1. Search for Non-Standard Model Physics
Using the Transverse Muon Polarization
in Stopped K+ Decay
The E06 TREK Experiment
Sébastien Bianchin
TRIUMF / University of British Columbia
on behalf of the TREK-E06 Collaboration
PANIC 2011 (July 24th – 29th, 2001)
Massachusetts Institute of Technology, MA, USA
Thursday, July 28th 2011
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2. The TREK Program at J-PARC
Outline
 TREK Program TREK = Time Reversal Experiment with Kaons
 Search for Time Reversal Symmetry Violation
 Test of Lepton Universality
 Search for Heavy Neutrinos Lower intensity
 Hadron Facility at J-PARC
 TREK Apparatus – R&D
 Status & Schedule
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3. Stopped K+ Experiments @ K1.1BR
P36 (LFU)
“Measurement of RK = (K+ →e+) / (K+ →m)
and search for heavy sterile neutrinos”
Stage-1 (PAC11-Jan’11); 30 kW (~2013)
(S. Shimizu, Parallel 5C – Meson Decays, July 28th @ 4pm)
E06 (TREK)
“Measurement of T-violating transverse muon
polarization (PT) in K+→0mdecay”
Stage-1, 270 kW (~2014)
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4. Stopped K+ Experiments @ K1.1BR
P36 (LFU)
“Measurement of RK = (K+ →e+) / (K+ →m)
and search for heavy sterile neutrinos”
Stage-1 (PAC11-Jan’11); 30 kW (~2013)
(S. Shimizu, Parallel 5C – Meson Decays, July 28th @ 4pm)
E06 (TREK)
“Measurement of T-violating transverse muon
polarization (PT) in K+→0mdecay”
Stage-1, 270 kW (~2014)
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5. Transverse m+ Polarization in the Km3 Decay
K+→mdecay
 PT is T-odd, and spurious effects from final state interaction
are small: PT (FSI) < 10-5
Non-zero PT is a signature of T violation

- Standard Model (SM) contribution to PT : PT (SM) < 10-7
PT in the range 10-3 – 10-5 is a sensitive probe of
CP violation beyond the SM.
There are theoretical models of new physics which allow
a sizable PT value without conflicting with other
experimental constraints.
The TREK experiment aims for a sensitivity of 10-4
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6. Expected Sensitivity
We are aiming for a sensitivity of PT ~ 10-4
 PTstat ~ 0.05 PTstat (E246) ~ 10-4 : 1.4 x 107 sec runtime
1) Beam intensity x 30
2) Detector acceptance x 10
3) Larger analyzing power
PTsyst ~ 0.1 PTsyst (E246)
~ 10-4
1) Precise calibration of misalignments
2) Correction of systematic effects
3) Precise fwd-bwd cancellation
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7. New Physics: Model Predictions for PT
Model K+  0m+ K+  m+
■ Standard Model < 10-7 < 10-7
■ Final State Interactions < 10-5 < 10-3
Multi-Higgs ≤ 10-3 ≤ 10-3
PT (K+  0m+) ≈ + 3 PT (K+  m+)
SUSY with squark mixing ≤ 10-3 ≤ 10-3
PT (K+  0m+) ≈ − 3 PT (K+  m+)
SUSY with R-parity breaking ≤ 4 x10-4 ≤ 3 x10-4
Leptoquark model ≤ 10-2 ≤ 5 x10-3
■ Left-Right symmetric model 0 < 7x10-3
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8. J-PARC Facility
(KEK/JAEA）
North
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9. J-PARC Facility
Linac (KEK/JAEA）
North
3 GeV
Synchrotron
CY2007 Beams
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10. J-PARC Facility
Linac (KEK/JAEA）
North
3 GeV
Synchrotron
Materials and Life
Experimental
Facility
CY2007 Beams Hadron Exp.
JFY2008 Beams Facility
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11. J-PARC Facility
Linac (KEK/JAEA）
North
3 GeV
Synchrotron
Neutrino Beams
(to Kamioka)
Materials and Life
Experimental
Facility
CY2007 Beams Hadron Exp.
JFY2008 Beams Facility
JFY2009 Beams
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12. J-PARC Hadron Hall
Beam
Dump
K1.8
KL
K1.8BR
K1.1
S-type
30~50 GeV Production
primary beam K1.1BR
target (T1)
C-type
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13. K1.1BR = K0.8 Beam Line Installation
Proton beam
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14. K1.1BR = K0.8 Beam Line Installation
 K1.1BR completed in summer 2010 using the supplementary budget of FY09
 Commissioned in Oct. 2010 by the TREK collaboration
- ESS Length of 2.0m to be increased to 2.5m
- Length Q8-FF of 3.3m to be reduced to 1.5m (remove iron shielding wall)
Q1, Q2
D2
T1 D1
Q3, Q4
IFX,
Proton beam IFY SX1
ESS
Q5, Q6
SX2
K1.1-BR SX1 MS D3
HFOC
Q7 Q8
• FF
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15. The TREK Experimental Apparatus
K+→m Use an upgraded E246 detector
Active Polarimeter
( Japan )
New Fibre Target
( Canada )
C0,C1 GEM
( USA )
CsI(Tl) readout ( Russia )
PT is measured as the azimuthal asymmetry Ae+ of the m+ decay positrons
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16. The Stopped Beam Method K+→m
Side view of the TREK setup
Experimental method bwd -  fwd - 
0 (2) detection EM Calorimeter
Decay Plane
m+ tracking Target + 5 Chambers
e+ detection Active Muon Polarimeter
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17. The Stopped Beam Method K+→m
Electromagnetic calorimeter
0 detection bwd -  fwd - 
768 CsI(Tl) crystals (250mm in length ea.)
12 “muon holes” @ 90º to allow m+ to enter 12 spectrometer gaps
75% of 4 str
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18. The Stopped Beam Method K+→m
Tracking system
Charged particle tracking bwd -  fwd - 
5 Chambers :
1 cylindrical GEM chamber (C0)
1 planar GEM chamber (C1) + Active Target !
3 planar MWPCs (C2, C3, C4)
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19. The Stopped Beam Method K+→m
e+
Active muon polarimeter
m+ polarization measurement bwd -  fwd - 
Active Muon Polarimeter
Muon stopper : 33 plates (Al, Mg or other light metal alloy)
Plate thickness : ~ 2mm
Plate gap ~ 8mm
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20. The Stopped Beam Method K+→m
Double ratio experiment
AT = (Afwd - Abwd ) / 2
Ncw - Nccw
Afwd(bwd) =
Ncw + Nccw
PT = AT / {<cosT>}
 : analyzing power
<cosT> : attenuation factor
Im = PT / KF : physics parameter
KF : kinematic factor
bwd -  fwd - 
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21. The Stopped Beam Method K+→m
Double ratio experiment
AT = (Afwd - Abwd ) / 2
Ncw - Nccw
Afwd(bwd) =
Ncw + Nccw
PT = AT / {<cosT>}
 : analyzing power
<cosT> : attenuation factor
Im = PT / KF : physics parameter
KF : kinematic factor
Current limit from KEK--E246 bwd -  fwd - 
PT = - 0.0017 ± 0.0023(stat) ± 0.0011(syst) |PT | < 0.005 (90% CL)
Im= - 0.0053 ± 0.0071(stat) ± 0.0036(syst) |Im| < 0.016 (90% CL)
M.Abe et al., Phys. Rev. D 73, 072005 (2006)
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22. TREK/E06 Tracking Upgrade
GEM technology --
In collaboration with
Jefferson Lab,
Hampton U. and MIT
70 µm holes
140 µm spacing
 Planar GEMs (C1)
between CsI and C2
 Cylindrical GEM (C0)
as replacement for old C1
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23. The C0 Cylindrical GEM for TREK
300 mm
160 mm
140 mm
• Vertex tracking near target,  < 0.1 mm
• Very high rate capability > 1 kHz/mm2
• Radiation-hardness >> 107 particles/mm2
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24. R&D(1) – APD Readout for CsI(Tl)
• Improve the timing characteristics of
CsI(Tl) by replacing PIN diode with APD
• Pulse shaping and pile-up analysis
C1 GEM
One-module energy One-module timing
new requirement too slow
• Both 1 and 9 module tests have been performed using an e+ beam at Tohoku
Univ. to check the energy resolution and high-rate performance of APD readout
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25. R&D(2) – Active Muon Polarimeter
Top View
e+
μ+
μ+
 Full angular acceptance for positrons – 10x higher than in E-246
 Determination of decay vertex – background-free measurement
 Measurement of e+ angle and approx. energy – higher analyzing power
 Improved field alignment – suppressed systematic error
 Full-size prototype tested at TRIUMF in Nov. 2009
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26. R&D(3) – Active Scintillating Fiber Target
Light Guide:
Kuraray Y11 WLS Fibre (1400 mm)
3x3 mm2
356 fibres
Readout:
SiPMT (Hamamatsu MMPC)
1x1 mm2 / 400 px
Gain 7.5x105
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27. Upgrade Timeline
 Target:
 Finer segmentation of TGT scintillating fibres
Readout: MPPC (SiPMT) Hamamatsu
 Particle ID:
 Aerogel Cherenkov surrounding target, TOF LFU
 Charged particle tracking: 30 kW
 Add new element C1 between CsI(Tl) and C2 ~2013
 Add cylindrical GEM (C0) (remove aerogel)
TREK
 0 (1&2 photon) detection:
270 kW
 New, faster readout of CsI(Tl): APD, MAPD
 Wave form analysis using FADCs
>100 kW
~2014
 Muon polarimeter :
 Active polarimeter with increased acceptance
 New muon holding field magnet with a parallel field
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28. Summary
 TREK at J-PARC is gaining momentum
 “K1.1BR” secondary beamline has been commissioned
 Measurement of the T-violating transverse muon
polarization in Kμ3 decay (~2014)
- Large potential for the discovery of New Physics
- Upgrade of existing experimental setup of KEK E-246
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29. The TREK Collaboration
http://trek.kek.jp
CANADA RUSSIA
University of Saskatchewan Russian Academy of Sciences (RAS)
Department of Physics and Engineering Institute for Nuclear Research (INR)
University of British Columbia
Department of Physics and Astronomy
TRIUMF
Universite de Montreal
JAPAN
Osaka University
Laboratoire de Physique Nucleaire
Department of Physics
University of Manitoba
National Defense Academy
Department of Physics
Department of Applied Physics
Tohoku University
USA Research Center for Electron Photon Science
High Energy Accel. Research Org. (KEK)
Massachusetts Inst. of Technology (MIT)
Institute of Particle and Nuclear Studies
University of South Carolina
Institute of Material Structure Science
Department of Physics and Astronomy
Accelerator Laboratory
Iowa State University
Kyoto University,
College of Liberal Arts & Sciences
Department of Physics
Hampton University
Tokyo Institute of Technology (TiTech)
Department of Physics
Department of Physics
Jefferson Laboratory
VIETNAM
University of Natural Sciences
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30. The TREK Collaboration
http://trek.kek.jp
CANADA RUSSIA
University of Saskatchewan Russian Academy of Sciences (RAS)
Department of Physics and Engineering Institute for Nuclear Research (INR)
University of British Columbia
Department of Physics and Astronomy
TRIUMF
Universite de Montreal
JAPAN
Osaka University
Laboratoire de Physique Nucleaire
Department of Physics
University of Manitoba
National Defense Academy
Department of Physics
Department of Applied Physics
Tohoku University
USA Research Center for Electron Photon Science
High Energy Accel. Research Org. (KEK)
Massachusetts Inst. of Technology (MIT)
Institute of Particle and Nuclear Studies
University of South Carolina
Institute of Material Structure Science
Department of Physics and Astronomy
Accelerator Laboratory
Iowa State University
Kyoto University,
College of Liberal Arts & Sciences
Department of Physics
Hampton University
Tokyo Institute of Technology (TiTech)
Department of Physics
Department of Physics
Jefferson Laboratory
VIETNAM
New collaborators are welcome! University of Natural Sciences
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31. Thank You
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32. J-PARC March11 Earthquake Damage
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33. S. Bianchin PANIC 2011 (July 24th – 29th 2011)