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Status Report of DIRAC

LIFETIME MEASUREMENT OF AND ATOMS TO TEST LOW-ENERGY QCD. SPS and PS experiments Committee L. Nemenov 22 April 2008. Status Report of DIRAC. DIRAC Addendum. SPS and PS experiments Committee L. Nemenov 22 April 2008. DIRAC collaboration.

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Status Report of DIRAC

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  1. LIFETIME MEASUREMENT OF AND ATOMS TO TEST LOW-ENERGY QCD SPS and PS experiments Committee L. Nemenov22 April 2008 Status Report of DIRAC DIRAC Addendum

  2. SPS and PS experiments Committee L. Nemenov22 April 2008 DIRAC collaboration 75 Physicists from 19 Institutes CERN Geneva, Switzerland Tokyo Metropolitan University Tokyo,Japan Czech Technical University Prague, Czech Republic IFIN-HHBucharest, Romania Institute of Physics ASCR Prague, Czech Republic JINRDubna, Russia Nuclear Physics Institute ASCR Rez, Czech Republic SINP of Moscow State UniversityMoscow, Russia INFN-Laboratori Nazionali di FrascatiFrascati, Italy IHEPProtvino, Russia Trieste University and INFN-TriesteTrieste,Italy Santiago de Compostela UniversitySantiago de Compostela,Spain University of MessinaMessina, Italy Basel UniversityBasel,Switzerland KEKTsukuba, Japan Bern University Bern,Switzerland Zurich University Zurich,Switzerland Kyoto Sangyou UniversityKyoto, Japan

  3. SPS and PS experiments Committee L. Nemenov22 April 2008 Outline I. RUN 2007. 1. Main tasks 2. Upgrade setup. 3. Characteristics of the new detectors. 4. Data taking. 5. Status of the data process. II. RUN 2008. 1. Main tasks. 2. Status of the new electronics and DAQ. 3. RUN schedule. III. A2π lifetime measurement and expected physical results after RUN 2008 and RUN 2009.

  4. SPS and PS experiments Committee L. Nemenov22 April 2008 Plan for the run 2007 • Tuning of all detectors downstream the magnet • Start of the data taking towards the first observation ofAπKandAKπ • Tuning of the Scintillating Fiber Detector and the Ionization hodoscope with the new electronics in parallel with data taking. • Tuning of the Micro Drift Chambers in parallel with data taking.

  5. SPS and PS experiments Committee L. Nemenov22 April 2008 Method of AπK and AKπ observationand lifetime measurement (AπK) is too small to be measured directly e. m. interaction of AπK in the target AπK → π+K− AKπ → K+π− Q < 3MeV/c, ,Θlab< 3 mrad • Coulombfrom short-lived sources • non-Coulombfrom long-lived sources Target Ni 98 m π+ p AπK “atomic pairs” 24 GeV/c K− π+ p “free pairs” 24 GeV/c K− Main features of the DIRAC set-up Thin targets: ~ 7 ×10–3 X0, Nuclear efficiency: 3 ×10−4 Magnetic spectrometer Proton beam ~ 1011proton/spill Resolution on Q: Qx≈ Qy≈ QL≈ 0.5 MeV/c

  6. SPS and PS experiments Committee L. Nemenov22 April 2008 Trajectories of π− and K+from the AπK break-up The numbers to the right of the tracks lines are the πand K+momentain GeV/c The AKπ, π−and K+momentaare shownin the following table:

  7. SPS and PS experiments Committee L. Nemenov22 April 2008 Upgraded DIRAC experimental setup

  8. SPS and PS experiments Committee L. Nemenov22 April 2008 Upgraded DIRAC experimental setup description

  9. SPS and PS experiments Committee L. Nemenov22 April 2008 All Cherenkov detectors

  10. SPS and PS experiments Committee L. Nemenov22 April 2008 Cherenkov detector C4F10 I Responsibility:JINR (Dubna, Russia) with participation of INFN (Frascati National Lab, Italy); IFIN-HH (Bucharest, Romania); Zurich University (Zurich, Switzerland); Adviser: O. Ullaland (CERN)

  11. SPS and PS experiments Committee L. Nemenov22 April 2008 Cherenkov detector C4F10 II Cherenkov detector quality factor N0= 125cm-1 Efficiency to detect pions with momenta >4Gev is >99.5%

  12. SPS and PS experiments Committee L. Nemenov22 April 2008 Aerogel Cherenkov detector I Responsibility: Zurich University (Zurich, Switzerland)

  13. SPS and PS experiments Committee L. Nemenov22 April 2008 Aerogel Cherenkov detector II Responsibility: Zurich University (Zurich, Switzerland) Then=1.008 counter Status: Aerogel detectors were installed on the setup

  14. Aerogel: Kaon and proton signal III SPS and PS experiments Committee L. Nemenov22 April 2008 Negative kaon spectrum for p=4.5 -5 GeV/c Pure proton signal from Λ decay and TOF separation Negative kaon spectrum for p = 6-8 GeV/c n=1.008 module n=1.015 module Npe =6.9 Npe =3.9 • Proton rejection efficiency for a cut in the ADC 20 channels above pedestal: • 94.2 % for the heavy aerogel @p= 4.5-5 GeV/c • 89.3 % for the light aerogel @p = 6-8 GeV/c • Kaon detection efficiency for the same cut: • 95.6 % for the heavy aerogel @p= 4.5-5 GeV/c • 92.4 % for the light aerogel @p= 6-8 GeV/c 0 2 4 8 10 6

  15. SPS and PS experiments Committee L. Nemenov22 April 2008 Preshower detector I Responsibility:IFIN-HH (Bucharest, Romania)

  16. SPS and PS experiments Committee L. Nemenov22 April 2008 Preshower detector II

  17. SPS and PS experiments Committee L. Nemenov22 April 2008 Scintillation Fiber Detector I Sensitive area = 98.5 x 107 mm2

  18. SPS and PS experiments Committee L. Nemenov22 April 2008 Scintillation Fiber Detector II Characteristics: Size of the plane100×100 mm2 Thickness of the material for one plane3 mm (1% X0) Mean light output:≈ 11 p.e. Mean Detector Efficiency:≈ 98 % Time Resolution without coordinate and amplitude corrections≈0.46 ns Space resolutionσ ≈ 60 m New electronics (ADC-TDC for each channel) 960 channels

  19. TDC spectrum SFD ADC spectrum SFD ADC spectrum IH Thr = 10 mV Thr = 20 mV Trigger peak Pedestal + Single p.e. (light crosstalk) Good events ~2.4 ns (FWHM) Events Events Events Good events Background Pedestal tail TDC channel ADC channel ADC channel SPS and PS experiments Committee L. Nemenov22 April 2008 SFD and IH with new TDC/ADC beam test 2007 • Number of channels tested with F1 • SFD-X : 464 channels (out of 480) • IH : all 64 channels • Optimum threshold • SFD-X : ~15–20 mV • IH : ~20 mV

  20. Micro Drift Chambers I SPS and PS experiments Committee L. Nemenov22 April 2008 Responsibility:JINR (Dubna, Russia), Basel University (Basel, Switzerland) Main features: High spatial accuracy σ < 30 µm (2004 result); Distinguish two close tracks with distance < 200 µm; Efficiency > 98% at I = 2×1011protons/spill; total detector thickness <5×10-3X0; time resolution < 1 ns; readout time < 3 s.

  21. Micro Drift Chambers II SPS and PS experiments Committee L. Nemenov22 April 2008 Online data 2007 Target: Pt (28µm) Intensity: 2x1011 Examples of event Status During 2007 run Micro Drift Chambers with the new electrodes and all electronics were finally implemented into the DIRAC setup and DAQ system. Data with different MDC working condition were collected.

  22. Micro Drift Chambers III SPS and PS experiments Committee L. Nemenov22 April 2008 Beam profile, reconstructed by MDC Drifttime: τ ~ 23ns

  23. SPS and PS experiments Committee L. Nemenov22 April 2008 Run 2007 • Improvement of the proton beam time structure and the beam intensity distribution at spills. R.Steerenberg, A.Grudiev, L.Gatignon et al. • Beam intensity about 1.91011 proton/spill 1st level triggers numbers 3200(π+π−)+2100(K+π−)+1000(π+K−)=6300 1/spill • Number of recorded events 2000 1/spill is near to the hardware limit of DAQ • Full number of π+π−and πK events recorded during 3 months of data taking is1.4109

  24. SPS and PS experiments Committee L. Nemenov22 April 2008 Estimation ofAKandAKatom fluxes First estimation of A2π observed in 2007 with Pt target: 10000±3000 (with suppression factor 2 in respect to πK atom trigger) From theory and FRITIOF6 simulation production of atoms relates as: Assuming an additional factor of inefficiency for kaonic atoms of 2 and using expected value of the lifetime 3.7 fs we estimate the number of collected kaonic atoms:nAπK +nAKπ= 700 ± 200. This value coincides with the estimations made in Addendum and reported at SPSC last year. Before autumn 2008 we will prepare a paper titled: “Search for πK atoms” or “Observation of πK atoms”

  25. SPS and PS experiments Committee L. Nemenov22 April 2008 RUN 2008 Main tasks. • To tune DIRAC setup with the new front-end electronics, trigger logic, readout system and DAQ • To perform data taking for the lifetime measurement of A2π , AKπ and AπK

  26. HH SFD VH … Č ADC-TDC (D412) ADC-TDC (D412) ADC-TDC (D412) ADC-TDC (D412) ADC-TDC (D412) Experimental Area Transmitter (1st level) Transmitter (2nd level) Transmitter (1st level) Transmitter (1st level) Transmitter (1st level) Transmitter (1st level) Transmitter (2nd level) 2 2 1 1 1 1 2 1 2 2 2 1 USB hubs Logical output signals for trigger (flat cables) USB Barrack ADC&TDC signals for readout (maximal distance ~10 m) Host computer Central storage (IT division) SPS and PS experiments Committee L. Nemenov22 April 2008 Front-end electronics and Readout System Responsibility:JINR (Dubna, Russia) with participation of IFIN-HH (Bucharest, Romania); Zurich University (Zurich, Switzerland)

  27. SPS and PS experiments Committee L. Nemenov22 April 2008 Status of the new electronics • All electronics is ready, tuned and will be installed before the rung beginning • The setup tuning, in according to our plan, will be done during 6 weeks Data taking will continue 4 months

  28. SPS and PS experiments Committee L. Nemenov22 April 2008 Pion scattering lengths Low-energy QCD predictions for ππscattering lengths (s-wave): Experiments *) using Roy equations K →π+π e+ve(Ke4): 1) 1977 Geneva-Saclay: (PR D15, 574) *) *) 2) 2001 E865 / BNL: (PRL 87, 221801) *) 3) 2008 NA48 / 2: (EPJ C54, 411) K →π0π0π+: 2006 NA48 / 2: (PL B633, 173)

  29. SPS and PS experiments Committee L. Nemenov22 April 2008 Experimental results 2001-2003

  30. SPS and PS experiments Committee L. Nemenov22 April 2008 Experimental results Low-energy QCD predictions forscattering lengths (s-wave): ππ: πK: Experiments A2π lifetime: 1) 2005 DIRAC: (PL B619, 50)...based on 2001 data (6530 observed atoms) 2) 2008 DIRAC: preliminary...from major part 2001-03 data (13390 observed atoms) 3)>2008 DIRAC: ...after data collection in 2008 & 2009 AπK lifetime: >2008 DIRAC: ...after data collection in 2008 & 2009

  31. SPS and PS experiments Committee L. Nemenov22 April 2008 Run 2009 Run 2009 will increase the statistics of A2π,AπK andAKπon factor2.5

  32. K scattering SPS and PS experiments Committee L. Nemenov22 April 2008 What new will be known if K scattering length will be measured? The measurement of the s-waveπKscattering lengths would test our understanding of the chiralSU(3)L SU(3)Rsymmetry breaking of QCD(u, dandsquarks),while the measurement of ππ scattering lengths checks onlythe SU(2)L SU(2)Rsymmetry breaking(u, dquarks). This is the main difference betweenππandπKscattering!

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