COMPASS DRELL-YAN PROGRAM COMPASS DRELL-YAN PROGRAM T.Iwata Department of Physics, Yamagata University J-PARC meeting at RIKEN, 7-8, April, 2008, JPARC-meeting at RIKEN, 7-8, April, 2008 OUTLINE Takahiro Iwata 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 COMPASS EXPERIMENT AT CERN Takahiro Iwata LHCSPS COMPASS CO mmon M uon and P roton A pparatus for S tructure and S pectroscopy Nucleon structure Hadron spectroscopy Common spectrometer Polarized muon and hadron beams 1. Muon running to study nucleon spin structure, 2002 Hadron running 2008 Takahiro IwataJPARC-meeting at RIKEN, 7-8, April, 2008 SM1 SM2 beam Muon Filter 1 E/HCAL RICH Polarized Target SciFi Silicon Micromegas GEMs Straws SDC MWPC W45 COMPASS SETUP two stages spectrometer Large Angle Spectrometer (SM1) Small Angle Spectrometer (SM2) tracking, calorimetry, RICH(PID) High rate capability Wide kinematical range Large acceptance X(min.)~ GeV, polarized (P B ~80%) 6 LiD Muon Filter 2 (hadrons are available) dN/dz 2000 z vtx (mm) New COMPASS magnet with a large aperture Old SMC Magnet 60 cm30 cm THE POLARIZED TARGET SYSTEM Superconductive magnet Solenoid (2.5 T) 3 He 4 He Dilution refrigerator (T~50mK) Dipole (0.5 T) two 60 cm long cells with opposite polarization 3 cells ( cm) with (+,-,+) polarization configuration Solenoid (2.5 T) Dipole (0.5 T) proton : NH 3 deuteron : 6 LiD Polarization: P(H)~90%, P(D)~55% LONGITUDINAL & TRANSVERSE SPIN MODES Takahiro IwataJPARC-meeting at RIKEN, 7-8, April, 2008 THE WORLD LARGEST POLARIZED TARGET SOLID POLARIZED TARGET WITH DNP Takahiro IwataJPARC-meeting at RIKEN, 7-8, April, 2008 Beam Dilution refrigerator Magnet SciFi tracker THE TARGET PART THE RICH DETECTOR 5 m 6 m 3 m C 4 F 10 photon detectors mirrors threshold momenta p = 2 GeV/c p K = 9 GeV/c p P =17 GeV/c Takahiro IwataJPARC-meeting at RIKEN, 7-8, April, 2008 C 4 F 10 inner region only 80 m 3 (3 m C 4 F 10 gas radiator) 116 mirrors 5.3 m 2 photon detector central part 576 PMTs with lenses, 16ch/PMT outer part MWPC CsI photo cathodes(8x8 mm 2 pads) Beam MOTIVATION OF DRELL-YAN MEASUREMENTS Takahiro IwataJPARC-meeting at RIKEN, 7-8, April, 2008 NUCLEON PARTONIC STRUCTURE 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 What is the nucleon partonic structure? theoretical base: QCD Transverse spin dependent distributions, Transverse Momentum Dependent(TMD) distributions Takahiro Iwata JPARC-meeting at RIKEN, 7-8, April, 2008 QUARK DISTRIBUTIONS Nucleon Parton number density Nucleon unpol. long. pol.trans. pol. unpol. long. pol. trans. pol. Quark Sivers helicity T-odd Boer- Mulders twist 2 JPARC-meeting at RIKEN, 7-8, April, 2008 QUARK DISTRIBUTION STUDY IN SIDIS Takahiro Iwata SIDIS In SIDIS, PDFs appear accompanied with fragmentation functions Transversity Collins fragmentation function Sivers PDF un-polarized fragmentation function Sivers PDF (TMD) Related to orbital angular momentum of quarks JPARC-meeting at RIKEN, 7-8, April, 2008Takahiro Iwata Advantage: NO NEED OF ANY FRAGMENTATION FUNCTIONS Drell-Yan is alternative way to study quark distributions Double polarized Drell-Yan direct extraction of TRANSVERSITY planned at GSI But, a big challenge experimentally QUARK DISTRIBUTION STUDY IN DY JPARC-meeting at RIKEN, 7-8, April, 2008Takahiro Iwata unpol. DY single polarized DY cos2 modulation relates to Boer-Mulders function FF free prediction Unpol. PDF Transversity Siverse function B.M. function QUARK DISTRIBUTION STUDY IN DY Collins, PL B536 (2002) 43 Takahiro IwataJPARC-meeting at RIKEN, 7-8, April, 2008 DY KINEMATICS lepton pair CM frame P 1,P 2 incoming hadrons nucleon spin vector q T :transvese momentum of virtual photon lepton plane hadron plane case VALENCE REGION probed in COMPASS Takahiro IwataJPARC-meeting at RIKEN, 7-8, April, 2008 UN-POLARIZED DRELL-YAN q T weighted angular distribution 1 st moment of the PDFs: Number densities (well known) Boer-Mulder for anti-q in Boer-Mulder for q in proton A.Sissakian et al., Phys. Rev. D72, (2005 ) unpolarized Drell-Yan : Takahiro IwataJPARC-meeting at RIKEN, 7-8, April, 2008 SINGLE SPIN ASYMMETRIES q T weighted SSA single polarized Drell-Yan : transversitySivers nucleon Spin vector trans. mom. of photon Takahiro IwataJPARC-meeting at RIKEN, 7-8, April, 2008 SINGLE SPIN ASYMMETRIES Boer-Mulder func. for transversity A.Sissakian et al., Phys. Rev. D72, (2005 ) number densities (well known) 1st moment of number density for Sivers func. number densities (well known) DRELL-YAN PROGRAM IN COMPASS DRELL-YAN PROGRAM IN COMPASS Takahiro IwataJPARC-meeting at RIKEN, 7-8, April, 2008 DY PROGRAM IN COMPASS Beam: 1x10 7 /s ( = 5x10 7 /spill) Intensity limited at least by radiation regulation at the EXP. hall Polarised proton target (NH 3 ) Spectrometer (the running spectrometer): Good hadron/electron/muon separation in 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) - Target: NH3 and L NH3 =15 cm x 2, ( NH3 : 0.85 g/cm 3 ) - PT material filling factor F f = Number of nucleon in NH 3 molecule: A NH3 =17 - beam intensity: I beam = 1 10 7 pions/s - N A = 6.0 10 23 mol -1 Luminosity: L = L NH3 N cell NH3 F f N A 1/A NH3 I beam =1.110 31 cm -2 s -1 - reconstruction efficiency (acceptance incl.) : A DY cross section on NH 3 : NH3 = N nucl p, where N nucl =17 -D spill = 5 s (duration of spill), N spill =4000 (number of spills per day), E sps = 80% (efficiency of the machine) - Duration of the Run 150 days: D RUN =150 R = L N nucl p A D spill N spill E SPS D RUN DY EVENT RATE Takahiro IwataJPARC-meeting at RIKEN, 7-8, April, 2008 150 days of running M ( + - ), GeV S, GeV 2, (E ) 100 (E GeV 78,5006, (E GeV 146,00022, (E GeV 175,00033,660 Cross section values were taken from AB_5 A.Bianconi generator cross-checked with PYTHIA data (A.Nagaytsev, Dubna), without J/ contribution STATISTICS Takahiro IwataJPARC-meeting at RIKEN, 7-8, April, 2008 Takahiro IwataJPARC-meeting at RIKEN, 7-8, April, 2008 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 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 studied by simulation & beam test POLARIZED TARGET FOR DRELL-YAN PROGRAM JPS meeting at Sapporo, September 22, 2007 Takahiro Iwata TARGET MATERIAL - beam (~ 10 7 particles/s) high polarization, high dilution factor, long relaxation time hadronic interactions with high probability secondary particles(multiplicity?) small spot size available ( x = y ~5mm) HEAT INPUT TRANSVERSELY POLARIZED target required NH3 POLARIZED TARGET FOR DY COMPASS PT operation: Polarization enhancement only in longitudinal spin mode (2.5T) Transverse spin mode given in frozen spin mode(