Status Report of DIRAC SPS and PS experiments Committee L. Nemenov 22 April 2008 DIRAC Addendum LIFETIME MEASUREMENT OF AND ATOMS TO TEST LOW-ENERGY QCD DIRAC collaboration CERN Geneva, Switzerland Zurich University Zurich, Switzerland Kyoto Sangyou University Kyoto, Japan Bern University Bern, Switzerland KEK Tsukuba, Japan Basel University Basel, Switzerland Santiago de Compostela University Santiago de Compostela, Spain University of Messina Messina, Italy IHEP Protvino, Russia Trieste University and INFN-Trieste Trieste, Italy SINP of Moscow State University Moscow, Russia INFN-Laboratori Nazionali di Frascati Frascati, Italy JINR Dubna, Russia Nuclear Physics Institute ASCR Rez, Czech Republic IFIN-HH Bucharest, Romania Institute of Physics ASCR Prague, Czech Republic Tokyo Metropolitan University Tokyo, Japan Czech Technical University Prague, Czech Republic 75 Physicists from 19 Institutes SPS and PS experiments Committee L. Nemenov 22 April 2008 Outline I. RUN Main tasks 2. Upgrade setup. 3. Characteristics of the new detectors. 4. Data taking. 5. Status of the data process. II. RUN Main tasks. 2. Status of the new electronics and DAQ. 3. RUN schedule. III. A 2 lifetime measurement and expected physical results after RUN 2008 and RUN SPS and PS experiments Committee L. Nemenov 22 April 2008 Plan for the run 2007 Tuning of all detectors downstream the magnet Start of the data taking towards the first observation of A K and A K 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. SPS and PS experiments Committee L. Nemenov 22 April 2008 Method of A K and A K observation and lifetime measurement Main features of the DIRAC set-up Thin targets: ~ 7 10 3 X 0, Nuclear efficiency: 3 10 4 Magnetic spectrometer Proton beam ~ proton/spill Resolution on Q: Q x Q y Q L 0.5 MeV/c atomic pairs (A K ) is too small to be measured directly e. m. interaction of A K in the target A K + K A K K + Q < 3MeV/c,, lab < 3 mrad Coulomb from short-lived sources non-Coulomb from long-lived sources free pairs Target Ni 98 m AKAK p 24 GeV/c p ++ KK SPS and PS experiments Committee L. Nemenov 22 April 2008 KK ++ Trajectories of and K + from the A K break-up The numbers to the right of the tracks lines are the and K + momenta in GeV/c The A K, and K + momenta are shown in the following table : P atom (GeV/c) P (GeV/c) P K (GeV/c) SPS and PS experiments Committee L. Nemenov 22 April 2008 Upgraded DIRAC experimental setup SPS and PS experiments Committee L. Nemenov 22 April 2008 Upgraded DIRAC experimental setup description SPS and PS experiments Committee L. Nemenov 22 April 2008 All Cherenkov detectors SPS and PS experiments Committee L. Nemenov 22 April 2008 Cherenkov detector C 4 F 10 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) SPS and PS experiments Committee L. Nemenov 22 April 2008 Cherenkov detector C 4 F 10 II Cherenkov detector quality factor N 0 = 125 cm -1 Efficiency to detect pions with momenta >4Gev is >99.5% SPS and PS experiments Committee L. Nemenov 22 April 2008 Aerogel Cherenkov detector I Responsibility: Zurich University (Zurich, Switzerland) SPS and PS experiments Committee L. Nemenov 22 April 2008 Aerogel Cherenkov detector II The n=1.008 counter Status: Aerogel detectors were installed on the setup Responsibility: Zurich University (Zurich, Switzerland) SPS and PS experiments Committee L. Nemenov 22 April 2008 Proton rejection efficiency for a cut in the ADC 20 channels above pedestal: 94.2 % for the heavy GeV/c 89.3 % for the light = 6-8 GeV/c Kaon detection efficiency for the same cut: 95.6 % for the heavy GeV/c 92.4 % for the light 6-8 GeV/c n=1.015 module N pe =6.9N pe =3.9 n=1.008 module Pure proton signal from decay and TOF separation Negative kaon spectrum for p= GeV/c Negative kaon spectrum for p = 6-8 GeV/c Aerogel: Kaon and proton signal III SPS and PS experiments Committee L. Nemenov 22 April Preshower detector I Responsibility: IFIN-HH (Bucharest, Romania) SPS and PS experiments Committee L. Nemenov 22 April 2008 Preshower detector II SPS and PS experiments Committee L. Nemenov 22 April 2008 Scintillation Fiber Detector I Sensitive area = 98.5 x 107 mm 2 SPS and PS experiments Committee L. Nemenov 22 April 2008 Scintillation Fiber Detector II Characteristics: Size of the plane 100100 mm 2 Thickness of the material for one plane 3 mm (1% X 0 ) Mean light output: 11 p.e. Mean Detector Efficiency: 98 % Time Resolution without coordinate and amplitude corrections 0.46 ns Space resolution 60 m New electronics (ADC-TDC for each channel) 960 channels SPS and PS experiments Committee L. Nemenov 22 April 2008 Number of channels tested with F1 SFD-X : 464 channels (out of 480) IH : all 64 channels Number of channels tested with F1 SFD-X : 464 channels (out of 480) IH : all 64 channels Optimum threshold SFD-X : ~1520 mV IH : ~20 mV Optimum threshold SFD-X : ~1520 mV IH : ~20 mV TDC channelADC channel Events TDC spectrum SFD Trigger peak Background ADC spectrum IH Thr = 20 mV Pedestal tail ADC spectrum SFD Pedestal + Single p.e. (light crosstalk) Thr = 10 mV Good events ~2.4 ns (FWHM) SFD and IH with new TDC/ADC beam test 2007 SPS and PS experiments Committee L. Nemenov 22 April 2008 Main features: High spatial accuracy < 30 m (2004 result); Distinguish two close tracks with distance < 200 m; Efficiency > 98% at I = 210 11 protons/spill; total detector thickness 2008 DIRAC:...after data collection in 2008 & ) > 2008 DIRAC:...after data collection in 2008 & 2009 Experimental results Low-energy QCD predictions for scattering lengths (s-wave) : 1) 2005 DIRAC: (PL B619, 50)...based on 2001 data (6530 observed atoms) Experiments A 2 lifetime: 2) 2008 DIRAC: preliminary...from major part data (13390 observed atoms) A K lifetime: : K: SPS and PS experiments Committee L. Nemenov 22 April 2008 Run 2009 will increase the statistics of A 2, A K and A K on factor 2.5 Run 2009 SPS and PS experiments Committee L. Nemenov 22 April 2008 The measurement of the s- wave K scattering lengths would test our understanding of the chiral SU(3) L SU(3) R symmetry breaking of QCD ( u, d and s quarks), while the measurement of scattering lengths checks only the SU(2) L SU(2) R symmetry breaking ( u, d quarks). What new will be known if K scattering length will be measured? K scattering This is the main difference between and K scattering! SPS and PS experiments Committee L. Nemenov 22 April 2008