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COMPASS DRELL-YAN PROGRAM T.Iwata Department of Physics, Yamagata University

COMPASS DRELL-YAN PROGRAM T.Iwata Department of Physics, Yamagata University. J-PARC meeting at RIKEN, 7-8, April, 2008,. OUTLINE. COMPASS Experiment at CERN Motivation of Drell-Yan Measurements Drell-Yan Program in COMPASS Polarized Target for the Drell-Yan Program

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COMPASS DRELL-YAN PROGRAM T.Iwata Department of Physics, Yamagata University

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  1. COMPASS DRELL-YANPROGRAMT.Iwata Department of Physics, Yamagata University J-PARC meeting at RIKEN, 7-8, April, 2008,

  2. OUTLINE • COMPASS Experiment at CERN • Motivation of Drell-Yan Measurements • Drell-Yan Program in COMPASS • Polarized Target for the Drell-Yan Program • Drell-Yan Beam Test • Outlook • Summary JPARC-meeting at RIKEN, 7-8, April, 2008

  3. LHC SPS COMPASS EXPERIMENT AT CERN COmmonMuon andProton Apparatus forStructure and Spectroscopy • Nucleon structure • Hadron spectroscopy • Common spectrometer • Polarized muon and hadron beams COMPASS 1. Muon running to study nucleon spin structure, 2002～2007 2. Hadron running 2008～ JPARC-meeting at RIKEN, 7-8, April, 2008

  4. COMPASSSETUP • two stages spectrometer • Large Angle Spectrometer (SM1) • Small Angle Spectrometer (SM2) • tracking, calorimetry, RICH(PID) SciFi Silicon Micromegas GEMs Straws SDC MWPC W45 Muon Filter 2 SM2 E/HCAL E/HCAL SM1 Polarized Target Muon Filter 1 ＮＨ３／6LiD RICH mbeam • High rate capability • Wide kinematical range • Large acceptance X(min.)~0.002 160GeV, polarized (PB~80%) (hadrons are available) JPARC-meeting at RIKEN, 7-8, April, 2008

  5. dN/dz 4000 2000 0 -1000 0 1000 zvtx (mm) THE POLARIZED TARGET SYSTEM SOLID POLARIZED TARGET WITH DNP Polarization: P(H)~90%, P(D)~55% proton : NH3 deuteron : 6LiD LONGITUDINAL & TRANSVERSE SPIN MODES 2002 -2004 Old SMC Magnet 2006 -2007 New COMPASS magnet with a large aperture Superconductive magnet Dipole (0.5 T) Solenoid (2.5 T) Dipole (0.5 T) Solenoid (2.5 T) 30 cm 60 cm two 60 cm long cells with opposite polarization 3 cells (30-60-30 cm) with (+,-,+) polarization configuration 3He – 4He Dilution refrigerator (T~50mK) THE WORLD LARGEST POLARIZED TARGET JPARC-meeting at RIKEN, 7-8, April, 2008

  6. THE TARGET PART Dilution refrigerator Beam Magnet SciFi tracker JPARC-meeting at RIKEN, 7-8, April, 2008

  7. THE RICH DETECTOR 3 m mirrors 6 m photon detectors 5 m C4F10 threshold momenta • pp = 2 GeV/c • pK = 9 GeV/c • pP =17 GeV/c Beam C4F10 • 80 m3 (3 m C4F10 gas radiator) • 116 mirrors • 5.3 m2 photon detector • central part • 576 PMTs with lenses, 16ch/PMT • outer part • MWPC CsI photo cathodes(8x8 mm2 pads) inner region only JPARC-meeting at RIKEN, 7-8, April, 2008

  8. MOTIVATION OF DRELL-YANMEASUREMENTS

  9. NUCLEON PARTONIC STRUCTURE What is the nucleon partonic structure? theoretical base: QCD Nucleon spin puzzle Origin of the spin? • GLUON SPIN CONTRIBUTION study on going • ORBITAL component to be studied in GPD-experiments NOT WELL KNOWN QUARK DISTRIBUTIONS should be studied Transverse spin dependent distributions, Transverse Momentum Dependent(TMD) distributions JPARC-meeting at RIKEN, 7-8, April, 2008

  10. QUARK DISTRIBUTIONS @ twist 2 Nucleon long. pol. trans. pol. unpol. number density Sivers unpol. Nucleon T-odd Parton helicity long. pol. Quark transversity Boer-Mulders trans. pol. T-odd JPARC-meeting at RIKEN, 7-8, April, 2008

  11. QUARK DISTRIBUTION STUDY IN SIDIS SIDIS Transversity Transversity Collins fragmentation function Sivers PDF (TMD) Sivers PDF Related to orbital angular momentum of quarks In SIDIS, PDFs appear accompanied with fragmentation functions un-polarized fragmentation function JPARC-meeting at RIKEN, 7-8, April, 2008

  12. QUARK DISTRIBUTION STUDY IN DY Drell-Yan is alternative way to study quark distributions Advantage: NO NEED OF ANY FRAGMENTATION FUNCTIONS Double polarized Drell-Yan direct extraction of TRANSVERSITY planned at GSI But, a big challenge experimentally JPARC-meeting at RIKEN, 7-8, April, 2008

  13. QUARK DISTRIBUTION STUDY IN DY unpol. DY FF free cos2 modulation relates to Boer-Mulders function single polarized DY B.M. function Transversity prediction Collins , PL B536 (2002) 43 Unpol. PDF Siverse function JPARC-meeting at RIKEN, 7-8, April, 2008

  14. DY KINEMATICS lepton pair CM frame hadron plane lepton plane P1,P2 incoming hadrons VALENCE REGION probed in COMPASS nucleon spin vector qT :transvese momentum of virtual photon case JPARC-meeting at RIKEN, 7-8, April, 2008

  15. UN-POLARIZED DRELL-YAN unpolarized Drell-Yan : qT weighted angular distribution Boer-Mulder for anti-q in p Boer-Mulder for q in proton 1st moment of the PDFs: Number densities (well known) A.Sissakian et al., Phys. Rev. D72, 054027 (2005) JPARC-meeting at RIKEN, 7-8, April, 2008

  16. SINGLE SPIN ASYMMETRIES single polarized Drell-Yan : trans. mom. of photon nucleon Spin vector qT weighted SSA transversity Sivers JPARC-meeting at RIKEN, 7-8, April, 2008

  17. SINGLE SPIN ASYMMETRIES transversity Boer-Mulder func. for p number densities (well known) 1st moment of number density for p Sivers func. number densities (well known) A.Sissakian et al., Phys. Rev. D72, 054027 (2005) JPARC-meeting at RIKEN, 7-8, April, 2008

  18. DRELL-YAN PROGRAM IN COMPASS

  19. DY PROGRAM IN COMPASS • Beam: p– @ 1x107p/s ( = 5x107p/spill) • Intensity limited at least by radiation regulation at the EXP. hall • Polarised proton target (NH3) • Spectrometer (the running spectrometer): • Good hadron/electron/muon separationin the final state • Large muon/electron acceptance • High capacity DAQ system • High rate trackers in the beam region • Open structure ( contrary to conventional DY experiments) •  DY in multi-channels( muon-, electron-, hadron-pairs) JPARC-meeting at RIKEN, 7-8, April, 2008

  20. DY EVENT RATE - Target: NH3 and LNH3=15 cm x 2, ( NH3 : 0.85 g/cm3) - PT material filling factor Ff = 0.6 - Number of nucleon in NH3 molecule: ANH3 =17 - beam intensity: Ibeam = 1107 pions/s - NA = 6.0 ×1023 mol-1 Luminosity: L = LNH3 × Ncell × NH3 × Ff × NA × 1/ANH3 × Ibeam =1.1×1031 cm-2 s-1 - reconstruction efficiency (acceptance incl.) : A ≈ 0.4 - DY cross section on NH3: NH3 = Nnucl × p , where Nnucl=17 • Dspill = 5 s (duration of spill), Nspill =4000 (number of spills per day), • Esps= 80% (efficiency of the machine) - Duration of the Run 150 days: DRUN=150 R = L × Nnucl × p × A × Dspill × Nspill × ESPS × DRUN JPARC-meeting at RIKEN, 7-8, April, 2008

  21. STATISTICS VERY PRELIMINARY 150 days of running Cross section values were taken from AB_5 A.Bianconi generator cross-checked with PYTHIA data (A.Nagaytsev, Dubna), without J/ contribution JPARC-meeting at RIKEN, 7-8, April, 2008

  22. KEY ISSUES & TASKS • PT with the hadron beam at relatively high intensity • high polarization shoud be kept in transverse spin mode , • P>70% for a week in frozen spin mode (<100mK, @ 0.6T) • New muon trigger system in Large Angle Spectrometer • Drift tube array or a scintillation hodoscope • ( present system in Small Angle Spectrometer is also used) • Background ? • muon channel: background from pion decay • studiedby simulation & beam test JPARC-meeting at RIKEN, 7-8, April, 2008

  23. POLARIZED TARGET FORDRELL-YAN PROGRAM Takahiro Iwata JPS meeting at Sapporo, September 22, 2007

  24. POLARIZED TARGET FOR DY TRANSVERSELY POLARIZED target required • COMPASS PT operation: • Polarization enhancement only in longitudinal spin mode (2.5T) • Transverse spin mode given in frozen spin mode(<100mK, B~0.6T) • Need long relaxation time ; low temperatures essential HEAT INPUT p- beam (~ 107 particles/s) increasing temperature decreasing relaxation time local temperature increase • hadronic interactions with high probability • secondary particles(multiplicity?) • small spot size available (sx=sy~5mm) Limit beam intensity TARGET MATERIAL NH3 high polarization, high dilution factor, long relaxation time TARGET SIZE 2 target cells, 20~30cm long JPARC-meeting at RIKEN, 7-8, April, 2008

  25. Nm : Multiplicity=3 r : density k : Packing factor L : length of single cell =20cm EMIP : 2 MeV· cm2/g 5 mW at 75mK Ibeam : Beam intensity TOTAL HEAT INPUT V.S. COOLING POWER • Qtotal = Nm · (rm·k+rHe·(1 - k)) · 2L · EMIP · Ibeam removed by the dilution refrigerator mK measured cooling power • Qtotal = 0.6mW mmol/sec 3He flow rate (mmol/sec) rough estimation THE REFRIGERATOR HAS SUFFICIENT COOLING POWER JPARC-meeting at RIKEN, 7-8, April, 2008

  26. 1 x 107 /s. BEAM SPOTSIZE V.S. TEMPERATURE should be below 100 mK. (20 + 20 )cm configuration JPARC-meeting at RIKEN, 7-8, April, 2008

  27. ENERGY DEPOSITION FROM SIMULATION targets cells(NH3) Simulation code: FLUKA Liquid He cell configuration: (20 + 20 )cm z(cm) 190 GeVp- Gaussian beam sx = sy = 0.5cm beam 3cm beam spot DE~4.0 x 10-2GeV DE~4.9 x 10-2GeV Cavity #2 Cavity #3 Cavity #1 GeV/cm3 per primary done by H. Vincke and E. Feldbaumer Total heat input : ~0.4mW JPARC-meeting at RIKEN, 7-8, April, 2008

  28. BEAM TESTFOR DY PROGRAM Takahiro Iwata JPS meeting at Sapporo, September 22, 2007

  29. DRELL-YAN BEAM TEST performed @ 11-12 November 2007 Feasibility study of the DY program with COMPASS spectrometer using 160 GeV negative pion beam • Radiation conditions • with COMPASS PT (full length (120cm) ~ 1 int. length) • @ hadron beam intensity 2×107/spill  L ~10 31 cm-2 s-1 ( ~ eq. to 108 /spill on 0.25 int.length. PT) • - Performance of spectrometer & polarized target during the operation of high intensity hadron beam • J/ event rates (normalization for DY and background) • - Background/Signal level and trigger rates JPARC-meeting at RIKEN, 7-8, April, 2008

  30. RADIATION CONDITON 2.2×107 pions per spill (supercycle time 20.4s) No (additional) activation of beam line components was found 4.0 uSv/h 1.0 uSv/h 6.3 uSv/h Beam 0.3 uSv/h 1.3 uSv/h 1.0 uSv/h 0.5 uSv/h dose rate below the limit (15 uSv/h) Control rooms Target JPARC-meeting at RIKEN, 7-8, April, 2008

  31. SPECTROMETER CONDITON @ High intensity ( 2.2×107/spill) • Generally very stable behavior • Most of detectors were operated with the muon running set up. • Only two drift chambers were tripped: • (trip currents were not adjusted) • Higher currents/rates wrt to muon running were observed only for the tracking station right behind the SM1 (not a surprise) – Straws, DC’s JPARC-meeting at RIKEN, 7-8, April, 2008

  32. DI-MUON MASS SPECTRUM Very first J/ signal Data taking: 1 shift(8 hours) ~1/3 of events analyzed No cut tuning J/ yield close to expected COMPASS DY-TEST2007 di-muon mass (pp @ 450 GeV) JPARC-meeting at RIKEN, 7-8, April, 2008

  33. PT BEHAVIOR WITH PION BEAM TEMPERATURE The behavior is compatible with that for the muon beam(@108/spill) 2 x 107 p/spill magnet  1x 107 p/spill Target spin maintained at 1T in longitudinal mode NO DEPOLARIZATION SEEN as expected Beam tuning NOTE: ON-beam temperatures do not show the real temperatures of the target, but they are sensitive to the beam intensity. 1 spill = ~ 5 sec JPARC-meeting at RIKEN, 7-8, April, 2008

  34. SUMMARY OF THE BEAM TEST • Radiation safety regulation is fulfilled. • Spectrometer & polarized target are operational with the hadron beam. • Indication of the J/psi demonstrates feasibility of the DY experiment with COMPASS apparatus. JPARC-meeting at RIKEN, 7-8, April, 2008

  35. OUTLOOK Takahiro Iwata JPS meeting at Sapporo, September 22, 2007

  36. MILESTONES • DY physics with COMPASS spectrometer • Expression of Interest(EoI): in April, 2008 • Merging with the GPD measurements • Letter of Intent(LoI): by the end of 2008 • Proposal : 2009 • upgrade of the apparatus: 2009 • Modification of PT cell structure • Implementation of Muon trigger system in LAS • Modification of the central part of ECal1 • First DY data after 2010 JPARC-meeting at RIKEN, 7-8, April, 2008

  37. SUMMARY • Pol. DY experiment is a new and alternative way to study detailed quark distributions. • Fragmentation function free measurements can be performed. • COMPASS has preferable environment for DY with the hadron beam & the polarized target. • Preparation of the experiment is on going. • The beam test demonstrated feasibility of the experiment. • Proposal will be ready for submission in 2009 • First data of DY will be after 2010. JPARC-meeting at RIKEN, 7-8, April, 2008

  38. BACKUP SLIDES JPARC-meeting at RIKEN, 7-8, April, 2008

  39. 5 x 107 muons/spill 1 x 107 pions/spill Multiplicity ~ 5 with 30-60-30cm long 2 x 108 muons/spill 5 x 107 muons/spill Multiplicity measurement by temperature sensors JPARC-meeting at RIKEN, 7-8, April, 2008

  40. ACCEPTANCE 3.5 GeV <= M <= 9.0 GeV 200 GeV - beam (S=375 GeV2) JPARC-meeting at RIKEN, 7-8, April, 2008

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