Search for Muon to Electron
Conversion at J-PARC:COMET Phase-I Experiment
MyeongJae Lee(Institute for Basic Science, Korea)
Sep 25, 2017, NUFACT 2017

Sep 25, 2017

M.J.Lee, COMET Phase-I, NUFACT2017

2Muon LFV_

Note : μ-→e-νeνμ

μ+→e+g••

MEG (PSI)
MEG upgrade(planned)

Sep 25, 2017

μ-N→e-N

μ+→e+e-e+•

Mu3e(PSI, planned)

M.J.Lee, COMET Phase-I, NUFACT2017•••

Mu2e (FNAL)
DeeMe (J-PARC)COMET (J-PARC)
3

Muon Conversion: μ - N → e - N
µ
q

?
g

e

µ

q

q

Signal••?

eq

Background

Muon stops at Al (or Ti)
target, captured in 1s orbit
Decay with monoenergetic electron•

Decay-In-Orbit (DIO)•

Prompt background (tobeam arrival)– E = mµ – Erec –EB ~ 105MeV
Muon
mass

Sep 25, 2017

– Muon/pion decay in flight– Radiative pion capture:
πN→γX; γ→e+e– Cosmic, Anti-proton…

M.J.Lee, COMET Phase-I, NUFACT2017

4

Stopped µ- in matter• Muon capture :61% (Al)– µ + p ! ⌫µ + n– Muon decay
coherently with
nucleus– Source of
background hits

• Muonconversion– µ +N !e +N– µ !e ⌫¯e ⌫µ• Decay in orbit(DIO) : 39% (Al)– (Dynamically) freedecay of muon
inside atom
– E(e,max,Al)~< mµ ~ 104MeV(peak at 50 MeV)

nµ

W-

µ-

nµ

W-

µ4fm

e_
ne

– Muonconversion
coherently with
nucleuse-µg, Z0 , H ...

~2 n~0.1 p~1 g

Sep 25, 2017

e

0.04Å
20fm

M.J.Lee, COMET Phase-I, NUFACT2017

5

COMET Experiment
Pion Capture Section
A section to capture pionswith a large solid angle
under a high solenoidal
magnetic field bysuperconducting magnet

Pion-Decay and MuonTransport Section
A section to collect muons
from decay of pions undera solenoidal magnetic
field.
Sep 25, 2017

M.J.Lee, COMET Phase-I, NUFACT2017

COMET Phase-II

For R~10-17 muon conversion
measurement• 56 kW proton beam
• 1 year DAQ

Detector Section
A detector to search formuon-to-electron
conversion process
6

COMET Experiment
Pion Capture Section
A section to capture pionswith a large solid angle
under a high solenoidal
magnetic field bysuperconducting magnet

Transport Section
Pion decays to muon, with
momentum and charge
selection

Detector Section

COMET Phase-II

For R~10-17 muon conversion
measurement• 56 kW proton beam
• 1 year DAQCOMET-Phase-I
For BG measurement,
R~10-15 muon conversion• 3.2kW proton beam
• Half year DAQ

A detector to search formuon-to-electron
conversion process

Sep 25, 2017

M.J.Lee, COMET Phase-I, NUFACT2017

7

Facility / Beams

Fast eXtraction

1.17μsCOMET

8GeV, 3.2kW pulsed proton beam in Phase-I, 4/9 (or 3/9) buckets filled in MR
Sep 25, 2017

M.J.Lee, COMET Phase-I, NUFACT2017

8

Experimental Principle(1)Main proton pulse(2)Proton beam(3)Muon lifetime(4)Event timing

6. COMET
Muon Beam
Phase-I Muon Beam Line(1)protondetector system(3)muonpion production
system(2)pion(4)electronmuon transport system

COMET Phase-I detector：

Sep 25, 201716
About 10COMET muon beam-line：–

M.J.Lee,
COMET Phase-I, NUFACT2017
9

Figure 26: Overview of the COMET Phase-I Muon Beam line.

muons are stopped in

1. Protons arrive at
production target
2. Pions and muonsarrive at stopping
target
3. Captured muon decay
with finite lifetime
4. Some time after
muon beam arrival,
electron is measured• Any other beam
particles in this time
window arebackgrounds

6x10 muon/sec with 3kW beam

Bunch beam with highextinction factor
9

Pulsed Proton Beam(= at the end of RF plateau)•••

Beam Power
EnergyAverage current
Beam EmittanceProton/bunch
Extinction
Bunch separation
Bunch length

3.2 kW8 GeV
0.4 µA
10p mm･mrad
<1010
10-9
1~2 µs
100ns

Pulsed proton beam
– Beam background with proton pulse is major BG hit source– High extinction between beam enables localizing signal event in time

~10-11 extinction factor measured by increasing MR RF voltage (May2014), both at 8GeV and 30GeV, in Fast Extraction (@ Abort line)
More test with Slow Extraction early next year

Sep 25, 2017

M.J.Lee, COMET Phase-I, NUFACT2017

10In addition to the existing beam line (A-line) from the MR, a new beam line is being built(B-line). The B-line will serve both high-momentum (up to 30 GeV) experiments and COMET(8 GeV) and will have two branches: one from the A-line, and a second between COMET andthe high-momentum experiments. During the standard high-momentum running the A-line
and B-line share the beam in the ratio of 10,000:1. In the low-momentum running for COMET
the entire beam is sent to the B-line. The schematic of the beam lines are shown in Figure 5.1.
It is noted that the proton beamline is common for COMET Phase-I and Phase-II.

Accelerator Facility
after

J-PARC
Hadron hall
A-lineB-lineShielding wall of
COMET beam line
COMET
Hall

Switching magnet installation (2016)

under construction

Figure 5.1: The A and B-lines from the MR into the NP Hall. A schematic of the COMET experimentis shown in the bottom right.

5.1.

Switching yard (2014)
BranchbetweenA- and B-line– Almost
ready

COMET proton beam line (2016)– Under construction

To realize multiple operation modes, a Lambertson magnet followed by two septum magnets
will be deployed to provide the A/B-line branches. Figure 5.2 shows the cross section of the27

Sep 25, 2017

M.J.Lee, COMET Phase-I, NUFACT2017

11

Solenoids• Transport Solenoid• Pion Capture Solenoid– Ready, test and installation,alignment– Downstream parts ready,Upstream parts this andnext year– All SC wires preparedProton Monitor/Target

onproton
of
3T
e
id

Proton monitor• Measure the beam profile/extinction in front of the capture solenoid• Use the innovative diamond detector• High radiation tolerance & Fast time response• First beam test for diamond prototype is ongoing @J-PARC MR Geometry of proton monitor• Clear signals synchronized with beam bunch observed• Proton target• Final batch of superconducting cable for the• Graphite(or SiC)/Tungsten target for Phase-I/Phase-II
Pion Capture Solenoid has been delivered.
• Geometry optimized to increase the stopping muon yields,
R=13mm, L=700mm•

pion
5T Production
Superconducting Cable

for CS0ng TS1a – • Mandrel
coil winding waspleted.
alreadyinof CS0 coil is prepared
FY2016.
ding
this year. Target prototype
Y. Fujii coils@ CLFV2016
MS2
Sep 25, 2017
ocessedDiamond prototype detector

@
line
ort
Ab

AR
J-P

R
CM

Scintillator signal
inside beam pipe

13

M.J.Lee, COMET Phase-I, NUFACT2017

12

Cylindrical
Detectorsystem( Detector for muon conversion search )Superconducting
Coil
Cylindrical
Drift Chamber
Trigger scintillator+Cerenkov
detector

OM

CDC Pictures on 31st Aug.

Muon
stopping
target•••All stereo-wire drift chamber, 18
layers, ~5000 sense wires
Hodoscope for timing and trigger
Construction completed June 2016,
Cosmic ray test from August 2016

Sep 25, 2017

M.J.Lee, COMET Phase-I, NUFACT2017

13

CDC CR
test@
KEK
Event display w/o tra
Electronics Installation

CR test setup at KEK:
円筒型ドリフトチェンバー(CDC) 宇宙線テスト• Instrument
detector withHigh Voltage Side
iev
575
development DAQ
Spatialresolution
better than
• Triggerwith external
200μm
requirement
measuredCheckspatial resolution
forat
test layer(layer10)
hodoscope
counters
Signal check (1)from topcosmicrunand bottom.
RECBE installation• #1: trigger making• #2-5: upper region• #6-8: lower region

800
600

Center

800

600

400

400

200

200

200

0

0

0

10

Residual=drift distance– DCA*

− 200
2016/08/13
RECBE analog out
He:i-C4H10 (90:10)− 400

HV = 1700 V−200

Typical pulse height ~ 100 mV

Drift distance− 200*DCA (Distance Closest Approach)

−400

− 400

− 600

−600

− 600

− 800

−800

− 800

−800 −600 −400 −200

0

200

400

600

800
x [mm]

iev 545 High Voltage Side

−800 −600 −400 −200

0

200

400

600

800
x [mm]−800 −6

Center2016.8.13 最初宇宙線測定

HV = 1800 V

y [mm]y [mm]

Typical pulse height ~ 200 mV
Requirements for hit6+800
800• P value>0.05
600
600• # of Hits>14
400
400• # of layer which have single hit>14
平成28年8月からスタート
200
200• # of layers which havemulti hits<2
0

0

− 200

−200

Use events which P value is over 0.05
− 400

−400

− 600

−600

− 800

−800
−800 −600 −400 −200

0

200

400

600

800
x [mm]COMET CM22 @J-PARC

M.J.Lee, COMET Phase-I, NUFACT2017
Event
CDC
meetingNamey [mm]

The first cosmic-ray/01234567＝spatial resolution＋Tracking error
signal was observed !!

2017/5/30

800

600

400

Sep 25, 2017y [mm]y [mm]y [mm]•

Spatial resolution

800
600
400

17

$%&'()*+,= 166.m

200

e

0
− 200
− 400
− 600
− 800

−800 −600 −400 −200

0

8

200

400

600

800
x [mm]

5−800 −614

et GeometryCTH: Trigger Hodoscope

CyDet Geometr••

Twisted, overlapped
two scintillators + two Cerenkov detectors
1mm CFRP
Primary hit rate too high for trigger
4

Average rate @200 ~ 1170 ns (MHz)•Upstream
Scintillator

Upstream
Cherenkov

Downstream
Scintillator

Downstream
Cherenkov

3.5

1.5 - 24

3Adding lead shielding, require 4-fold coincidence for trigger: primary trigger rate 20 – 30 kHz

Sep 25, 20172016/1/7

M.J.Lee, COMET Phase-I, NUFACT201715

Trigger / DAQ

Table 30: List of GBT links for FC7 and FCT.

AMC Edgeconnector

Inbound

SFP+ for FC7
connection

DAQ
Triggerdata
DataPrototype
COTTRI•

Two COTTRI prototype boards arrived at KEK Figurein the end
the last month!
177:of Photographof the prototype FCT board.

•

Small delay w.r.t. the original schedule

COTTRIfor online trigger
implementation– Central system based oncommercial CERN productand a custom interface board– Ensuring commonality ininterfacing with different systems.

DisplayPorts

LEMO out

XilinxK7
FPGA

Triggerdecision

The SFP+ housing for the GBT fibre is at theleft and FPGA is to the right of this. The empty space along the right edge is for the 400-pin FMC connwhich
ismountedontheopposite
side
of
the
board.
InfiniBand

Analog in

XilinxA7
FPGA

LEMO in

FPGA

detector and gathering any BUSY signals when necessary to prevent further triggers. Some int
Analoginputsboardsalso gather
the trigger information for transmission to the FC7 (see below). In mostthese andboardsare reasonably straightforward and do not require FPGAs. These boards will ha
ADC
identifying number
hard-wired
into their connectors, allowing the FCT board to know which det
ADCs
it is handling.

150
DisplayPorts

4

SFP+

AnalogsignalCTH
Sep 25, 2017

Triggerdecision

M.J.Lee, COMET Phase-I, NUFACT2017

RECBE (Belle-II)• A configurable and flexible
Trigger system

Triggerdata

FCT– Mostly background hits
– Beam electron, secondary from
capture neutron/gamma– Online trigger suppress BG hits

FC7 (CMS)• High trigger rate (20-30 kHz) for
DAQ

Name
Number of GBT lines
Fast control: Trigger
1
Fast control: BeamTime
1
Fast control: SignalWindow
1
Fast control: PreBeamTime
1
FastSDRAM
control: SpillWindow
1
FMC slot1 1
Fast control: Busy(back)
Fast control: HardReset (12 MGT links)
1
Fast control: Spare1for IO expansion
Fast control: TimingPulse0
4
XilinxFast control:
TimingPulse1
4
Generic writeK7
interface
96
Status flag: FPGA fault
1
FPGA
slot2 1
Status flag: Wrong boardFMC
ID
Status flag: Busy
1
(8 MGT links)
Status flag: Data line active
1
for IO expansion
Status flag: Spares
4
Spare
8
μC (back)
Generic read interface32
as MMC
Trigger data64
Total (Inbound/Outbound)112

FMC (back)Direction
OutboundTriggerdata

Analogsignal

CDC
16

Straw - Electron Calorimeter
Detector ( Detector for background measurement )(&$/3URWRW\SHRYHUYLHZR&D Status•

StrEcal•Beam measurement program at Phase-I(&$/PRGXOHV– Detector for Phase-II– 5 station of straw detectors+ ~2000 LYSO
calorimeter– Particle composition, beam profile– 1/1000 reduced beam

9DFXXPJDXJH

9DFXXP3XPS• no radiation tolerance, pile-up issue.

– CyDet rolls out and StrEcal installed
Sep 25, 2017•

Single crystal optimizations•

2

0D\

2 Phase-I, NUFACT2017
M.J.Lee, COMETWK&20(7&0(&$/3URWRW\SH6WDWXV17

Integrated Beam Test for StrEcal•••

H.Nishiguchi(KEK)

StrECAL Overview

COMET CM22250

σ~180keV/c

200
150
100

Expected Position Resolution vs Position for Ar/C2H6=50/50, 2000V

Expected Position Resolution um

Sigma um

Sigma vs Position for Ar/C2H6=50/50, 2000V
300

150

100

0
0

0
0

Figure 11.37:

1.5

2

2.5

3

3.5

4
4.5
5
Position mm

σE/E~4.2%

200

50

1

Ideal Position Resolution
Timing Resolution Effect
Ideal & Timing Resolution
Track Position Resolution
Multiple Scattering
Total

250

50
0.5

•

300

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Position mm

Incident position dependence of the obtained spatial resolution, gas mixture =Sep
M.J.Lee,
COMET Phase-I, NUFACT2017
Ar/C25,(50/50), HV = 2000 V. (Left) Data, (Right) Garfield++
simulation
2 H62017

Integrated test withbeam at Tohoku univ.
Mar 2016 and Mar
2017
Including– One Straw chamber
prototype– 8x8 LYSO calorimeter– MIDAS DAQ– DRS4 based RO– Trigger based on
FC7+GBTAll successful operationand test, data underanalysis– Preliminary data
matches with prototype
tests
18

CDC BG Rejection, Reconstruction• Signal / BG hit discrimination using BDT– Signal efficiency = 0.99, when BG rejection = 0.95
– 1/20 BG hit reduction : trigger rate = 1 ~ 2 kHz• Signal / BG event discrimination– Signal efficiency = 0.90, when BG rejection = 0.95
– Hardware implementation on trigger system underrves, it seemsdevelopment
the rebinning procedure has little effect on the high signal retention

while incurring a small penalty for signal efficiencies less that 95%. Overall, the wiretion performs well enough to continue to the layer level.

• Offline track reconstruction with Kalman filter

190: A 20% occupancy event in the CyDet. This is a projected view from the end-plate of the detector,
g in the direction of the beamline. The red circles are hits caused from background processes, while thercles correspond to hits from the signal electron whose track is roughly outlined by the large blue circle.
ll of these hits is scaled to the output of the wire-level BBDT. The remaining points are the inactivate

16.17:ROC COMET
curvesfor two
independentof layer-level GBDT, in full scale19(left).16:Sep
ROC
classifiersofM.J.Lee,
wire-level
BBDT,
in fullscale (left)classifiers
and25, curves
2017 for three independent Figure
Phase-I,NUFACT2017

ratio of B(µN → eN ) = 3.1 × 10−15 . A detailed descripti
the DIO electrons is presented in Section 18.1. In this st
Pe < 106.0 MeV/c, where Pe is the momentum of electro
vetosystem at theto
BS thissystem study,(BS-CRV).theWithcontamination
the assumption that thefrom
BS-CRValso hasa
AccordingDIO
elec
veto inefficiency of 10≠4 , a upper limit of backgroundcontribution
is obtained to be Æ 0.01 for−−sensitivityof theµphysics
N→
Nestimateconversion
3.1by×an1
aeventrunning periodof the COMET
Phase-I
run.eThisis currently of
limited

Physics sensitivity
6187
6188

• Net acceptance = 4.1%

6189
6190
6191
6192

available computing time, and can be improved once more computing resource is available.

Signal and DIO (BR=3 × 10-15)

Cosmic-ray run during and prior to the physics run It is noted that COMET will also be
0.18
able to directly measure the cosmic-ray induced background using data collected during the
J-PARC MR 0.16
spill off time.
1.2
It will be useful to have a cosmic-ray run with the complete COMET Phase-I detector (with
0.14
the CTH triggers), prior to the physics run without a proton beam (see Section 22.2.). This
cosmic-ray run
would provide an opportunity to study and determine any special arrangements
1
0.12
to suppress cosmic-ray backgrounds further.

– Online efficiency ~0.99– Geometric acceptance20.2.6 Summary of background estimations+ track quality ~0.18– 103.6 MeV < p < 106MeV : 0.93
– 700ns < t < 1170 ns : 0.3
6193
6194
6195

Integral over Pth upto 106.0 MeV/c

6186

Counts per 0.1 MeV/c

6185

0.1

0.08

6196

6197
6198
6199
6200

0.06

0.8

0.6

Table 20.8 shows a summary of the estimated backgrounds. The total estimated background0.4
is about 0.0320.04
events for a single event sensitivity of 3 ◊ 10≠15 with a proton extinction factorof 3 ◊ 10≠11 . If the proton extinction factor is improved, the expected background events are
0.02
0.2
further reduced.
0
101.5

102

102.5

103

103.5

104

104.5

105

105.5

106

0
≠15
Table 20.8: Summary of the estimated background events for a single-event
sensitivity
inMomentum[MeV/c] of 3 ◊ 10 101.5
COMET Phase-I with a proton extinction factor of 3 ◊ 10≠11 .

• Background = 0.032– RPC ~ 0.003– DIO ~ 0.01
– Cosmic <0.01• SES(Phase-I) ~ 3.1x10-15– SES(Phase-II) ~ 2.5x10-17
Sep 25, 2017Type
Physics

BackgroundEstimated events
Muon decay in orbit
0.01
Radiative muon capture
0.0019−Figure 163: Left:
Distributions of the reconstructed <µ0.001
N →e
Neutron emission after muon capture
events. The verticalscale emission
is normalized
so that the integrated
Charged particle
after muon capture< 0.001−15
Prompt Beam
* Beam electrons
branchingratio of
B(µN
→
eN
)
=
3.1
×
10
.
Right:The inte* Muon decay in flightsignals and DIO*events
asinaflightfunction of the low side of the integr
Pion decay* Other The
beam particles
range is 106 MeV/c.
momentum window for signals is sele
All (*) Combined
Æ 0.0038
that the DIO contamination
Radiative pion capturewould be 0.01 events.
0.0028
Neutrons≥ 10≠9Delayed Beam Beam electrons≥0
Muon decay in flight≥0
Pion decay in flight≥0
Radiative pion capture≥0
Anti-proton induced backgrounds
0.0012OthersCosmic rays†< 0.01
Total
0.032

16.1.4

Time window for signals

The muons stopped in the muon-stopping target have thThis estimate is currently
limited by computing
resources. The µ− N →of muons in †aluminium
is about
864 nsec.
between the proton pulses to avoid beam-related backgr
backgrounds would come late after the prompt timing, s
M.J.Lee, COMET Phase-I, NUFACT201720
the time window for search is chosen to start at some tim

LNV physics: µ--e+ Conversion
4⇥ Br(RMC) ⇥ P !e +e+⇥ PEe+ >Emin ⇥ E,

(5)branching ratio of RMC whoser than Emin , P !e +e+ is theduction, PEe+ >Emin is the probfrom the pair production has anin , and PV ⇢T is the probability
vertex is located inside the stopT is supposed to be considered
the pair production vertex is loing target can be avoided by usf the trajectory of the daughter
her probability that internal conh an o↵-shell photon. Since there
tudies on the energy spectrum ofe internal conversion, the amountrvatively assumed to be the same
ckground through this paper.
ections, simulation studies using
d out with a muon-stopping tarand target nucleus candidates,

3

Events / ( 0.5 )ed positrons from RMC (NRM C )zed by120 × 10

27

110

Al

100
90
80
70
60
50
40
30
90.5

91

91.5

92

92.5

93

93.5
94
Ee+ (MeV)

Nµ-stop = 1018, BR(µ-e+)=1.7x10-12
FIG. 1. Fitted energy histogram of the µe+ signal (redand short dashed line) stacked on the on-shell RMC photon
background (blue and long dashed line). Br(µe+ ) is set
to 1.7 ⇥ 10 12 . Black dots represent the randomly generated
positrons from the background and signal composite model.

Candidate for muon stopping target•

Similar process with 0nbb in eµ sector•

Experimentally simple but hard to achieve good sensitivity

e: aluminum target

timation, It is required to know
unctions (PDF) of positrons fromversion and RMC, including theirf PDF, i.e., Nµ e+ and NRM C .
rons was obtained by generating
h the energy of Eµ e+ in the alutarget. The muon-stopping tar17 flat disks whose radius is 100
m, and the spacing between disks
hmarked the design of COMET
of positrons was measured after
et to consider the energy loss inf (Eµ e+ x), where f (x) is thebution, was used to fit the signal
he fitted PDF was normalized to
ned by the value of Br(µe+ ),nd E of 10 2 were assumed based
he upcoming experiments.
by generating 107 photons withve 90.30 MeV (Emin ) inside alu. Simulation result showed that
⇢T is 0.0058, and PEe+ >Emin ise value of 6.22 ⇥ 10 7 in the enMeV to 101.85 MeV according to
By plugging these values into Eq.
o be 6.24 ⇥ 105 without considerions of the o↵-shell photons. For
ons, another simulation was done
nough samples of positrons from•– Provides clues in LNV and Majorana n– Another physics case with COMET Phase-I detector
RMC. The RMC photons of 2⇥106 with the same energy
range were generated inside the large size of aluminumin which almost half of photons decay with the pair production. The PDF of positrons from the pair productionend
was fitted to the power function of A(ERMx)y , whereC
A is the normalization constant, x is the positron energy,
and y is the fitted power of the function. The fitted PDF
end
was forced to be null above ERM
C , and normalized to
NRM C afterward.
For an illustrative purpose, Fig. 1 shows the estimation of the energy spectrum of the RMC backgroundfrom on-shell photons and the µe+ signal positronwith the Br(µe+ ) of 1.7 ⇥ 10 12 , which is the current limit. The energy distributions of signal and RMC
were convoluted with a Gaussian detector response function with 200 keV standard deviation. To estimate howmuch the sensitivity would be improved over the current
limit, the statistical significance of the signal with a givenBr(µe+ ) was examined using a maximum likelihood
method. The systematical uncertainties were assumed
to be negligible. With this assumption, Br(µe+ )that has 3 significance under the null hypothesis wasfound to be 2.5 ⇥ 10 13 . When the internal conversionsof RMC are included, Br(µe+ ) of 3.5 ⇥ 10 13 wasfound to have 3 significance. These results imply thatsensitivity improvement of more than a factor of ten may
not be achieved, which requires at least Br(µe+ ) of
1.7 ⇥ 10 13 .

– By flipping charge– RMC background dominates

Replacing Al target to other nuclei may allow O(104)sensitivity improvement (arXiv:1705.07464)

Sep 25, 2017

M.J.Lee, COMET Phase-I, NUFACT2017

21

Schedules• Highly recognized by KEK IPNS, stage-2 of COMET Phase-I
approved (i.e. project full funded, beam will be delivered)• Phase-I physics data taking in 2019
– Depending on budget allocation– Cosmic run at 2018, 4 weeks of engineering run– 5 month data taking• Phase-II R&D in parallel with Phase-I R&D and data taking• Phase-II physics data taking in 2021~2022– 1 year data taking

Proton beamline
Solenoid
Detector Construction/ Installation2016

Sep 25, 2017

2017

CR
run

2018

M.J.Lee, COMET Phase-I, NUFACT2017

COMET
Phase-I
Operation

2019

22

Proto-collaboration• 107 collab
Summary…
New members
areinstitut
117 c
25
•
LPNHE, France
27
collaborators
University, Japan
12• 107 Kyushu
11
countri•
New members
areinstitutes
117 collaborators
25•-15
LPNHE, France
27 institutes• SES : 3.1 x 10107
collaboratorsJapan
12 countries• Kyushu University,
11
countries•– SES (Phase-II @~2022):
New members
areinstitutes
117 collaborators
25•
2.5 x 10-17
LPNHE, France
27 institutes
University, Japan
12 countries• Start data takingKyushu
at 2019• 11 countries
High K.
EnergyAccelerator
Research M.
Organization
Tsukuba,
Japan T. Mibe,
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Malaya,Budker Institute of Nuclear Physics (BINP), Novosibirsk, Russia

Tbilisi, Georgia

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Ogits

Md. I. Hossain
Numao Malaysia
UniversityT.
Technology

TRIUMF, Canada
T. Numao
TRIUMF, Canada

164 col
37 institutes

164 collaborators
37
institutes,
12 countries
S.Mihara, J-PARC PAC Meeting, 16/Mar/2012

Tbilisi, Georgia
Collegeof Natural* Contact
PersonScience, National
T. OtaVietnam University, Vietnam
H.-B. Li, C. Wu, Y. Yuan
S. Dymov, P. Evtoukhovich, V. Kalinnikov, A. Khvedelidze, A. Kulikov,
Max-Planck-Institute(Werner-Heisenberg-Institute),
M. Aoki, T. Hiasa, for
I.H.Physics
Hasim T.
Hayashi, Y. Hino, S. Hikida, T. Munchen,
Itahashi, S.Germany
Ito,Institute of High Energy Physics (IHEP), China
G. Macharashvili, A. Moiseenko, B. Sabirov, V. Shmakova, Z. Tsmalaidze Y. Kuno∗ , T.H. Nam, H. Nakai, H. Sakamoto, A. Sato, N.D. Thong, N.M. Truong
Joint Institutefor Nuclear Research(JINR),I.Dubna,
Y. Mori, Y. Kuriyama, J.B. Lagrange
A. Liparteliani,
N. Mosulishvili,
Yu. Tevzadze,
Trekov,Russia
N. Tsverava

164 collaborators
37 institutes, 12 countries
S.Mihara, J-PARC PAC Meeting, 16/Mar/2012

Institute of High Energy
PhysicsA.ofDrutskoy,
I.JavakhishviliStateE.University
M. Danilov,
V. Rusinov,
Tarkovsky(HEPI TSU), Tbilisi,
Georgia
Institute for Theoretical and Experimental
Physics (ITEP), Russia
S. Dymov, P. Evtoukhovich, V. Kalinnikov,
A. Khvedelidze, A. Kulikov,
T. OtaMax-Planck-Institutefor PhysicsB.(Werner-Heisenberg-Institute),
Munchen, Germany
G. Macharashvili,
A. Moiseenko,
Sabirov, V. Shmakova, Z. Tsmalaidze,
E. Velicheva
Joint Institute for Nuclear Research (JINR), Dubna, Russia

K. Okamoto29 , C. Omori15 , T. Ota31 , H. Owen22 , C. Parkes22 , J. Pasternak11
C
1N
V. Ponariadov4 , A. Popov6, 28 , V. Rusinov13, 23 , A. Ryzhenenkov6, 28M,
2 In
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N
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, Z.
14
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Y. Yang19 , H. Yoshida29 , M. Yoshida15 , Y. Yoshii15 , T. Yoshioka19 , Y. Yuan
J. Zhang2 , Y. Zhang2
1 North China Electric Power University, Beijing, People’s Republic

Y. Mori, Y. Kuriyama, J.B. Lagrange

2 Institute of High Energy Physics (IHEP), Beijing, People’s Republic

Kyoto
University
ReactorInstitute,E.Kyoto,
Japan
M. Danilov,
A.Research
Drutskoy,
V. Rusinov,
Tarkovsky
Institute for Theoretical and C.V.
Experimental
Physics (ITEP), Russia
Tao5

3 Peking University, Beijing, People’s Republic of China B
4 Belarusian State University (BSU), Minsk, Belarus

College of Natural Science, National Vietnam University, Vietnam

T. OtaMax-Planck-Institute(Werner-Heisenberg-Institute),
M. Aoki, T. Hiasa, for
I.H.Physics
Hasim T.
Hayashi, Y. Hino, S. Hikida, T. Munchen,
Itahashi, S.Germany
Ito,

5 B.I. Stepanov Institute of Physics, National Academy of Sciences of Belarus

6 Budker Institute of Nuclear Physics (BINP), Novosibirsk, Rus

Y. Kuno∗ , T.H. Nam, H. Nakai, H. Sakamoto, A. Sato, N.D. Thong, N.M. Truong

7 Charles University, Prague, Czech Republic

Y. Mori, Y. Kuriyama, J.B. Lagrange

8 The Cockcroft Institute, Daresbury Laboratory, Warrington, U
20 Laboratory
9 Czech Technical University, Prague, Czech Republic

S.Mihara, J-PARC PAC Meeting, 16/Mar/2012• Half year data taking for– Muon conversion
measurement– Beam measurement

10 Indian Institute of Technology, Bombay, India
11 Imperial College London, London, UK

13 Institute for Theoretical and Experimental Physics (ITEP), Ru

14 Joint Institute for Nuclear Research (JINR), Dubna, Russi

15 High Energy Accelerator Research Organization (KEK), Tsukuba
16 King Abdulaziz University, Saudi Arabia

17 Institute for Chemical Research, Kyoto University, Kyoto, Ja

18 Research Reactor Institute, Kyoto University, Kyoto, Japa
19 Kyushu University, Fukuoka, Japan

20

20 Laboratory of Nuclear and High Energy Physics (LPNHE), CNRS-IN2P3 La
an

COMET Collaboration meeting@KEK 26-30 Jan 2015

and Marie Curie (UPMC), Paris, France
21 National Centre for Particle Physics, Universiti Malaya, Kuala Lump

176 collaborators,
33 institutes, 15 countries• … and the Future?

Sep 25, 201721 Nat12 Institute for Nuclear Science and Technology, Hanoi, Vietna

M.J.Lee, COMET Phase-I, NUFACT201723

• Beam Energy Selection• 68 MeV/c ±3%• at extraction of the muon
storage ring.

-19… and the Future up to O(10 )Capture  Solenoid“PRISM/PRIME” or something…
Matching  Section
Solenoidase

Injection  System

Ejection  System

C-­shaped
FFAG  Magnet

FFAG  ring

Detector

RF  Cavity
RF  AMPRF  Power  Supply

5  m• x(1/2) from reduced beam
acceptance from solenoid
to FFAG• x3 from removing
detection time window (nopion)• x3 from pion capture
improvement• x20 from 56 kW→1MW

1
10-1
10-3
10-5
10-7
10-9
10-11
10-13
10-15

~2x10-17

10-17
10-19
1940

Sep 25, 2017

1950

1960

1970

1980

1990

2000

2010

2020

2030

x10~100
improvement?!

• Multi GW beam
• PRISM (Phase RotatedIntense Slow Muon source)

M.J.Lee, COMET Phase-I, NUFACT2017

24

Backups

Sep 25, 2017

M.J.Lee, COMET Phase-I, NUFACT2017

25

Cosmic ray / Neutron• To suppress Cosmic Ray muon tofactor of 10-4
– Decay in flight, interaction with detectormaterial– Note: CDC can full-reconstruct CR• Neutron issue– SiPM weak to neutron irradiation,
generates noise at Strip sensor– Internal Neutron Shield reduces neutronfrom stopping target– Similar neutron flux expected from proton
target, shielding around beamline understudy
Sep 25, 2017

M.J.Lee, COMET Phase-I, NUFACT2017

26

Probing O(104) TeV
mass scale,èMuch higher
energy scale than
LHC

DipoleInteraction
µ
q

?
g

Λ (TeV/c2)

μN→eN vs μ→eγ
A. de Gouvea and P. Vogl,
Prog. In Particle and Nuclear
Physics 71 (2013) 75

Mu2eContact
interaction

MEG (2013)

e

µ

q

q

MEG (2011)

SINDRUM-II (2006)

?

e
q

κ

X
mµ

µ⌫
LCLF V =µ̄R µ⌫ eL F +µ̄L µ eL (q̄L µ qL )22
(1 + )⇤(1 + )⇤q=u,dSep 25, 2017

M.J.Lee, COMET Phase-I, NUFACT2017

27