Upload
caraf
View
25
Download
1
Embed Size (px)
DESCRIPTION
Kyoto University H. Nanjo for E391a and K O TO collaboration. Collaboration. KEK-PS E391a The first dedicated experiment for K L p 0 nn . J-PARC E14 to measure Br(K L p 0 nn ) at J-PARC K O TO (K0 at Tokai) Japan-USA-Russia-Taiwan-Korea 5 countries and 15 institutes. - PowerPoint PPT Presentation
Citation preview
New Developments of Flavor Physics 20091
Kyoto University
H. Nanjo
for E391a and KOTO collaboration
TOK and E391a
Experiment K O
0L
New Developments of Flavor Physics 2009
• KEK-PS E391a– The first dedicated experiment for KL .
• J-PARC E14• to measure Br(KL ) at J-PARC
– KOTO (K0 at Tokai)• Japan-USA-Russia-Taiwan-Korea
– 5 countries and 15 institutes.
• Based on E391a collaboration.• New members are joining.
• We aim to discover KL
with the similar method
used in the E391a.
Collaboration
2
KEKKyotoNDAOsakaSagaYamagataArizona StateChicagoMichiganJINRNational TaiwanPusan NationalSeoulCheonBuk NationalJeju National
New Developments of Flavor Physics 2009
Br)in accuracy (10%
K from constraint 0L
K
K L0
• Flavor Physics– Direct CP violation.
– Br(KL0)
• :Complex phase in CKM (Height of unitary triangle)
• Beyond the SM– Rare FCNC process (highly suppressed in SM).
• Br(KL0)=(2.8 0.4) 10-11
– Very Sensitive to new physics(TeV-Scale Physics).
• Small theoretical uncertainty– Short distance physics (>99% due to t quark) 2% uncertainty in (Br ) Golden mode.
Motivation
3
New Developments of Flavor Physics 2009
KOTO Physics Run 20112014
E391a
New Physics
Status and Room for New Physics
4
1015.105.1 1073.1
Br
)%90(1046.1 9 CLBr
)%90(107.6 8 CLBr
Chance to reach TeV-scale New Physics using Kaon Next-Generation World-Wide Kaon Physics
– KEK-PS E391 Run2 – Run3 analysis KOTO
– Grossman-Nir bound– model independent (can be violated if LFV)
– indirect limit from K+ BNL E797/E949
CERN NA62 European Rare-decays Experiments with Kaons , FNAL Project-X
New Developments of Flavor Physics 2009
Concept of Experiment• KL beam (proton target)
– neutral beam line » Long beam line Kill particles with shorter lifetime
» Charged particle sweeping magnet.
» Pb photon absorber reduce beam photons
» Collimator shaping (source of beam halo)
– Core : KL, photon, neutron
– Halo : neutron scattering on the surface of collimator
• Detector– () and nothing
• Photon calorimeter and hermetic vetos
5
New Developments of Flavor Physics 2009
Concept of Experiment• How to make KL beam?
– Proton beam Target KL
6
proton
target
KL
New Developments of Flavor Physics 2009
Concept of Experiment• How to make KL beam?
– Proton beam Target KL
» Charged particles
» neutral short-lived particles
» photon
» neutron
7
proton
target
photon
neutroncharged particle
KLShort Lived
New Developments of Flavor Physics 2009
Concept of Experiment• How to make KL beam?
– Proton beam Target KLShaping Collimator» Charged particles
» neutral short-lived particles
» photon
» neutron
8
proton
target
photon
neutroncharged particle
collimator
KLShort Lived
New Developments of Flavor Physics 2009
Concept of Experiment• How to make KL beam?
– Proton beam Target KLShaping Collimator» Charged particles sweeping magnet
» neutral short-lived particles long beam line
» photon Pb absorber (kill but pass KL)
» neutron
9
B
proton
target
photon
neutroncharged particle
collimator
PbKLShort Lived
c KL 15000mm 87mm 79mmKS 27mm
New Developments of Flavor Physics 2009
Concept of Experiment• How to make KL beam?
– Proton beam Target KLShaping Collimator– core : neutron, photon
– halo : neutron (scattering at Pb /on the surface of collimator)
10
B
proton
target
neutron
collimator
PbKL
halo neutron
core photon, neutron
New Developments of Flavor Physics 2009
Concept of Experiment• How to detect KL0?
– () and nothing• Photon calorimeter
11
B
proton
target
collimator
PbKL
0
halo neutron
core photon, neutron
New Developments of Flavor Physics 2009
Concept of Experiment• How to detect KL0?
– () and nothing• Photon calorimeter and hermetic vetos
– for photons
12
B
proton
target
collimator
PbKL
0
halo neutron
core photon, neutron
0
New Developments of Flavor Physics 2009
Concept of Experiment• How to detect KL0?
– () and nothing• Photon calorimeter and hermetic vetos
– for photons and charged particles
13
B
proton
target
collimator
PbKL
0
halo neutron
core photon, neutron-
+
New Developments of Flavor Physics 2009
Concept of Experiment• How to detect KL0?
– () and nothing• Photon calorimeter and hermetic vetos
– for photons and charged particles
• Beam hole veto under huge core /n flux Weaker veto.
14
B
proton
target
collimator
PbKL
0
halo neutron
core photon, neutron
New Developments of Flavor Physics 2009
Concept of Experiment• How to detect KL0?
– () and nothing• Photon calorimeter and hermetic vetos
– for photons and charged particles
• Beam hole veto under huge core /n flux Weaker veto.
• Make beam hole small!
Pencil Beam
15
B
proton
target
collimator
PbKL
0
halo neutron
core photon, neutron
New Developments of Flavor Physics 2009
Concept of Experiment• How to detect KL0?
– () and nothing• Photon calorimeter and hermetic vetos
– for photons and charged particles
• Beam hole veto under huge core /n flux Weaker veto.
• Make beam hole small!
16
B
proton
target
collimator
PbKL
0
halo neutron
core photon, neutronPencil Beam
New Developments of Flavor Physics 2009
Concept of Experiment
17
proton
target
PbKL
0
halo neutron
core photon, neutron
• How to reconstruct KL0?
– in Calorimeter and nothing– Energy and Position.
– Reconstruct – assuming KL vertex in the beam line thanks to the pencil beam.
– Decide Zvtx with 0 invariant mass .
0 full reconstruction
New Developments of Flavor Physics 2009
Concept of Experiment
18
proton
target
PbKL
0
halo neutron
core photon, neutron
• How to reconstruct KL0?
– in Calorimeter and nothing– Energy and Position.
– Reconstruct – assuming KL vertex in the beam line thanks to the pencil beam.
– Decide Zvtx with 0 invariant mass .
0 full reconstruction
2021 )cos1(2 mEE
E1
E2
New Developments of Flavor Physics 2009
Concept of Experiment• Kinematics of KL
– 0 PT-Zvtx Plane (Kinematics and Fiducial)– Higher PT distribution of 0
– Max 231 MeV/c (V-A theory)
– Kaon-orign background• Veto and Kinematics
19ZZKL→2γKL→2γ
PTPT
KL→2π0KL→2π0
signal regionsignal region
KL→π+π-π0KL→π+π-π00
00 (even)+-0
Signal Region
New Developments of Flavor Physics 2009
Concept of Experiment
20
B
proton
target
collimator
Pb 0 /0 production
halo neutron
2021 )cos1(2 mEE
• Halo neutron background– halo neutron interact with detector component
create 0 /0 decay to 2 – Vertex position shift due to
• Energy mis-measurement– photonuclear, neutron-contami
• 0 mass
New Developments of Flavor Physics 2009
• halo-n background in PT-Zvtx Plane
– Contamination into the signal box
• Point– Suppress halo-n– Lower halo-n momentum– Reduce material– Place it far from
signal region– Veto at 0 production
Concept of Experiment
21
ZZhalo-n CV-halo-n CV-
PTPT
halo-n CC02 π0halo-n CC02 π0
signal regionsignal regionhalo-n CV-0halo-n CV-0
2021 )cos1(2 mEE
New Developments of Flavor Physics 2009
KL
E391a Experiment• KL production with KEK 12GeV PS
– 2 x 1012 protons on target (POT) per 2sec spill, 4sec cycle– production angle: 4°, KL peak momentum 2GeV/c, n/KL ratio: ~40
• 0 and nothing.– Pure CsI Calorimeter – Hermetic Vetos
• Physics runs– Run I: February to July of 2004
• “Express” analysis with 10% data published in PRD (2006)
– Run II: February to April of 2005 (~ 32 days without break)
• published in PRL(2007)
– Run III: October - December of 2005• Analysis Expect to be finished in 2009
22
New Developments of Flavor Physics 2009
E391 Detector• a
23
• Decay region– High vacuum: 10-5 Pa
• to suppress the backgroundfrom interactions w/ residual gas
• Detector components– Set in the vacuum: 0.1 Pa
• separating the decay regionfrom the detector regionwith “membrane”: 0.2mmt film
New Developments of Flavor Physics 2009
E391a Status• KL
– Run2 Published Phys.Rev.Lett.100,201802(2008)
• No event observed. (BG estimate 0.41)
– Run3 Analysis• ~ 2 times higher sensitivity expect to be finished in 2009
– 3 order to SM sensitivity KOTO
• KL X (Xlight pseudoscalar particle X
– Published with Run2 data Phys.Rev.Lett.102,051802(2009)
• KL X (X– Analysis in final stage with Run3 data.
24
)%90(107.6 8 CLBr
2x
7 214.3MeV/cmfor )%90(104.2 CLBr
New Developments of Flavor Physics 200925
Strategy from E391a to KOTO• High intensity beam
• New beam line (halo-n surpress)
• Detector upgrade (background)
MR(50GeV PS) perimeter~1.6km30 GeV for slow ext.21014 ppp 0.3MW0.7s spill/3.3s repe.
T1 Ni Target
E391 det. at 16 deg line
proton
Exp Hall
20m neutral beamline
New Developments of Flavor Physics 200926
High intensity beam• Flux x RunTime x Acceptance ~2.8 SM
eventKOTO E391a (Run2)
Proton energy 30 GeV 12 GeV
Proton intensity 2e14 2.5e12
Spill/cycle 0.7/3.3sec 2/4sec
Extraction Angle
16 deg 4 deg
Solid Angle 9Str 12.6Str
KL yield/spill 7.1e13 2.4e11 x30 /sec
Run Time 3 s.m. years =12 months.
1 month x10
Decay Prob. 4% 2% x 2
Acceptance 3.6%* 0.67% x5
KOTO
E391a
*without Back splash loss
New Developments of Flavor Physics 2009
New Beamline
27
Jan/2009
CollimatorFabrication
We fixed the beamline design and fabrication is on-going.
New Developments of Flavor Physics 2009
halo-n surpression• E391 : core tail : 10-3 level
• KOTO : : 10-4 level– softer neutron momentum.– beamline design
Next talk by Shimogawa.
28
New Developments of Flavor Physics 200929
Detector UpgradeNCC
Increase Veto PerformanceReduce halo-n affectionCope with high rate
• NCC : move to upstream, full active pure-CsI, WLS fiber readout. – To reduce halo neutron BG and monitor halo-n itself in stew.
• CsI 7730cm2.52.550cm– Reduce inefficiency, improve energy resolution, discrimination of fusion– CW base with amp. to reduce heat and increase gain.
• CV : 2-layer design Scintillator + WLS fiber + MPPC (light, space, cost)• BHPV : Pb converter + Aerogel Cerenkov radiator + winstone cone light collection.
• (single rate@E391 is ~1MHz ~40MHz @J-PARC impossible totally different.) • MB : increase the thickness To reduce the inefficiency
New Developments of Flavor Physics 200930
New Developments of Flavor Physics 200931
New Developments of Flavor Physics 200932
New Developments of Flavor Physics 200933
New Developments of Flavor Physics 200934
New Developments of Flavor Physics 200935
New Developments of Flavor Physics 200936
Summary and prospects• KOTO experiment
to measure Br(KL )• Neutral beamline design is fixed and
fabrication is on-going and delivery and construction in this FY.
• Beamline survey in ~Oct. 2009 with the BL.• Detector upgrade is being designed and
prototype is made and tested toward Engineering run in 2010 and Physics run in 2011.