1 / 31

The new K L  p 0 nn experiment (KOTO) at J-PARC

The new K L  p 0 nn experiment (KOTO) at J-PARC. Hiroaki Watanabe for the J-PARC E14 KOTO collaboration KEK, IPNS. J-PARC E14 KOTO Collaboration. KOTO: K 0 at TO kai. Univ. of Michigan, Ann Arbor National Defense Academy Osaka Univ. Pusan National Univ. Saga Univ. Univ. of Seoul.

pembroke
Download Presentation

The new K L  p 0 nn experiment (KOTO) at J-PARC

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The new KL p0nn experiment (KOTO) at J-PARC Hiroaki Watanabe fortheJ-PARCE14KOTOcollaborationKEK, IPNS

  2. J-PARC E14 KOTOCollaboration KOTO:K0atTOkai. • Univ. of Michigan, Ann Arbor • National Defense Academy • Osaka Univ. • Pusan National Univ. • Saga Univ. • Univ.ofSeoul. • National Taiwan Univ. • Yamagata Univ. • Arizona State Univ. • ChejuNationalUniv. • ChonbukNationalUniv. • Univ. of Chicago • JointInstituteforNuclearResearch(JINR) • KEK • Kyoto Univ. • KyungpookNationalUniv. 16 Institutes from 5 countries.62collaborators.

  3. Vtd Measurement of Br(KL p0nn) Amplitude of CP-violation in Quark Sector. • The clean process : • 1～2 % theoretical uncertainty • Sensitive to New Physics.

  4. F. Mescia and C. Smith updated in June, 2010.

  5. Strategy • Step by Step approach. • KEK-E391a (previous experiment) • Establishmentof • experimentalmethod. • J-PARC Step-1 (E14 KOTO)  First observation. Search for enhancement by New Physics. • J-PARC Step-2  > 100 events E391a-final

  6. n g KL p0 g Proton n Experimental Method KL p0nn Calorimeter (CsI crystals) Surrounding with veto counters 2g + Nothing KL collimators 1 . Hermitic veto with high detection efficiency: To count number of photons. - KLp0p0 (4g ) is most serious background by missing 2 g. 2. Pencil Beam : to obtain kinematical constraints.  KL decay on Z-axis. - reconstruction of decay vertex(Zvtx) and transverse momentum(PT) of p0.

  7. Previous experiment: Sensitivity in KEK-E391a PRD 74,051105(R) (2006) PRL 100,201802 (2008) • Number of KL decay • Signal Acceptance • Single event sensitivity PRD 81,072004 (2010) Br(KL p0nn) < 2.6X10-8

  8. Previous experiment: Backgrounds in KEK-E391a • Halo neutron + detector material • p0 + X ( or  h + X) *More detail can be seen in Poster session.

  9. J-PARC KOTO : Sensitivity and background • Intense proton beam at J-PARC: • New accelerator . • Longer physics run. • New KL beamline: 16o extraction. • Softer KL beam. Decay prob. • n/KL ratio: 456.5. • Softer neutron beam: x0.13 due to reduction of production probability. • Optimized optics to suppress halo neutrons: Halo-n/KL =0.07%, 1/240 of E391a. • Upgraded detector and electronics: • Longer and finer segmented CsI crystals ( loaned from KTeV at Fermilab). • Improved veto counters. • New pipeline-readout flash ADC for high rate. • x3.6 acceptance is expected than that of E391a. • 2x10-6 reduction of halo-neutron background by detector upgrades. • 3 p0nn events are expected. • 2.5 background events are expected. (p0p0 backgrounds are dominated. Halo-neutron event is negligible.)

  10. 3 GeV Synchrotron J-PARC (Japan Proton Accelerator Research Complex) Linac 30 GeV Synchrotron 2x1014 protons/spill, 1spill=3.3sec. (design value). Hadron Hall

  11. Parameters of beam • Item J-PARC E14 KOTO KEK-E391a • Primary proton energy 30 GeV 12 GeV • Proton intensity(/spill) 2x1014 2.5x1012 • Spill-length/repetition 0.7s / 3.3s 2s / 4s • Production target Common “T1” Pt rod • Extraction angle 16 deg. 4 deg. • KL yield(/spill) 8.1x106 3.3x105 • Average PKL2.1 GeV/c 2.6 GeV/c • n/KLratio6.545 Momentumdist.ofNeutron Momentum dist. of KL. p

  12. Layoutofthe KL beamlineatJ-PARC 30GeVProton T1target Photonabsorber Beamplug 1stcollimator (4m-long) 2ndcollimator (4.5m+0.5m-long) KOTOdetector Sweepingmagnet

  13. Collimator optimization. Key:Halo neutron produced by multiple scattering at inner surfaces of collimators. 1. Primary collimation to form beam core shape and size. 2. Trimming collimation to suppress scattered neutron at upstream hot regions. ･　Haloneutron/KL:0.07%(E14-request:<0.13%) (1/240 reduction than E391a)

  14. Detector Upgrade. J-PARC KOTO(loaned from KTeV),50cm-long 27X0 KEK-E391a, 30cm-long (16X0) Reconstruction-vertex 4x10-5 reduction of halo-n B.G. γ γ Lead/plastic-scintillator  segmented CsI’s. (1/20 reduction of halo-neutron B.G.)

  15. Assuming 12 months of physics run=1.8x1021 protons on target • 3 p0nn events are expected • 2.5 background events are expected. • S/B = 1.2 • B.G. source No. of B.G events. • Other KL decay • KLp0p01.8 • KLp+p-p0 0.4 • KLp-e+n 0.005 • KLgg negligible • KLp0p0p0 negligible • Neutron Interaction • With Residual gas 0.04 • At the CC02 0.01 • At the C.V. negligible • Accidental coin. 0.10 MC: KLp0nn

  16. Preparation status • Beamline construction in 2009. • CsI-calorimeter construction in 2010. • Completion of whole detector in 2011. • First Physics Run in 2012. • Reaching GN-limit, 1.5x10-9.

  17. Photo in July, 2009 2nd collimator (4.5+0.5m) Beam plug 1st collimator （4m-long） Dipole magnet beam

  18. Beam survey: Nov. 2009～Feb. 2010. 6×1011 ～2×1012protons/spill(1spill=6sec) Exit of KL beamline KL1: KLp+p-p0 measurement using hodoscopes and mini-calorimeter Upstream Beam profile monitor KL2: KLp+p-by spectrometer Core Neutron/gamma meas. Downstream

  19. Measurement of KL Yield by detecting KLp+p-p0 • No data for 16o extraction at 30GeV. • Big differences betw. M.C. simulations. Reconstructed Mass. Reconstructed KL Momentum • 1905 events were observed. • 1.83x107 KL’s/2x1014 p.o.t. • (*preliminary number) • It corresponds to • Proposal-yield x 2.3 • (*MR DCCT normalization) *More detail can be seen in Poster session.

  20. Beam profile PWO, CsI crystals Overall beam shape is well reproduced by M.C. simulation.

  21. Calorimeter construction Vacuum chamber PMT holder installation Stacking of CsI crystals

  22. Summary and prospect • J-PARC KOTO aims at First Observation(～3 events) of KLp0nnusing: • High intensity proton beam at J-PARC, • New KL beamline, • Upgraded detector + new fast electronics. • Beamline construction and survey was completed in 2009. • x2.3 KL yield compared to that of the proposal has been observed. • Beam shape is well reproduced by M.C. simulation. • Stacking of CsI calorimeter has been started. • Engineering run with CsI’s and new readout system will be started in Oct.,2010. • In 2011, whole detector system will be completed. • In 2012, first physics run will be started. reaching the Grossman-Nir limit, 1.5x10-9.

  23. backup

  24. J-PARC at Tokai mura

  25. July, 2009 Pacific Ocean

  26. Plan View: Hadron Experimental Hall Beam Dump （Movable on the Rail) Baryons in Nuclei K1.8 Mesons in Nuclei Rare Decay K1.8BR KL • Production • target (T1) K1.1 T1 target K1.1BR Mesons mass/ Time reversal 30GeV Primary Beam High Momentum Beam Line

  27. ○ 54mm-thick pure-Nickel. It divided in to 5 disks 21.7, 11.2, 8.3, 6.9, 5.9 ○Beam Energy: up to 50 GeV. ○Beam Size : sX,sY:1.3mm ○　Target is cooled by water in 1 atm. T1 common target Beam

  28. beam beam July 11 August 7 beam

  29. Calorimeter preparation Beam test of CsI’s and electronics • 144 Channels were tested by positron beam • Performance test for complete set of read-out • CW-base, 125MHz FADC, Trigger board • Figure out problems, confirm no problem for stacking Energy Resolution (%, s/E) Positron Energy(MeV)

  30. Proposed Detector Upgrade( cont’d) Acceptance loss by BHPV due to accidental hit : 30~40 %(E391a 2E+12ppp)  2 % (E14, 2E+14ppp) 99.9% Lead / Aerogel Cerenkov radiator

  31. CsI Read-out

More Related