Transcript mN-eN Rare Process

2 pages of DeeMe
μ- + N → e- + N
Forbidden in the Standard Model
Discovery will be a significant result:
Evidence of the new physics beyond the SM
Answer to the light neutrino mass
Complementary to the LHC
MEG Goal
Current Upper Limits (SINDRUM-II@PSI)
BR[μ- Ti→ e- Ti] < 4.3 × 10-12, BR[μ- Au→ e- Au] < 7 × 10-13
Little Higgs
Branching ratios could be different between light/heavy nucleus.
Theory Predictions: BR = 10-12~10-17
SUSY
B(μ→e conv) > 10-14
photonic: ~ BR(μ→eγ) ×O(α) ~ 10-14
non-photonic: cannot study with μ→eγ
MEG(PSI): BR[μ→eγ] < 2.4 × 10-12 –on going
Extra Dim.
COMET/Mu2E: BR[μ-e conv.] < 10-16 – planned(2019~)
DeeMe(J-PARC MLF): BR[μ-e conv.] ~ 5×10-15
Aiming to start from 2015.
photonic
non-photonic
DeeMe
Search for μ-e conversion electron directly emerging out of the primary target.
H-line @MLF
DeeMe
Nμ- stopped @ the primary target (graphite@2009): ~1010 /sec/MW
Spectrometer
Hodoscope
Plan of the experiment
Replace the existing Graphite target with SiC.
Extract delayed electrons with 105 MeV/c of the beam momentum by H line
Precisely measure the electron momentum with a spectrometer.
g-2/EDM
Tracker
Sensitivity：S.E.S. = 5 × 10-15 (8×107 sec)、MLF runs 2×107 sec per year.
Can run completely independent of T2K, hadron-hall experiments, neutron experiments,
muon experiments with D-, U-, S-lines.
surface-μ
H-line with large acceptance: H-line can be used for g-2/EDM experiments.
Good for the effective use of J-PARC facility: maximize the outputs from J-PARC.
Focus Solenoid
Prompt Kicker
Focus Solenoid
Bend Mag.
Capture Solenoid
Pulsed Proton Beam
SiC Rotation Target
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Cost and Schedule
Item
Cost (kJPY)
sub total Note
Detector
103,000
Spectrometer Magnet
30,000
Hodoscope
10,000
WC R&D
(73,000)
gating-grid type
3,000
WC Construction
50,000
Readout Electronics
10,000
Target
30,000
SiC Target
30,000
H-Line Construction
Facility
Prompt Kicker
220,000
Magnet
60,000
Power Supply
160,000
PostDoc (3)
15,000/y
75,000
Total
428,000
2011
Design
Grant-in-Aid submit
H-Line const.
Upstream
Downstream
Kicker
Detector
Run
Analysis
Multi-purpose beamline:
Can be used for other
experiments
2012
2013
2014
2015
4
Many pages of DeeMe
Experimental Search
for μ-e Conversion in Nuclear Field
at Sensitivity of 10-14
with Pulsed Proton Beam from RCS
--- DeeMe --M. Aoki, Osaka University
on behalf of DeeMe Collaboration
MuSAC 2012/2/18
DeeMe Collaboration
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M. Aoki(1), Y. Miyake(2), K. Shimomura(2), N. Kawamura(2),
P. Strasser(2), S. Makimura(2), M. Kinsho(3), K. Yamamoto(3), P.K. Saha(3),
H. Kobayashi(3), H. Matsumoto(3), C. Ohomori(3), M. Ikegami(3),
M. Yoshii(3), S. Mihara(4), H. Nishiguchi(4), K. Yoshimura(4),
N. Saito(4), T. Mibe(4), D. Bryman(5), T. Numao(6)
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(1) Osaka University
(2) KEK MUSE
(3) KEK Accelerator
(4) KEK IPNS
(5) UBC
(6) TRIUMF
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Muon in the Standard Model of
Particle Physics
• There are three generations (flavors) of
Quarks and Leptons.
• Muon was found at 1936.
–
I.I. Rabi said “Who ordered that?”
• Is the muon excited state of electron?
–
–
The world-first search for muon rare process:  > e @1947
Null Result → a hint of generation
• BRtheory( ->e)~10-4 @ 1958
–
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But exp. already gave
BRexp. < 2 x 10-5
→ Two neutrinos model
•  e ≠   @1962 BNL
–
Toward the establishment of the concept of
“generation/flavor”.
• (g-2)μ@BNL hints physics beyond the
Standard Model
Muon played very important role in the development of particle physics.
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flavor of elementally particles
Leptons
Quarks
• Quark Mixing
u
c
t
d
s
b
e



?
?
e


– Cabbibo-Kobayashi-Maskawa (CKM)
Matrix
– Established --- Novel Prize@2008
• Neutrino Mixing
– Pontecorvo-Maki-Nakagawa-Sakata
(PMNS) Matrix
– Homestake, Kamiokande, SNO etc.
– Observed and Established.
• Charged Lepton Flavor Violation
(CLFV)
– No observation yet at all.
– Implemented to the Standard Model of
Particle Physics as “forbidden”.
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 -eConversioninNuclearField
• Muonic Atom (1S state)
Muon Capture(MC)

nuclei
Muon Decay in Orbit (MDO)
– MC:MDO = 1:1000(H), 2:1(Si), 13:1(Cu)
– τ(free μ-) = 2.2 μs
– τ(μ-;Si) = 0.76 μs
• charged Lepton Flavor Violation (CLFV)
μ-e Conversion in Nuclear Field
Clear evidence of the new physics
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Physics of μ-e Conversion
•
SUSY-GUT, SUSY-seesaw (Gauge Mediated
process)
BR = 10-15 = BR(μ→eγ) × O(α)
τ→lγ
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SUSY-seesaw (Higgs Mediated process)
BR = 10-12~10-15
τ→lη
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Doubly Charged Higgs Boson (LRS etc.)
Logarithmic enhancement in a loop diagram
for μ-N → e-N, not for μ→e γ
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M. Raidal and A. Santamaria, PLB 421
(1998) 250
Little Higgs Models
Randall-Sundrum Models
SUSY with R-parity Violation
Leptquarks
Heavy Z’
N
N
Relations with other observables
G. Ishidori et al., PRD 75 (2007) 115019
Recent Upper Limits
SINDRUM-II: BR[μ- + Au → e- + Au] < 7 × 10-13
SINDRUM-II: BR[μ- + Ti → e- + Ti] < 4.3 × 10-12
TRIUMF: BR[μ- + Ti → e- + Ti] < 4.6 × 10-12
μ→eγ vs. μ-e conversion
MEG Goal
Little Higgs
SUSY
B(μ→e conv) > 10-14
Extra Dim.
photonic-like
nonphotonic-like
Principle of Measurement
SINDRUM II
• Signal : μ- +(A,Z) → e- +(A,Z)
– A single mono-energetic electron
• 105 MeV
• Delayed：~1μS
• No accidental backgrounds
• Physics backgrounds
– Muon Decay in Orbit (MDO)
• Ee > 102.5 MeV (BR:10-14)
• Ee > 103.5 MeV (BR:10-16)
– Beam Pion Capture
• π-+(A,Z) → (A,Z-1)* → γ+(A,Z-1)
γ → e+ e• Prompt timing
SINDRUM II Results
BR[μ- + Au → e- + Au] < 7 × 10-13
BR[μ- + Ti → e- + Ti] < 4.3 × 10-12
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μ-e electrons may directly coming from a production target.
an electron analogue of the surface muon.
Experiment could be very simple, quick and low-cost.
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DeeMe
• Process : μ- +(A,Z) → e- +(A,Z)
– A single mono-energetic electron
• 105 MeV
• Delayed：~1μS
• No accidental backgrounds
• Physics backgrounds
– Muon Decay in Orbit (DIO)
• Ee > 102.5 MeV (BR:10-14)
• Ee > 103.5 MeV (BR:10-16)
•Low Energy main part: suppressed by the
– Beam Pion Capture
• π-+(A,Z) → (A,Z-1)* → γ+(A,Z-1)
γ → e+ e• Prompt timing
•Main pulse: Kicker to reduce the detector rate.
•after-protons: Suppressed owing to the
beamline.
•High Energy tail: Magnet Spectrometer (Δp <
0.3%)
extremely small after-protons from RCS -RAP<10-17.
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After-Proton (beam related) BG
mu-e conversion
J-PARC MLF Muon Facility
H-line
•1 MW : 3 GeV, 333 μA
•High statistics
•Pulse Beam: 25 Hz 50 pulses
•Low backgrounds
Proton Beam
Proton Target
•
the 1st concept by Jaap Doornbos (TRIUMF)
– multi purpose beamline
• DeeMe + g-2 + muonium-HFS
– large acceptance
• > 110 msr
– straight section for kickers and a separator.
– moderate Δp so that the BG’s can be monitored
simultaneously.
• DIO backgrounds (p < 102.5 MeV/c)
• Prompt backgrounds (p > 105.0 MeV/c)
Detailed design is ongoing by MUSE/IMSS/J-PARC.
Not fully optimized yet
DIO BG
Signal
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Beamline: H-line
Prompt BG
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Target Material
•
•
fMC: muonic nuclear-capture rate
– (1-fMC)=ffree-decay --- useless muons: large fMC is
better: larger Z.
On the other hand, τμ- > 300 nsec (light Z) to avoid
the prompt background
•
fC: Fraction of the atomic capture of muon to the
atom of interest
– single-element material: fc = 1
– composite material: proportional to Z (FermiTeller Z law)
• Silicon-Carbide --- Si:C = 7:3
•
Silicon-Carbide:
– good thermal shock resistance: ΔT=450°C
– high melting point: >1450°C
– good radiation resistance
• 10 dpa @ 1000°C or more
Silicon Carbide
• CERASIC
target material
fC × fMC
Graphite
0.08
Silica-carbide (SiC)
0.46
SiC Muon Target: 6 times higher physics sensitivity!!!
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Sensitivity and Backgrounds
DIO BG
• Signal Sensitivity
μ-e signal
– S.E.S.: 2×10-14 (for 2×107sec of run)
• Backgrounds
Beam BG
– Assuming RAP=10-19
(based on the recent R&D)
– Detector live-time Duty = 1/20000
Signal Region: 102.0 -- 105.6 MeV/c
or much less
• If we could extend the running-time up to 8×107 sec
– Standard Cut: S.E.S.= 0.5 × 10-14 (NBG=0.48)
– Tighter Cut: S.E.S.= 0.6 × 10-14 (NBG<0.02)
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In-situ Monitoring
of Backgrounds
Moderate Δp of H-line makes it possible to monitor
backgrounds in situ.
– DIO backgrounds (p < 102.0 MeV/c)
– Prompt backgrounds (p > 105.6 MeV/c)
Background Monitoring
– DIO electrons
• shape
• yield
– Prompt Backgrounds
• p>105.0 MeV/c (direct upper limit)
• Beam-loss counters in RCS
– Cosmic-induced Backgrounds
• Beam-on: 50μsec/sec
• Beam-off: >500msec/sec
DIO BG
Signal
Signal Sensitivity Calibration
– Calibrated by using number of DIO electrons.
– NDIO=300 (2e7 sec)
Prompt BG
(Prompt BG)
Signal
Cosmic BG
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R & D Items
• H-line
– Large Acceptance (> 110 msr)
• Kicker
– Large Aperture (320-mm × 320-mm)
– High Field > 385 G
– Fast fall < 300 nsec
• After-protons from RCS
• SiC Target
– Impact on the downstream of the primary.
• Detector
– Drift Wire Chamber: that can be operated after 33k of the prompt
burst.
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Detector
• prompt burst = 33k per pulse
even after suppressed by the kicker.
• BH1,2: hodoscope
– gating PMT
– Designed by T. Taniguchi,
but he passed away.
– Development is suspended.
• WC1-4: wire chamber
– micro-cell or asymmetric-cell
– Doable, but may need further R&D
• Amp. and readout FADC system.
• σ < 0.3 MeV/c
gating PMT
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After-Protons from RCS
STR+BPM
STR+BPM
RCS
Pulse KM
1~3
•
QFL
Pulse KM
4~8
QDL
Excellent design of RCS transverse acceptance
– RCS ring aperture = 486π mm.mrad
ring collimator aperture = 350π mm.mrad
– Extraction Beamline aperture = 324π mm.mrad
– Total kick angle = 17 mrad --- > 2000π mm.mrad
•
Fast Extraction Scheme (not a slow extraction)
•
Preliminary measurement of a beam-loss monitor
showed promising result: RAP could be < 10-19.
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Improved measurement will be performed in next
February, 2012.
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Preliminary
Measurement
•
after-protons are scattered
protons.
•
beam-loss counters can observe it.
•
258 hours of measurement.
by Kazami Yamamoto
•
No evidence of the after-protons
so far. Measurement is limited by
the electrical noise from the RCS
kickers.
•
The above snapshot gives
•
RAP could be ~ 10-19
•
•
It is required to be < 10-17
The detectors will be improved for much
better measurement in future.
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Cost and Schedule
Item
Cost (kJPY)
Detector
sub total Note
103,000
Spectrometer Magnet
30,000
Hodoscope
10,000
WC R&D
(73,000)
gating-grid type
3,000
WC Construction
50,000
Readout Electronics
10,000
Target
30,000
SiC Target
Multi-purpose beamline:
Can be used for other
experiments
30,000
H-Line Construction
Facility
Prompt Kicker
220,000
Magnet
60,000
Power Supply
160,000
PostDoc (3)
Total
15,000/y
2011
2012
2013
75,000
428,000 2014
2015
Design
Grant-in-Aid submit
H-Line const.
Upstream
Downstream
Kicker
Detector
Run
Analysis
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Status
• KEK/IMSS Muon PAC: Stage-1 approved.
• J-PARC PAC: pre Stage-1, aiming to get Stage-1.
• The lab already started the procurement of magnets in the
tunnel of H-Line.
• Kicker design: talking with Nippon-Koshuha for the detailed
cost estimate. We also are communicating with BNL C-AD
department.
• Gas wire chamber development is on-going.
• The 2nd stage of the after-proton measurement is ongoing.
• KAKENHI (Kiban S) application was submitted.
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Summary
•
There is a competitive merit of physics in searching for μ-e conversion at
sensitivity of 10-14 in timely manner.
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Needless to say that the result should be obtained before the result from COMET
and/or Mu2e.
•
It will maximize the potential of major discovery at J-PARC.
•
The experimental idea with which the physics result can be obtained within 5
years was proposed. It fits the research period of Grant-in-Aid for Scientific
Research of Japan.
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It is necessary to build a large-acceptance beamline (H-line) for the best result.
The H-line can be time-shared with other experiments, such as g-2.
•
After protons are much smaller than that required from the experiment.
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The size of cost (except for the multi-purpose H-line) is within the range of the
Grant-in-Aid for Scientific Research of Japan.
•
R&D activities are on-going.
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End of Slides
Ring aperture ( w/ magnets only)
Begin
Ext. Ins
315
320
Varying x or x’ at the starting
x: ±32mm (~315) ~ ±92mm(~2600)
x’:±6.5mrad (~320) ~ ±16mrad(~2000)
1st Foil
Secondary (~350
Collimators
キッカーの役割
•
RCSからの陽子パルスに同期したprompt burst
– 50M particles/pulse (2009年テスト実験実測)
• 検出器が飽和してしまう。
– キッカーでpromptタイミングのみ<1/1000に減らす。
• 検出器レート 33k particles/pulse
注: 遅延粒子の量は大げさに図示してある。
磁場
> 385 Gauss
Gap
320 mm
Width
320 mm
Length
400 mm
台数
4台
Fall Time
< 300 nsec
繰り返し
25Hz
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Transmission Efficiency
Internal Inductance = 100 nH
Magenta: kicker current
Green: mu-e signal strength @ birth
Blue: mu-e signal @ detector
Internal Inductance = 500 nH
-10% --- acceptable
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キッカーコンセプトUpdate
Internal inductance
By H. Matsumoto (KEK)
Magnet
Impedance matching elements
INTERNAL
INDUCTANCE
FALL TIME @ 500 A
100 nH
307 nsec
300 nH
361 nsec
500 nH
430 nsec
MAGNET COIL CURRENT [A]
10 kA
500 A
FALL TIME
1) MAGNET INDUCTANCE: 600 nH
2) IMOEDABCE MATICHING ELEMENT: 8000 pH, 100 Ohm
3) MAGNET COIL CURRENT: 10 kA
4) PFL IMPEDANCE: 5 Ohm
MAY. 06, 2011
[email protected]
日本高周波とコンタクト
Test Measurement
How many μ- are actually stopping
in the production target?
J-PARC MLF Muon Facility
Counters at the exit of D-Line
Pb (4mmt)
D2 Exit
μ-
e-
Plastic Scintillator
•
•
•
B1: gating-PMT readout
B2: gating-PMT readout
B3: ND filter (1/1000),
normal PMT readout
B1 B2
B3
•Count only after the prompt beam-burst (>104/pulse).
•Can’t close a beam slit to reduce the beam rate. Otherwise, it takes forever
to accumulate the enough number of events.
use gating-PMTs that can be turned-off during the prompt beam-burst.
•Beam μ- will produce delayed hits if they stop in the plastic scintillator.
Pb plate to absorb μElectron detection efficiency ~ 50% @ 40 MeV/c
Analysis
• Record PMT signals by using500MHz FADC like E787/949.
• Subtract a baseline template from the recorded waveform.
• Maximum hight of the pulse tagged by the other counter shows
clear valley between pedestal and signal.
– The detection efficiency is sufficient.
• Real hits by the beam particles = B1*B2
– τ = 2.10±0.02 μs
B1 pulse height
(B2 tagged)
B2 pulse height
(B1 tagged)
– Combination of τμ+(2.2μs) and τμ--C(2.0μs). There is a
contamination coming from e- produced by e+ scattering
where the e+ is from Michel decay of μ+ in the target. The
number of stopped μ+ is 450 times more than that of μ-.
e- from e+ scattering
e- ~ e+/450
P Spectrum
• 検出器のdetection efficiencyは鉛板の影響により、低エネルギ
ーで落ち込むはず。
• pe > 40 MeV/cでは μ-崩壊からのe-が支配的
• pe ~ 50 MeV/cのMichel Edgeは確かに Michel Edge
• pe < 30 MeV/cではμ+崩壊からのe+の散乱e-が支配的
• この効果を補正すると
→ μ- stopping rate = 5 × 109 /sec/MW in the current Target.
• G4では 7 × 109 /sec/MW
e- from e+散乱
e-
gating PMT
• No. of particles in a prompt pulse
~1e4
• Standard PMT is saturated.
• Used a gating PMT system
– off/on gain ratio = 1e6
Designed by Taniguchi
Snapshot of PMT signal
•B1
•Plas. Scinti.
•gating
•B2
•Plas. Scinti.
•gating
•B3
•Plas. Scinti.
•normal PMT
•ND filtered
Baseline distortion due to delayed fluorescence from plastic
scintillator.
Individual hits by real particles can be seen on the baseline.
G4Beamline Estimation
G4Beamline model of D2 beam line
28 MeV/c μ• Geometrical Acceptance:40 msr（point source）
Yield: 4.4 counts/pulse/100-kW @ detector
→ 5 × 109 /sec/MW in the Muon Production Target.
Geant4 MC: 7 × 109 /sec/MW
for SiC Rotation target: 1010/sec/MW
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Jaap’s H-line Design
muonium branch
g-2 branch
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Some Experimental Observations
delayed fluorescence from
the plastic scintillator
kicker
extinction < 6 x 10-7
limited by BG from muon decay outside
no hits / 109 total protons -> extinction < 10-9
Statistics Limited
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DeeMe @ J-PARC MLF
mu-e conversion
DeeMe
COMET
Sensitivity
Schedule
~10-14
<10-16
~2015
2017~
DeeMe does not replace COMET.
DeeMe will gain momentum of muon-CLFV research field.
Sound scenario to secure the world-first discovery.