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ORKA : The Golden Kaon Experiment

ORKA : The Golden Kaon Experiment . Elizabeth Worcester (BNL) for the ORKA collaboration May 1, 2013. Photo: Life of Sea blogspot. ORKA: The Golden Kaon Experiment. Precision measurement of K +  p + nn BR with ~1000 expected events at FNAL MI

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ORKA : The Golden Kaon Experiment

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  1. ORKA: The Golden Kaon Experiment Elizabeth Worcester (BNL) for the ORKA collaboration May 1, 2013 Photo: Life of Sea blogspot

  2. ORKA: The Golden Kaon Experiment • Precision measurement of K+p+nnBR with ~1000 expected events at FNAL MI • Expected BR uncertainty matches Standard Model uncertainty • Sensitivity to new physics at and beyond LHC mass scale • Builds on successful previous experiments • BNL E787/E949 • 7 candidate events already observed ETW: Kaon13, Ann Arbor, MI

  3. Motivation • Flavor problem: • We expect new physics at the TeV scale . . . • Why don’t we see this new physics affecting the flavor physics we study today? • If (BSM) new physics found in LHC searches: • Precision flavor-physics experiments needed to explore flavor- and CP-violating couplings • If no (BSM) new physics found in LHC searches: • Precision flavor-physics experiments needed to search for new physics beyond the reach of direct searches through virtual effects ETW: Kaon13, Ann Arbor, MI

  4. K+p+nn in the Standard Model • Kpnn are the most precisely predicted FCNC decays involving quarks • A single effective operator: • Dominated by top quark • Hadronic matrix element shared with K+p0e+ne • Dominant uncertainty from CKM matrix elements (expect prediction to improve to ~5%) ETW: Kaon13, Ann Arbor, MI

  5. Sensitivity to New Physics arXiv:1211.1896 mZ’ = 5-30 TeV SM arXiv1012.3893 Haisch, 2012 ETW: Kaon13, Ann Arbor, MI Bauer, et. al, 2009 Buras, et. al, 2005

  6. Sensitivity to New Physics arXiv:1211.1896 mZ’ = 5-30 TeV SM Prediction and measurement at 5% level allows 5s detection of deviation from the Standard Model as small as 30%. K+p+nnBR has significant power to discriminate among new physics models. arXiv1012.3893 Haisch, 2012 ETW: Kaon13, Ann Arbor, MI Bauer, et. al, 2009 Buras, et. al, 2005

  7. Experimental History ETW: Kaon13, Ann Arbor, MI E787/E949 Final(7 candidate events observed): Standard Model:

  8. Worldwide Effort • J-PARC E14 “KOTO” (K0p0nn) • Pencil beam decay-in-flight experiment • Improved J-PARC beam line • 2nd generation detector building on E391 at KEK • Re-using KTeVCsI crystals to improve calorimeter (better resolution and veto power) • Expect ~3 K0p0nn events (SM) • CERN NA-62 (K+p+nn) • Decay-in-flight experiment • Builds on NA-31/NA-48 • Expect ~55 K+p+nnevents per year (SM) with ~7 bg events per year for ~100 total events • Expect 10% measurement of K+p+nnBR • Complementary technique to ORKA ETW: Kaon13, Ann Arbor, MI

  9. Worldwide Effort • J-PARC E14 “KOTO” (K0p0nn) • Pencil beam decay-in-flight experiment • Improved J-PARC beam line • 2nd generation detector building on E391 at KEK • Re-using KTeVCsI crystals to improve calorimeter (better resolution and veto power) • Expect ~3 K0p0nn events (SM) • CERN NA-62 (K+p+nn) • Decay-in-flight experiment • Builds on NA-31/NA-48 • Expect ~55 K+p+nnevents per year (SM) with ~7 bg events per year for ~100 total events • Expect 10% measurement of K+p+nnBR • Complementary technique to ORKA ETW: Kaon13, Ann Arbor, MI See previous four talks!

  10. ORKA at FNAL • Stopped-kaon technique • Builds on successful BNL E787/949 experiments • 17 Institutions in 6 countries: Canada, China, Italy, Mexico, Russia, USA • 2 US National Labs, 6 US Universities • Leadership from successful rare kaon decay experiments ETW: Kaon13, Ann Arbor, MI

  11. BNL E787/E949 Stopped-Kaon Technique Measure everything! • K+ detected and decays at rest in the stopping target • Decay π+ track momentum analyzed in drift chamber • Decay π+ stops in range stack, range and energy are measured • Range stack straw chamber provides additional π+ position measurement in range stack • Barrel veto + End caps + Collar provide 4π photon veto coverage ETW: Kaon13, Ann Arbor, MI

  12. Difficult Measurement μ+ν BR 64% π+π0BR 21% • Observed signal is K+ π+μ+e+ • Background exceeds signal by > 1010 • Requires suppression of background well below expected signal (S/N ~10) • Requires π/μ/e particle ID > 106 • Requires π0 inefficiency < 10-6 ETW: Kaon13, Ann Arbor, MI II I Momentum spectra of charged particles from K+ decays in the rest frame

  13. Analysis Strategy (E747/E949) • Measure everything! • Separate analyses for PNN1 and PNN2 regions • Blind analysis • Blinded signal box • Final background estimates obtained from different samples than used to determine selection criteria (1/3 and 2/3 samples) • Bifurcation method to determine background from data • Use data outside signal region • Two complementary, uncorrelated cuts • Expected background << 1 event • Measure acceptance from data where possible ETW: Kaon13, Ann Arbor, MI

  14. ORKA:a 4th generation detector ETW: Kaon13, Ann Arbor, MI Expect ×100 sensitivity relative to BNL experiment: ×10 from beam and ×10 from detector

  15. Sensitivity Improvements: Beam • Main Injector • 95 GeV/c protons • 50-75 kW of slow-extracted beam • 48 × 1012 protons per spill • Duty factor of ~45% • # of protons/spill (×0.74) • Secondary Beam Line • 600 MeV/c K+ particles • Increased number of kaons/proton from longer target, increased angular acceptance, increased momentum acceptance (×4.3) • Larger kaonsurvival fraction (×1.4) • Increased fraction of stopped kaons (×2.6) • Increased veto losses due to higher instantaneous rate (×0.87) G4_beamline ×10 relative to E949 ETW: Kaon13, Ann Arbor, MI

  16. Sensitivity Improvements: Acceptance ETW: Kaon13, Ann Arbor, MI ×11 relative to E949

  17. ORKA K+p+nnSensitivity 210 events/year (SM) Fractional Error on Branching Ratio ETW: Kaon13, Ann Arbor, MI 5% measurement in 5 years (projected) Running Time (years)

  18. Other Physics Topics ETW: Kaon13, Ann Arbor, MI T: E787/949 thesis P: E787/949 paper “DP” = dark photon E787/949: 42 publications, 26 theses KTeV: 50 publications, 32 theses

  19. Experiment Site: B0 (CDF) • ORKA detector fits inside CDF solenoid • Re-use CDF solenoid, cryogenics, infrastructure • Requires new beam line from A0-B0 • CDF decommissioning in preparation for ORKA ongoing ETW: Kaon13, Ann Arbor, MI

  20. ILCroot Simulations K+p+p0 ETW: Kaon13, Ann Arbor, MI

  21. Detector R&D • ADRIANO fully-active calorimeter • Cerenkov light from layers of lead glass • Scintillation light from layers of plastic scintillator • Potential to improve photon-veto efficiency • Potential for particle identification • Tracking with GEM • Fast response & high rate capability • Relatively low cost, low HV, high gain • SiPM readout • Low cost, low HV, high gain • Operate in magnetic field • Double-pulse resolution? • Temperature sensitivity? • Coupling to scintillating fibers? Cerenkov p.e. ETW: Kaon13, Ann Arbor, MI GEM foil: 140μm 70μm

  22. ORKA Summary • High precision measurement of K+p+nnat FNAL MI • Expect ~1000 events and 5% precision on BR measurement with 5 years of data • Discovery potential for new physics at and above LHC mass scale • High impact measurement with 4th generation detector • Requires modest accelerator improvements and no civil construction • ORKA proposal: • http://www.fnal.gov/directorate/program_planning/Dec2011PACPublic/ORKA_Proposal.pdf ETW: Kaon13, Ann Arbor, MI Flavor community and US funding agencies are enthusiastic about ORKA and working to find a way to make it possible.

  23. Extra Slides ETW: Kaon13, Ann Arbor, MI

  24. π+μ+e+ Acceptance • E949 PNN1 π+μ+e+ acceptance: 35% • Improvements to increase acceptance relative to E949: • Increase segmentation in range stack to reduce loss from accidental activity and improve π/μ particle ID • Increase scintillator light yield by using higher QE photo-detectors and/or better optical coupling to improve μ identification • Deadtime-less DAQ and trigger so online π/μ particle ID unnecessary • Irreducible losses: ETW: Kaon13, Ann Arbor, MI

  25. Background (E747/E949) Charged particle for events passing PNN1 trigger Stopped kaon background: • K+ π+p0 • K+m+n • m+band • K+m+ng • K+m+p0n Beam background: • Single beam • Double beam • Charge exchange ETW: Kaon13, Ann Arbor, MI

  26. K+p+X0 • Many models for X0: familon, axion, light scalar pseudo-NG boson, sgoldstino, gauge boson corresponding to new U(1) symmetry, light dark matter … • K+p+nnis a background Upper limit on K+p+X where X has listed lifetime ETW: Kaon13, Ann Arbor, MI Upper limit on K+p+X where X is stable E787/E949

  27. K+p+X0 “event” • One event seen in E949 K+p+nnPNN1 signal region is near kinematic endpoint • Corresponds to a massless X0 • Central value of measured K+p+nn BR higher than SM expectation • Event consistent with SM K+p+nn, yet… • Interesting mode for further study ETW: Kaon13, Ann Arbor, MI Expected distribution of K+p+nn (MC) E949 signal event

  28. Precision Measurement of Ke2/Km2 • RSM = (2.477 ± 0.001) × 10-5 • Extremely precise because hadronic form factors cancel in ratio • Sensitive to new physics effects that do not share V-A structure of SM contribution • R = (2.488 ± 0.010) × 10-5 (NA62) • R = (2.493 ± 0.025 ± 0.019) × 10-5 (KLOE) • Expect ORKA statistical precision of ~0.1% • More study required to estimate total ORKA uncertainty ETW: Kaon13, Ann Arbor, MI

  29. Fundamental K+ Measurements • K+ lifetime • Not a major source of uncertainty for unitarity tests • Some discrepancies among experimental results in PDG • B(K+p+p0)/B(K+m+n) • Contributes to fit for |Vus/Vud| • Expect improvements in lattice calculations so that experimental errors may soon be dominant ETW: Kaon13, Ann Arbor, MI M. Moulson, CIPANP 2012 x 10-8 s

  30. Stage One Approval (Excerpt) ETW: Kaon13, Ann Arbor, MI

  31. NA62 ETW: Kaon13, Ann Arbor, MI

  32. KOTO ETW: Kaon13, Ann Arbor, MI Jiasen Ma, APS Meeting, March 2012

  33. ETW: Kaon13, Ann Arbor, MI

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