL)(qLγµqL)

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

SLIDE 44 43

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

SLIDE 45 44

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

SLIDE 46

μ-e Conversion vs. μ → e γ

μ→e γ

only photonic
B(μ→e γ) = 200 × B(μ-N → e-N)
High intensity surface muon
Accidental Background
State-of-the-art Detector

Physics is complemental

Different Background Mechanism Different Technologies Experiments are also complemental

μ-N → e-N

photonic
non-photonic
No Accidental Background
Pulsed and/or Pure Muon Beam
State-of-the-art Beamline

SLIDE 47

MECO, mu2e, PRISM and COMET

SLIDE 48 47

MECO BNL/AGS

Straw 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

SLIDE 49 47

MECO BNL/AGS

Straw 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

SLIDE 50 48

Staging Strategy

On the evening before the MECO cancellation

5 m PRISM Phase Rotated Intense Slow Moun source PRIME PRISM Muon to Electron conversion experiment Pion Decay Muon Transport FFAG Phase-Rotator Muon-Stopping Target Proton Beam PRIME Detector Pion Capture !""# !""$ !""% !""& !"'" !"'' !"'! !"'( !"') !"'* !"'# !"'$ !"'% +,-.

/01234526/0

740 809:;161 <7=>+ ?@A@:/BC@02

/01234526/0

740

MECO:BR<10-16 PRISM:BR<10-18

SLIDE 51 48

Staging Strategy

On the evening before the MECO cancellation

5 m PRISM Phase Rotated Intense Slow Moun source PRIME PRISM Muon to Electron conversion experiment Pion Decay Muon Transport FFAG Phase-Rotator Muon-Stopping Target Proton Beam PRIME Detector Pion Capture !""# !""$ !""% !""& !"'" !"'' !"'! !"'( !"') !"'* !"'# !"'$ !"'% +,-.

/01234526/0

740 809:;161 <7=>+ ?@A@:/BC@02

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740

MECO:BR<10-16 PRISM:BR<10-18

SLIDE 52

Staging of PRISM

COMET:BR<10-16

5 m PRISM Phase Rotated Intense Slow Moun source PRIME PRISM Muon to Electron conversion experiment Pion Decay Muon Transport FFAG Phase-Rotator Muon-Stopping Target Proton Beam PRIME Detector Pion Capture

PRISM:BR<10-18

Detector Section Pion-Decay and Muon-Transport Section Pion Capture Section A section to capture pions with a large solid angle under a high solenoidal magnetic field by superconducting maget A detector to search for muon-to-electron conversion processes. A section to collect muons from decay of pions under a solenoidal magnetic field. Stopping Target Production Target

SLIDE 53

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 Line A-D Line

SLIDE 54

COMET

SLIDE 55

PRISM/Phase-1 Overview

Large μ yields
J-PARC/MR
nly 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

Detector Section Pion-Decay and Muon-Transport Section Pion Capture Section A section to capture pions with a large solid angle under a high solenoidal magnetic field by superconducting maget A detector to search for muon-to-electron conversion processes. A section to collect muons from decay of pions under a solenoidal magnetic field. Stopping Target Production Target

SLIDE 56

Pulsed Proton Beam

SLIDE 57

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

SLIDE 58

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

SLIDE 59

Emittance Control

Adiabatic dumping ∝ 1/βγ
NP-Hall Acceptance: 10π(24π) mm.mrad
30 GeV : 10π → 8 GeV : 34π!!??
V

ertical: 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

SLIDE 60

Tomizawa Scheme

SLIDE 61

Detector

SLIDE 62

Cosmic Ray V eto

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。

SLIDE 63

Detector Acceptance & Signal Sensitivity

Acceptance Geometrical Acc. 0.73 Electron T ransport 0.44 pt > 52 MeV/c 0.67 χ2 Cut (χ2 < 9) 0.86 Energy Selection 0.56 Timing cut 0.38 Total 0.04 100 ns 700 ns 1.17 µs Timing Window of Detection Proton Intensity 4 × 1013 Hz ← Running Time 4 × 107 sec 2 × 107 sec μ’s yields per proton 0.0024 0.007* μ-stopping efficiency 0.29 0.26 Total 1.1 × 1018 stopped μ’s 1.5 × 1018

B(µ− + Al → e− + Al) = 1 Nµ · fcap · Ae

Nμ = 1.1 × 1018
fcap = 0.6 for Aluminum
Ae = 0.04
B(μ- + Al → e- + Al) = 4 × 10-17

< 10-16 (90% C.L.)

*Tungsten Target + Beamline Update

SLIDE 64

Background

Background estimates for 10-16 *: assuming the extinction 10-9

SLIDE 65

Curved Solenoid Spectrometer

SLIDE 66

Straw-man’s Layouts

J-PARC NP-Hall

DRAFT

SLIDE 67

Full PRISM at NP-Hall

Fast 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

SLIDE 68

まとめ

c-LFVは大変重要な素粒子物理学の分野である。
μ-e電子転換過程はc-LFV過程の一つであり、μ→eγ

やμ→eeeと共に注目されている。

LHCの後でもその重要に違いは無い。
BR=10-16 で μN→eN を探索する実験をJ-PARCへ提案
COMET Collaboration
プロポーザル、2007/11/30に提出
web page: http://comet.hep.sci.osaka-u.ac.jp:8080/comet/

SLIDE 69

最後に

コラボーレター募集中です。
まだまだ、割り込む余地はたくさんあります。

SLIDE 70

End of Slides

SLIDE 71

Straw-man’s Cost Estimate

SLIDE 72

Muon Yield

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) Number of muons / proton All Pµ>75MeV/c Pµ<50MeV/c Inner radius of transport solenoid (mm) Number of stopped muons / proton Inner radius of transport solenoid (mm) Number of muons (Pµ>75MeV/c) / proton 10

5

10

4

10

3

100 125 150 175 200 225 250 275 300 325

muon yields:

0.002 μ’s/proton

backgrounds:
0.0002 (pμ > 75 MeV/c)
10-5 π’s/proton

SLIDE 73

Curved Solenoid Spectrometer

Moderate μ-Stopping ε
ε=0.29 (Geant4 MC)
0.0007 μ-stops/proton
Compensative vertical B
Select 105 MeV e-

1 2 3 4 5 6 5 10 15 20 25 30 s(m) Bs(Tesla) s(m) By(Tesla)

0.2
0.15
0.1
0.05

0.05 0.1 0.15 0.2 5 10 15 20 25 30 Capture Sol. Matching Sol. Curved Sol.1 Curved Sol.2 Decay Sol. Target Sol. Curved Sol. Detector Sol. Pµ(MeV/c) (muons/0.5M protons/4MeV/c) 20 40 60 80 100 120 140 20 40 60 80 100 120

Muon momentum dist.

SLIDE 74 71

μ-e Conv. Next Generation

Beam-induced prompt backgrounds:
Pulsed beam
Long Muon Beam Line
More muons:
1011 μ-/s (SINDRUM II: 108 μ-/s)
J-PARC/MR + Solenoid π cap.
Detector rate might be too high:
Low Rate Detector

SLIDE 75

Curved Solenoid Spectrometer

Torus drift for rejecting low energy DIO electrons.
rejection ~10-6: < 10kHz
Good acceptance for signal electrons
20%

20 40 60 80 100 Momentum (MeV/c) Acceptance 0.1 0.2 0.3 0.4 0.5 0.6

T ransmission efficiency

60-MeV/c DIO electrons

D[m] = 1 0.3 × B[T] × s R × p2 l + 1 2p2 t pl

105-MeV/c μ-e electron

SLIDE 76

V ertical Drift

もっと見栄えの良い絵がほしいところ。前ページとコンバインもしたい。

SLIDE 77 74

Quark Mixing : Kobayashi-Maskawa (KM) Matrix
Neutrino Mixing : Maki-Nakagawa-Sakata (MNS) Matrix
charged Lepton Mixing : μ→e, τ→μ, τ→e
charged Lepton Flavor Violation (c-LFV)

Flavor Mixing

s W − u Vus VKM =   Vud Vus Vub Vcd Vcs Vcb Vtd Vts Vtb   =   0.97383+0.00024 −0.00023 0.2272+0.0010 −0.0010 (3.96+0.09 −0.09) × 10−3 0.2271+0.0010 −0.0010 0.97296+0.00024 −0.00024 (42.21+0.10 −0.80) × 10−3 (8.14+0.32 −0.64) × 10−3 (41.61+0.12 −0.78) × 10−3 0.999100+0.000034 −0.000004  

sin2(2θ23) > 0.90 tan2(θ12) = 0.45+0.09

−0.07