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COMPASS Status report

COMPASS Status report. 2006 run : brief review. COMPASS 2007-2010 (Request to SPSC) - m -proton programme (T& L polarisations). - hadron run preparation (simulations). 2007 run : Status Conclusions. Reports to SPSC & requests. COMPASS Programme, 2007 to 2010

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COMPASS Status report

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  1. COMPASS Status report • 2006 run: brief review. • COMPASS 2007-2010 (Request to SPSC) - m-proton programme (T& L polarisations). - hadron run preparation (simulations). • 2007 run: Status • Conclusions FRC 4 September 2007

  2. Reports to SPSC & requests • COMPASS Programme, 2007 to 2010 CERN-SPSCC-2007-002 / SPSC-M-754 23 January 2007 • SPSC 80 Presentation by Alain M. • 6 February 2007 • The COMPASS Hadron programme CERN-SPSC-2007-015 / SPSC-M-755 12 April 2007 • SPSC 81 (Closed session) presentation by Stephan Paul17 April 2007 SPSC80 SPSC81 FRC 4 September 2007

  3. COMPASS Status, report to SPSC • COMPASS Status report 2007 CERN-SPSCC-2007-024 / SPSC-SR-022 20 June 2007 • SPSC 82 Presentation by Gerhard Mallot • 26 June 2007 SPSC82 FRC 4 September 2007

  4. K π RICH centre Target magnet acceptance. Event gains in 2006 wrt 2004 2004 2006 FRC 4 September 2007

  5. 2006 D* statistics (prelim.) • Compare: number of D* and effective signal Seff • Caveat: slightly different kinematics may influence event weight FRC 4 September 2007

  6. Beam delivery 2006 1010 events ‘physics’ events Protons on T6 beam line ok Protons used PS septum 25 ns Physics data taking ? FRC 1.09, 2006 FRC 4 September 2007

  7. Total beam delivered 3.8 1018 protons on T6 (thanks to SPS crew) Got 10 days commissioning and - 71% of beam expected for m-deuteronlongitudinal run, but - 0% for m-proton transverse run (postponed to 2007) Beam delivery in 2006 FRC 4 September 2007

  8. RICH and target upgrade fully successful Almost as many D* s in 2006 as in 2002-2004 If no surprises: Goal for m-deuteron longitudinal running in 2006 largely achieved 2006 performances FRC 4 September 2007

  9. Goals of the 2007 COMPASS m-proton run • Run with transversely polarised target - Collins (transversity) & Sivers asymmetries. Proton, only HERMES data at lower Q2 • Run with longitudinally polarized target - Flavour separated polarised PDFs, requires proton and deuteron (or neutron) data - g1 of the proton at small xBjorken FRC 4 September 2007

  10. Proton: only HERMES data at lower Q 2 Non-zero HERMES results transversityor HT? Goal: comparable statistics for: HERMES p COMPASSd COMPASS p Sivers asymmetry Proton Collins asymmetry AColl transversity PDF ~50% of stat. h+ h- SPSC-2007-015/M754 x FRC 4 September 2007

  11. Predicted errors (stat) for Du(x), Dd(x), Du(x), Dd(x) xDu xDd xDd xDu • COMPASS is unique at low x FRC 4 September 2007

  12. Predicted errors (stat) for Ds(x) HERMES: (0.023<x<0.6) Ds = + 0.028 ± 0.033 ± 0.009 xDs From COMPASS QCD analysis Ds + Ds = - 0.08 ± 0.01 ± 0.02 • Low x contribution to Ds needs to be measured FRC 4 September 2007

  13. Shape of g1 at small x unknown Reduce SMC error by about a factor 3 Fade of g1 at small x depends on gluon polarisation But good precision needed x range unique to COMPASS g1NS:Bjorken sum rule g1 of the proton at small x SMC E154 HERMES COMPASS SPSC-2007-015/M754 0.001 0.01 0.1 1 x FRC 4 September 2007

  14. The discussed physics goals require - Excellent spectrometer performance, similar to 2006 - Stable beam conditions for asymmetry measurements - ~1019 protons on T6 (SPSC-2007-015/M754,9.5 1018) Optimistically we can expect About 8.4 1018protons in 2007 Maybe more, if SPS/PS effi > 80 % m-proton run FRC 4 September 2007

  15. COMPASS hadron beam programme • Physics (Light Meson spectroscopy) • 1. Search for “constituent gluons” • - glueballs (gg, ggg) • - hybrids (qgq) • 2. Search for mesons with non qq quantum • numbers: “exotic mesons” • - tetra quarks (qqqq), molecules • Reactions • 1. Central production • (Pomeron scattering, couples to gluons) • 2. Diffractive excitation of projectile • 3. Photoproduction FRC 4 September 2007

  16. COMPASS hadron setup • Pixel GEMs to minimize • material in beam • Replaces Polarized Target • Radiation hard ECAL2 • (central part) FRC 4 September 2007

  17. COMPASS potential • High acceptance and efficiency for charged particles and photons. High counting rates (spectro. & DAQ-system) Excellent PID. • Observation of resonance(s) via # final states • and # production mechanisms • High energy of hadron beam(s) which allows us to access • MX > 1.8 GeV/c2 • Diffractive excitation & central production studied in parallel FRC 4 September 2007

  18. Precise result Good agreement with χPT Smaller than Serpukhov and Mainz result COMPASS Primakoff result (from 2004 Pilot-Hadron Run) χPT World data on απ SPSC81 (S.Paul) SPSC82 (G.Mallot) FRC 4 September 2007

  19. Intense ongoing work (simulation & analysis) Simulations for physics with hadron beam • Aim is to demonstrate that the COMPASS experiment is well prepared to adress the physics subjects to be studied with hadron beams • Status report at SPSC81 for Monte Carlo and MIPWA of mA mA’4p exclusive reaction • Memorandum for SPSC in preparation - simulation of centrally produced events - analysis of 2004 data on diffractive dissociation FRC 4 September 2007

  20. MC simulations and Partial Waves Analysis m-beam diffractive production, PWA with ideal & realistic detector SPSC81 (S.Paul) generated generated MC MC 1-- 2-- Reconstructed Reconstructed Reconstructed Reconstructed Reconstructed Reconstructed FRC 4 September 2007

  21. 2007 run: status of m-proton T& L data taking Prepar. T data taking PREPARATION Weeks 21 – 22 ~ 10 days TRANSVERSE Data Taking Week 23 (?) Weeks 25 – 32 ~ 45 days LONGITUDINAL Data Taking Weeks 32 today ~ 23 days L data taking T data taking FRC 4 September 2007

  22. Different target material NH3 (proton) Very long relaxation time (needed for T) High polarisations reached in 3-cell target 2007 Target + 92% + 88% - 83% FRC 4 September 2007

  23. m-p data taking • Transverse spin data taking From 18 June 2007 ~8h00 to 6 August 2007 8h00 Polarisation reversed by microwave, 3-cell P_configs : - + - / + - + /- + - /+ - + /- + - Σ SPS spills (data) : 120985 FRC 4 September 2007

  24. m-p data taking • Longitudinal spin data taking From 6 August 2007 ~12h00 to 3 September 2007 24h00 • Polarisation reversed by microwave, 3-cell P-configs: • - + - / + - + & Polarisation reversal by field rotation one per day Σ SPS spills (data) : 71353 (- + -) / 22279(+ - +) FRC 4 September 2007

  25. Conclusion • 2006 m-deuteron run with upgrades successful • Hard work ongoing (hardware & simulations) in preparation of hadron run in 2008 • 2007 m-proton run proceeds well. All possible efforts made to completem-data taking this year (?) FRC 4 September 2007

  26. Papers by COMPASS -18.01.05 Measurement of the spin structure of the deuteron in the DIS region. PLB 612 (2005) 154, CERN-PH-EP/2005-001, hep-ex/0501073 -10.02.05 First measurement of the transverse spin asymmetries of the deuteron in semi- inclusive deep inelastic scattering. PRL 94 (2005) 202002, CERN-PH-EP/2005-003 hep-ex/0503002 -5.03.05 Search for the F(1860) pentaquark at COMPASS. EPJ C41 (2005) 469-474, CERN-PH-EP/2005-009, hep-ex/0503033 -10.11.05 Gluon polarization in the nucleon from quasi-real photoproduction of high-pT hadron pairs. PLB 633 (2006) 25-32, CERN-PH-EP/2005-049, hep-ex/0511028 -21.12.06 The Deuteron Spin-dependent Structure Function g1d and its First Moment, PLB 647 (2007) 8-17, CERN-PH-EP/2006-029, hep-ex/0609038 Since last FRC FRC 4 September 2007

  27. Papers by COMPASS -11.09.06 A new measurement of the Collins and Sivers asymmetries on a transversely polarised target. NP B765 (2007) 31-70, CERN-PH-EP/2006-031, hep-ex/0610068 -28.11.06 The Compass Experiment at CERN. NIMA 577 (2007) 455-518, CERN-PH-EP/2007-001, hep-ex/0703049 -20.12.06 Spin asymmetry A1d and the spin-dependent structure function g1d of the deuteron at low values of x and Q2. PLB 647 (2007) 330-340, CERN-PH-EP/2006-040, hep-ex/0701014 -15.02.07 Double spin asymmetry in exclusive r0 muonproduction at COMPASS. Accepted EPJC, CERN-PH-EP/2007-009, hep-ex/0704.1863 -09.07.07 The Polarised Valence Quark Distribution from semi-inclusive DIS subm. PLB CERN-PH-EP/2007-024, hep-ex/0707.4077 FRC 4 September 2007

  28. Presentation at Conferences • 2006 54 presentations including 7(DIS06), 2(CIPANP06), 3(IHEP06), 11(SPIN06) … • 2007 46 presentations including 2(Moriond), 8(DIS07), 2(INPC2007), 2(Baryons07) … More to come. FRC 4 September 2007

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