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Rare Kaon Decays at the CERN SPS

Rare Kaon Decays at the CERN SPS. NA48-Future Working Group CERN-SPSC-2004-010 SPSC-EOI-002. NA48/1 Phase III Neutral hyperons (2006) NA48/3 K + → p + n n EOI for Villars NA48/4 K L → p 0 ee ( mm ) NA48/5 K L → p 0 n n. CERN-SPSC-2004-010.

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Rare Kaon Decays at the CERN SPS

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  1. Rare Kaon Decays at the CERN SPS NA48-Future Working Group CERN-SPSC-2004-010 SPSC-EOI-002 • NA48/1 Phase III Neutral hyperons (2006) • NA48/3 K+→p+n n EOI for Villars • NA48/4 KL→p0 ee (mm) • NA48/5 KL→p0n n CERN-SPSC-2004-010 Kaon Mini Workshop

  2. Kaon Rare Decays and the SM (holy grail) CP-Violation CP-Conservation Kaons provide quantitative tests of SM independent from B mesons Kaon Mini Workshop

  3. K+→p+nn : Theory • The hadronic matrix element can be extracted from • the well measuredK+→p0 e n • No long distance contributions QCD NLO Buchalla, Buras 1999 Prediction: BR(K+→ pnn) = 8.0 ± 1.1 × 10-11 Kaon Mini Workshop

  4. K+→p+nn : Experiment Region I Region II p+ in the K+ CM Kaon Mini Workshop

  5. AGS-E787/E949 K+→p+nn hep-ex/0403036 BR(K+→ p+ nn ) = 1.47+1.30-0.89 × 10-10 Kaon Mini Workshop

  6. NA48/3 • Build on the NA48 infrastructure and detectors to save on cost • Use a high energy (un-separated) kaon beam to simplify the rejection of K+→p+p0 Kaon Mini Workshop

  7. NA48/3: Layout 0.0 • Unseparated, positive beam of 75 GeV/c with DP/P~1% • Detectors upstream of the decay region: • Differential Cherenkov counter (CEDAR) to positively identify kaons • Beam spectrometer to make a redundant momentum measurement and to measure the kaon direction (KABES) • It requires ~100 ps time resolution. We are investigating: • Micromega-type chambers (already employed in NA48/2) • Silicon micro-pixel detectors • Detectors Downstream of the decay region • Double magnetic spectrometer for redundancy (with copy of NA48 dipole) • Charged hodoscope for timing • Hermetic photon vetoes (upgrade NA48 ring anti-counters) • High performance forward photon veto (NA48 LKr calorimeter) • Finely segmented Hadron Calorimeter/Muon veto Kaon Mini Workshop

  8. NA48/3: Beam layout 4 1012K+ decays In 90 days!! Kaon Mini Workshop

  9. Possible new high-intensity K+ beam for ‘NA48/3’ (K+→p+nn) Kaon Mini Workshop

  10. Detector Layout Kaon Mini Workshop

  11. K+→p+nn : NA48/3 (75 GeV/c) K+→m+n Region I K+→p+nn Region II K+→p+p+p- K+→p+p0 Kaon Mini Workshop

  12. NA48/3: Acceptance (Region I) Very Preliminary!! FLYO OO MC G. Ruggiero 5 % acceptance would translate into 20 events/year @BR~10-10 Kaon Mini Workshop

  13. Tests in 2004 • KABES beam spectrometer • 25 mm amplification gap MICROMEGAS • 1 Ghz FADC read-out (20 channels recuperated from the old NA48 proton tagger) • Silicon micro-pixels (ALICE) in beam similar to final beam • CEDAR Cherenkov counter • Test in M2 hadron beam? • Photon vetoes • Install small angle calorimeter (CMS-like crystals) • Collection of large sample of unbiased K+ p+p0 for validation • Drift chamber rate test (HV vs. resolution) • These tests require dedicated data taking • We have requested one extra week to the SPSC. Kaon Mini Workshop

  14. Outlook • We have established a Working Group • We plan to contribute to the Villars SPSC meeting 22-28 September • You can stay up-to-date joining the mailing list: na48-future@cern.ch Kaon Mini Workshop

  15. EXTRA MATERIAL Kaon Mini Workshop

  16. Some documentation is available on the Web (http://cern.ch/doble) : Beam Documentation for NA48 Please find below the updated geometry files (Beatch) for the P42 and K12 beams to NA48: . . . . . . . K12HIKA (dated 18/03/04) represents the latest tentative attempt to describe the layout of a high- acceptance, small momentum-bite (75.00.7 GeV/c) K+ beam for a possible future K+ -> pi+ nu nubar experiment (NA48/3). The beam is derived from the existing target station T10 along the present K12 beam line of length 102.0m to the exit of the final collimator. It features large-acceptance, radiation-resistant quadrupoles, a front-end achromat for momentum definition, a beam cleaning stage and a parallel section, incorporating a CEDAR differential Cerenkov counter to tag the K+, followed by a second achromat accommodating 3 spectrometer+tracking stations: KABES(1),(2)+(3). For the measurement of the decay pi+, the last 12m section of the decay-vacuum tank (blue tube) has been replaced by an additional (first) spectrometer comprising detectors: WC 1,2, 4 fore and aft of a (new) MNP33-1 magnet, followed by the present (second) spectrometer comprising: WC 3, 5,6 and the present MNP33-2 magnet, giving pT-kicks of +-210 MeV/c (deflecting the beam by +-2.8mrad.), respectively, resulting in a ~35 mm parallel displacement inside the beam tube. Photon veto counters with radial coverage of, respectively, 40 < r < 90mm (PHOT.VETO1) and r < 90mm (PHOT.2) are shown in front of the Kevlar window and at the end of the hall - following a ~10 mrad. beam deflecting magnet (MBPL101245) installed in place of the HAC. Kaon Mini Workshop

  17. CKM@MI22 GeV/c Separated Kaon beam p0 from K+p0p+of soft energy  not easy to veto In addition p0 is backward in CM very bulky vetoes Are required Kaon Mini Workshop

  18. NA48/3: Kaon Spectrometer Currently used in NA48/2: micromega via TPC read-out (KABES) NA48/2: @ 2 MHz/strip: Resolution strips 80 mm Risolution drift 50 mm Time resolution 0.7 ns Dead Time/strip 40 ns DP/P ~0.5 % • The expected rate per strip • in NA48/3 is about 10 times larger: • New micro-mesh (25 micron) • FADC • smaller strip size • New gas • Must test all of the above (2004?) Kaon Mini Workshop

  19. CEDAR Db/b ~ 1/2p (m22 –m12) Kaon Mini Workshop

  20. CEDAR Kaon Mini Workshop

  21. CEDAR Kaon Mini Workshop

  22. Kinematical Rejection F. Marchetto mm2 pp0 mn region 1 P(p+) (GeV/c) Region 1 -> signal region -> mm2 in the range between 0 and 0.01 (GeV/c2)2 mm2 = MK2 + mp2 – 2 ( EKEp – pKpp cosq) instead of mm2 = MK2 + mm2 – 2 ( EKEm – pKpp cosq) ~ 0 Kaon Mini Workshop

  23. mn pp0 10 GeV 20 GeV mm2 F. Marchetto • I = 1200 A • K smeared with • sp = 0.5 GeV/c • sq = sf = 15 mrad • being the angular resolution of the spectrometer ~17 mrad 30 GeV 40 GeV 60 GeV 50 GeV Kaon Mini Workshop

  24. Double spectrometer geometry Mag1 Mag2 Kevlar DCH1 DCH2 DCH3 DCH4 DCH5 DCH6 x q z 2m 10m 10m 10m 2.5m 2.5m 2.5m 2.5m G. Ruggiero Kaon Mini Workshop

  25. Alternative layout Kevlar Mag1 Mag2 DCH1 DCH2 DCH3 DCH4 DCH5 DCH6 x z 11m 9m 9m 2.5m 2.5m 2.5m 2.5m G. Ruggiero DCH1: • Straw tube in vacuum: X and Y view • Compass straw tube (real): per view • CKM straw tube (immaginary): per view Kaon Mini Workshop

  26. Square missing mass resolution • 50% improvement at “low momenta” • Better use of P measurement redundancy 7 m Single spectrometer 9 m Double spectrometer G. Ruggiero Kaon Mini Workshop

  27. Photon Rejection Energy distribution of the photon closer to beam axis Eg (GeV) L. Di Lella Kaon Mini Workshop

  28. Photon Vetoes (KAMI) Kaon Mini Workshop

  29. Muon Vetoes Kaon Mini Workshop

  30. Far Future: NA48/4KL→p0ee(mm) Kaon Mini Workshop

  31. NA48/4: KL→p0ee(mm) • Detector s(gg)×2 • Very ambitious, KTeV/NA48 already state of the art • KS-KL time dependent interference ×2 • Position experiment between 9 and 16 KS lifetimes (hep-ph/0107046) • KS-KL time independent interference ×3 • Assume constructive interference (theoretically preferred) • Data Taking ×5 • Run in “factory mode”. After all E799-II run only for a few months to collect ~7 × 1011KL decays • Beam intensity ×4 • Need ~1012 protons/sec, slowly extracted, high energy, DC • Tot ~ ×240 →sens on BR ~ ×15 (on Im lt ~×4-15) • close the gap between current upper limit and SM Kaon Mini Workshop

  32. SES ~ 10-10 Tantalisingly close to the SM prediction… …But progress is slow due to radiative backgrounds from KL→eegg State of the art: KTeV KL→p0ee Full Statistics: 1997+1999 1999 data BR(KL→ p0 ee ) < 2.8 × 10-10 @90%CL Kaon Mini Workshop

  33. Far future: NA48/5KL→p0nn Kaon Mini Workshop

  34. KL→p0n n (reminder) • Theoretical error ~2%: • Purely CP-Violating (Littenberg, 1989) • Totally dominated from t-quark • Computed to NLO in QCD (e.g. Buchalla Buras, 1999) • No long distance contribution SM~3 × 10-11 • Experimentally: 2/3 invisible final state !! • Best limit from KTeV using p0→eeg decay BR(K0→ p0nn) < 5.9 × 10-7 90% CL Still far from the model independent limit: BR(K0→ p0nn) < 4.4 × BR(K+→ p+nn) ~7 × 10-9 Grossman & Nir, PL B407 (1997) Kaon Mini Workshop

  35. E391a@PS-KEK • First dedicated experiment to search for KL→p0 nn • SES~ 3 10-10 • Based on pencil kaon beam and photon vetoes • Scheduled for ~100 days KEK PS beam in 2004 • This is a Stage I project for further study at J-PARC Kaon Mini Workshop

  36. KOPIO@BNL • Aim to collect 60 KL→p0 nn events with S/B~2 (Im ltto 15%) • Measure as much as possible • Energy, Position and Angle for each photon • Work in the Kaon Center of Mass • Micro-bunched AGS beam • Use TOF to measure KL momentum • Start construction in 2005? Kaon Mini Workshop

  37. NA48/5: KL→p0nn From KAMI proposal E391A J-PARC NA48/5 CERN may become competitive if the E391A technique works Kaon Mini Workshop

  38. A forward look…. K+→p+nn to 10% eK K0-K0bar mixing KL→p0nn (ee,mm) sin 2b Vub B tree decays Kaon Mini Workshop

  39. NA48-future@cern.ch Kaon Mini Workshop

  40. Current Status G. Isidori STILL A LARGE WINDOW OF OPPORTUNITY EXISTS Kaon Mini Workshop

  41. The Past: NA48 Kaon Mini Workshop

  42. NA48: Re e’/e=14.7 ± 2.2 10-4 Top 10 articles from Physics Letters B: • 1. The hierarchy problem and new dimensions at a millimeter http://dx.doi.org/10.1016/S0370-2693(98)00466-3 Physics Letters B, Volume 429, Issues 3-4 , 18 June 1998, Pages 263-272 Nima Arkani-Hamed, Savas Dimopoulos and Gia Dvali • 2. A precision measurement of direct CP violation in the decay of neutral kaons into twopions http://dx.doi.org/10.1016/S0370-2693(02)02476-0Physics Letters B, Volume 544, Issues 1-2 , 19 September 2002, Pages 97-112 J. R. Batley et al. (NA48 Collaboration) • 3. Has the GZK suppression been discovered? http://dx.doi.org/10.1016/S0370-2693(03)00105-9 Physics Letters B, Volume 556, Issues 1-2 , 13 March 2003, Pages 1-6, John N. Bahcall and Eli Waxman • 4. Testable scenario for relativity with minimum length http://dx.doi.org/10.1016/S0370-2693(01)00506-8 Physics Letters B, Volume 510, Issues 1-4 , 21 June 2001, Pages 255-263 Giovanni Amelino-Camelia • 5. Role of effective interaction in nuclear disintegration processes http://dx.doi.org/10.1016/S0370-2693(03)00801-3 Physics Letters B, Volume 566, Issues 1-2 , 24 July 2003, Pages 90-97 D. N. Basu • 6. Determination of solar neutrino oscillation parameters using 1496 days of Super-Kamiokande-I data http://dx.doi.org/10.1016/S0370-2693(02)02090-7 Physics Letters B, Volume 539, Issues 3-4 , 18 July 2002, Pages 179-187 S. Fukuda et al. • …. Kaon Mini Workshop

  43. The Future: NA48/3K+→p+nn Kaon Mini Workshop

  44. Importance of Villars SPSC Meeting From the address of R. Aymar, CERN CEO, to the CERN staff on 13/1/04: “… 4. Another goal [for 2004-2010] would be: • To define possible new fixed-target experiments, highly praised at another “Cogne” meeting in September 2004 • To decide in 2006 on the possible planning and the start of implementation of the Linac 4 and/or any proposed R&D or experiment, depending on the funds availableor expected at that time...” Kaon Mini Workshop

  45. Implications of Villars • Focus on a programme that can have a big impact (don’t be modest): • The reviewers will have a close look at the physics potential • Aim to a 10% measurement of |Vtd| via K+→p+n n • Since the time is very tight, use what is best best known • Start from NA48/2 and extrapolate to the ultimate experiment • To have a proposal evaluated by a Scientific Committee takes time • To seek approval in 2006 and take data in 2008 one has to act now • Express Interest now in order to protect assets such as: • Availability of ECN3 (the only high radiation area for SPS) • Availability of high intensity, slowly extracted protons from SPS • LKr calorimeter • Beam test as many things as possible in 2004 before the planned stop of the SPS in 2005 (2006?) Kaon Mini Workshop

  46. Kaon Mini Workshop

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