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%) ＮＨ ３ ／ 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 =1.1×10 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(<100mK, B~0.6T)  Need long relaxation time ; low temperatures essential TARGET SIZE 2 target cells, 20~30cm long increasing temperature decreasing relaxation time local temperature increase Limit beam intensity Takahiro IwataJPARC-meeting at RIKEN, 7-8, April, 2008

mmol/sec mK measured cooling power Q total = Nm · (  m ·  +  He · (1 -  )) · 2L · E MIP ·  beam removed by the dilution refrigerator NmNm   L E MIP  beam : Multiplicity=3 : density : Packing factor : length of single cell =20cm : 2 MeV · cm 2 /g : Beam intensity 5 mW at 75mK Q total = 0.6mW TOTAL HEAT INPUT V.S. COOLING POWER 3 He flow rate (mmol/sec) THE REFRIGERATOR HAS SUFFICIENT COOLING POWER rough estimation Takahiro IwataJPARC-meeting at RIKEN, 7-8, April, 2008

should be below 100 mK. 1 x 10 7 /s. BEAM SPOT SIZE V.S. TEMPERATURE ( )cm configuration Takahiro IwataJPARC-meeting at RIKEN, 7-8, April, 2008

Gaussian beam  x =  y = 0.5 cm z(cm) GeV/cm 3 per primary targets cells(NH 3 ) done by H. Vincke and E. Feldbaumer  3cm beam spot beam Cavity #1 Liquid He ENERGY DEPOSITION FROM SIMULATION 190 GeV   Simulation code: FLUKA cell configuration: ( )cm Cavity #2Cavity #3  E~4.0 x GeV  E~4.9 x GeV Total heat input : ~0.4mW Takahiro IwataJPARC-meeting at RIKEN, 7-8, April, 2008

BEAM TEST FOR DY PROGRAM JPS meeting at Sapporo, September 22, 2007 Takahiro Iwata

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 2×10 7 /spill  L ~10 31 cm -2 s -1 ( ~ eq. to 10 8 /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 DRELL-YAN BEAM TEST Takahiro IwataJPARC-meeting at RIKEN, 7-8, April, 2008

1.0 uSv/h0.5 uSv/h 0.3 uSv/h 4.0 uSv/h 1.3 uSv/h 1.0 uSv/h 6.3 uSv/h No (additional) activation of beam line components was found 2.2×10 7 pions per spill (supercycle time 20.4s) dose rate below the limit (15 uSv/h) Control rooms Beam Target Takahiro IwataJPARC-meeting at RIKEN, 7-8, April, 2008 RADIATION CONDITON

@ High intensity ( 2.2×10 7 /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 Takahiro IwataJPARC-meeting at RIKEN, 7-8, April, 2008 SPECTROMETER CONDITON

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

magnet 2 x 10 7  /spill  1 spill = ~ 5 sec Takahiro IwataJPARC-meeting at RIKEN, 7-8, April, 2008 PT BEHAVIOR WITH PION BEAM NOTE: ON-beam temperatures do not show the real temperatures of the target, but they are sensitive to the beam intensity. 1x 10 7  /spill Beam tuning TEMPERATURE NO DEPOLARIZATION SEEN as expected Target spin maintained at 1T in longitudinal mode The behavior is compatible with that for the muon 8 /spill)

Takahiro IwataJPARC-meeting at RIKEN, 7-8, April, 2008 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.

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

JPARC-meeting at RIKEN, 7-8, April, 2008 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

Takahiro IwataJPARC-meeting at RIKEN, 7-8, April, 2008 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.

Takahiro IwataJPARC-meeting at RIKEN, 7-8, April, 2008 BACKUP SLIDES

5 x 10 7 muons/spill1 x 10 7 pions/spill Multiplicity ~ 5 with cm long Multiplicity measurement by temperature sensors 5 x 10 7 muons/spill 2 x 10 8 muons/spill Takahiro IwataJPARC-meeting at RIKEN, 7-8, April, 2008

Takahiro IwataJPARC-meeting at RIKEN, 7-8, April, GeV  - beam (S=375 GeV 2 ) 3.5 GeV <= M  <= 9.0 GeV ACCEPTANCE