results of the koto experiment at j-parcvietnam.in2p3.fr/2014/flavour/wednesdaymorning/nanjo.pdf ·...
TRANSCRIPT
![Page 1: Results of the KOTO experiment at J-PARCvietnam.in2p3.fr/2014/flavour/WednesdayMorning/Nanjo.pdf · Results of the KOTO experiment at J-PARC Flavor Physics Conference July 30th 2014](https://reader033.vdocuments.site/reader033/viewer/2022042621/5f73caccc18d0051557849c2/html5/thumbnails/1.jpg)
Results of the KOTO experiment at J-PARC
Flavor Physics Conference July 30th 2014Hajime NANJO (Kyoto Univ.)
for the KOTO collaboration
Arizona State, Chicago, Chonbuk, Jeju, JINR, KEK, Kyoto, Kyungpook,Michigan, NDA, NTU, Okayama, Osaka, Pusan, Saga, Yamagata
![Page 2: Results of the KOTO experiment at J-PARCvietnam.in2p3.fr/2014/flavour/WednesdayMorning/Nanjo.pdf · Results of the KOTO experiment at J-PARC Flavor Physics Conference July 30th 2014](https://reader033.vdocuments.site/reader033/viewer/2022042621/5f73caccc18d0051557849c2/html5/thumbnails/2.jpg)
Contents
● KOTO took 1st physics run in May 2015.
– Only 100 hours due to the accident in J-PARC Hadron Hall.
● Blind analysis is still on going. We will show the results soon. Not today.
● I will show
– How we understand the detector performance
– Detector/Accelerator plan
– Expected sensitivity toward the future
![Page 3: Results of the KOTO experiment at J-PARCvietnam.in2p3.fr/2014/flavour/WednesdayMorning/Nanjo.pdf · Results of the KOTO experiment at J-PARC Flavor Physics Conference July 30th 2014](https://reader033.vdocuments.site/reader033/viewer/2022042621/5f73caccc18d0051557849c2/html5/thumbnails/3.jpg)
2014/7/30 3
● Rare FCNC process Br(SM)=(2.4±0.4)x10-11
– GIM suppression for u, c
– Hierarchical structure of CKM for t quark
● Small theoretical uncertainty (~2%)
– Short distance (W,Z,t)
– Ke3 hadron matrix element from data
● Direct CP violation
c
u
t
d s b
(Only t contribution for this decay)
Sensitive to new physics which break flavor structure and add new CP-violation
(in the SM)
![Page 4: Results of the KOTO experiment at J-PARCvietnam.in2p3.fr/2014/flavour/WednesdayMorning/Nanjo.pdf · Results of the KOTO experiment at J-PARC Flavor Physics Conference July 30th 2014](https://reader033.vdocuments.site/reader033/viewer/2022042621/5f73caccc18d0051557849c2/html5/thumbnails/4.jpg)
2014/7/30 4
KOTO at J-PARC
High intensity proton beam (30GeV)Slow extraction24kW(2013) → 100kW
Primary target (Au)
KOTO detector
KL beam lineLong (20m)Charged particle sweeping magnetNarrow collimator
Long lived neutral particle → n,γ,KL30 GeV proton
![Page 5: Results of the KOTO experiment at J-PARCvietnam.in2p3.fr/2014/flavour/WednesdayMorning/Nanjo.pdf · Results of the KOTO experiment at J-PARC Flavor Physics Conference July 30th 2014](https://reader033.vdocuments.site/reader033/viewer/2022042621/5f73caccc18d0051557849c2/html5/thumbnails/5.jpg)
2014/7/30 5
KOTO detector“Two γ from π0 and nothing else” CsI calorimeter and Hermetic veto
π0 with high PT discriminate K
L→2γ
Other K decays have charged or γ more than two
“Veto almost everything” experiment
![Page 6: Results of the KOTO experiment at J-PARCvietnam.in2p3.fr/2014/flavour/WednesdayMorning/Nanjo.pdf · Results of the KOTO experiment at J-PARC Flavor Physics Conference July 30th 2014](https://reader033.vdocuments.site/reader033/viewer/2022042621/5f73caccc18d0051557849c2/html5/thumbnails/6.jpg)
2014/7/30 6
Calorimeter performance
● 6 cluster sample
– π0 reconstruction
– Calorimeter resolution● Tuned MC:
2716 Undoped CsI50 cm in length2.5x2.5 or 5x5 cm2
1.9m
![Page 7: Results of the KOTO experiment at J-PARCvietnam.in2p3.fr/2014/flavour/WednesdayMorning/Nanjo.pdf · Results of the KOTO experiment at J-PARC Flavor Physics Conference July 30th 2014](https://reader033.vdocuments.site/reader033/viewer/2022042621/5f73caccc18d0051557849c2/html5/thumbnails/7.jpg)
2014/7/30 7
Veto performance (1)
● Four cluster sample
– Charged veto (CV) and Barrel photon veto (MB)
– We understood the veto performance as expected.
Apply MB vetoCV veto
MB
CV
![Page 8: Results of the KOTO experiment at J-PARCvietnam.in2p3.fr/2014/flavour/WednesdayMorning/Nanjo.pdf · Results of the KOTO experiment at J-PARC Flavor Physics Conference July 30th 2014](https://reader033.vdocuments.site/reader033/viewer/2022042621/5f73caccc18d0051557849c2/html5/thumbnails/8.jpg)
2014/7/30 8
Veto performance (2)● Special study with a tracking system in 2012.
– Single charged particle ● Track with drift chambers upstream of CV● Require calorimeter hit downstream of CV
– Ineffciency < 2x10-5 for single layer ● Two layers of 3mm thick plastic scintillator with WLS fber readout
● High light yield with MPPC (3x3mm2)
e-+
10-3 is required to reduce Ke3 background
Energy deposit in CV
100keV (~19 p.e.)
![Page 9: Results of the KOTO experiment at J-PARCvietnam.in2p3.fr/2014/flavour/WednesdayMorning/Nanjo.pdf · Results of the KOTO experiment at J-PARC Flavor Physics Conference July 30th 2014](https://reader033.vdocuments.site/reader033/viewer/2022042621/5f73caccc18d0051557849c2/html5/thumbnails/9.jpg)
2014/7/30 9
PT reconstruction
● Two cluster sample → Reconstruct KL assuming
– KL mass
– Vertex on Z axis
● Understanding of the collimated beam and gamma measurement with the calorimeter.
● Veto detector performance is also as expected.2013.1(loose veto) 2013.5
for KL → 2 gamma
![Page 10: Results of the KOTO experiment at J-PARCvietnam.in2p3.fr/2014/flavour/WednesdayMorning/Nanjo.pdf · Results of the KOTO experiment at J-PARC Flavor Physics Conference July 30th 2014](https://reader033.vdocuments.site/reader033/viewer/2022042621/5f73caccc18d0051557849c2/html5/thumbnails/10.jpg)
2014/7/30 10
Detector staging / upgrading● In-beam charged veto (BHCV)
– 3mm-thick plastic scintillator → ~3mm-thick wire chamber (2014).
– Reduce accidental hits in-beam gamma and neutron● Now 6MHz hit rate (maximum in KOTO)
● In-beam photon veto (BHPV)
– Lead-aerogel sandwich Cerenkov counter. (insensitive to neutron)
– Increase the depth along the beam axis to reduce punch-through ineffciency● Now 4X0 (4% in effciency) → 5.4X0(1.5% in effciency) (2014) → 9X0 for the fnal design
● Barrel photon veto (MB) (Summer 2015)
– Lead-plastic scintillator sandwich
– Increase the depth to reduce punch-though ineffciency● Now 13.5X0 → 18.5 X0
![Page 11: Results of the KOTO experiment at J-PARCvietnam.in2p3.fr/2014/flavour/WednesdayMorning/Nanjo.pdf · Results of the KOTO experiment at J-PARC Flavor Physics Conference July 30th 2014](https://reader033.vdocuments.site/reader033/viewer/2022042621/5f73caccc18d0051557849c2/html5/thumbnails/11.jpg)
2014/7/30 11
J-PARC Slow Extraction
● Power in 2013 : 24kW → 100kW planed in 2017
● Duty : 2sec/6sec
● Duty in spill : ½
– High accidental rate (x2)
→ trying to reduce
Ideal case
As of 2014
Time (sec)
Extracted Beam
![Page 12: Results of the KOTO experiment at J-PARCvietnam.in2p3.fr/2014/flavour/WednesdayMorning/Nanjo.pdf · Results of the KOTO experiment at J-PARC Flavor Physics Conference July 30th 2014](https://reader033.vdocuments.site/reader033/viewer/2022042621/5f73caccc18d0051557849c2/html5/thumbnails/12.jpg)
2014/7/30 12
JFY2018
JFY2014
2013.51st physics runexpectation
Direct limit 2.6x10-8 (KEK E391a)
Indirect limit 1.5x10-9 (Grossman-Nir)
SM sensitivity 2.4x10-11
10-8
10-9
10-10
10-11
New Physics?
O(100) SM events or more in KOTO Step-2 plan
Now and Future
![Page 13: Results of the KOTO experiment at J-PARCvietnam.in2p3.fr/2014/flavour/WednesdayMorning/Nanjo.pdf · Results of the KOTO experiment at J-PARC Flavor Physics Conference July 30th 2014](https://reader033.vdocuments.site/reader033/viewer/2022042621/5f73caccc18d0051557849c2/html5/thumbnails/13.jpg)
2014/7/30 13
Summary● Blind analysis for 1st Physics run → coming soon
– Calorimeter and veto performances are well understood.
● Next run will be started in early 2015
→ beyond the Grossman-Nir bound.
● Detector staging/upgrade is on going.
● Explore large new physics area with accelerator efforts.
2018
2015
3-sigma discovery area
![Page 14: Results of the KOTO experiment at J-PARCvietnam.in2p3.fr/2014/flavour/WednesdayMorning/Nanjo.pdf · Results of the KOTO experiment at J-PARC Flavor Physics Conference July 30th 2014](https://reader033.vdocuments.site/reader033/viewer/2022042621/5f73caccc18d0051557849c2/html5/thumbnails/14.jpg)
2014/7/30 14
backup
![Page 15: Results of the KOTO experiment at J-PARCvietnam.in2p3.fr/2014/flavour/WednesdayMorning/Nanjo.pdf · Results of the KOTO experiment at J-PARC Flavor Physics Conference July 30th 2014](https://reader033.vdocuments.site/reader033/viewer/2022042621/5f73caccc18d0051557849c2/html5/thumbnails/15.jpg)
2014/7/30 15
![Page 16: Results of the KOTO experiment at J-PARCvietnam.in2p3.fr/2014/flavour/WednesdayMorning/Nanjo.pdf · Results of the KOTO experiment at J-PARC Flavor Physics Conference July 30th 2014](https://reader033.vdocuments.site/reader033/viewer/2022042621/5f73caccc18d0051557849c2/html5/thumbnails/16.jpg)
2014/7/30 16
![Page 17: Results of the KOTO experiment at J-PARCvietnam.in2p3.fr/2014/flavour/WednesdayMorning/Nanjo.pdf · Results of the KOTO experiment at J-PARC Flavor Physics Conference July 30th 2014](https://reader033.vdocuments.site/reader033/viewer/2022042621/5f73caccc18d0051557849c2/html5/thumbnails/17.jpg)
17
KOTO2# of KL,neutron v.s. Extraction angle
neutron
KL
KOTO2 KOTO1
● Extraction angle : 5 degree
● Just behind dump
– ~50m from target
● Long decay volume and large calorimeter
● 100 SM events → 10% measurement of BR
Hadron Hall Extension
![Page 18: Results of the KOTO experiment at J-PARCvietnam.in2p3.fr/2014/flavour/WednesdayMorning/Nanjo.pdf · Results of the KOTO experiment at J-PARC Flavor Physics Conference July 30th 2014](https://reader033.vdocuments.site/reader033/viewer/2022042621/5f73caccc18d0051557849c2/html5/thumbnails/18.jpg)
2014/7/30 18
● CP violation in quark sector and Baryogenesis
● Why Minimum Flavor Violation?
● New physics models for KOTO and LHC limitation
![Page 19: Results of the KOTO experiment at J-PARCvietnam.in2p3.fr/2014/flavour/WednesdayMorning/Nanjo.pdf · Results of the KOTO experiment at J-PARC Flavor Physics Conference July 30th 2014](https://reader033.vdocuments.site/reader033/viewer/2022042621/5f73caccc18d0051557849c2/html5/thumbnails/19.jpg)
2014/7/30 19
● E391a fnal result with ~100 days run time
– Br < 2.6x10-8 (90% CL)