1 / 37

COMPASS PLANS

COMPASS PLANS. Stephane Platchkov I nstitut de R echerche sur les lois F ondamentales de l’ U nivers CEA/IRFU, Saclay , France (for the COMPASS Collaboration). EIC workshop Stony Brook, June 24- 27, 2014. COMPASS – a fixed target experiment. A very versatile setup

nerea-hale
Download Presentation

COMPASS PLANS

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. COMPASS PLANS Stephane Platchkov Institut de Recherchesur les loisFondamentales de l’Univers CEA/IRFU, Saclay, France (for the COMPASS Collaboration) EIC workshop Stony Brook, June 24-27, 2014

  2. COMPASS – a fixed target experiment • A very versatile setup • Several beams available: µ+, µ-, h+, h-, e-=> Several physics goals Energy: 100 – 200 GeV Intensity: up to 109/spill Large acceptance, PID detectors Several particles in the final state Large (1.2 m) polarized target 50 m “Minor” changes to the setup – switch between various physics programs EIC 2014

  3. COMPASS – a fixed target experiment • A very versatile setup • Several beams available: µ+, µ-, h+, h-, e- => Several physics goals Measurements with muon beams • Gluon polarization • Spin-flavor decomposition • Transversity • Transv. Mom. Distributions Measurements with hadron beams • Pion polarizability • Light meson spectroscopy • Baryon spectroscopy • Search for hybrids COMPASS - I (2002 – 2011) COMPASS - II (2012, 2015 – 2017/2018) • DVCS and HEMP • Unpolarized SIDIS and TMDs • Drell-Yan studies • Pion and Kaonpolarizabilities EIC 2014

  4. Nucleon structure studies – physics goals from Bacchetta from Bacchetta PDF (x) TMD (x,kT) GPD (x,bT) Drell-Yan EIC 2014

  5. DVCS and HEMP studies EIC 2014

  6. Beams 100 – 200 GeV Beam polarization: ~80% Both m+ and m- beams x domain: ≈ 0.01 – 0.1 Q2 domain: 1 to 10 (GeV/c)2 Luminosity: 1032 cm-2s-1 (with a 2.5 m long LH2 target) DVCScharacteristics in COMPASS + EIC Detect both outgoing photon and recoiling proton EIC 2014

  7. DVCS and BH cross section for µ+ and µ- Cross section for µp -> µpγ : • COMPASS beams: opposite charge/spin • Charge-and-Spin Sum: • Charge-and-Spin Difference • small for COMPASS DVCS BH Access both Re(H) and Im(H) by measuring the Sum and the Difference EIC 2014

  8. DVCS – SUM of m+ and m- cross sections Expected statistics in 2 x 140 days of data taking Goal: transverse size of the nucleon as a function of xB - Nucleon “tomography” - EIC 2014

  9. Beam Charge and Spin Difference Expected statistics in 2 x 140 days of data taking Kroll, Moutarde, Sabatié, EPJC 73(2013)2278 EIC 2014

  10. DVCS – the COMPASS xBregions – SIMULATION 0.005 < xB <0.01 0.01 < xB < 0.03 xB > 0.03 DVCS BH DVCS BH Large relative amplitude variation as a function of x EIC 2014

  11. Test run – 4 days with a 40 cm long H2 target DVCS – the COMPASS xBregions – REAL DATA 2009 data 278 134 54 DVCS BH dominance Interference DVCS dominance Successful feasibility measurement EIC 2014

  12. DVCS run – main new equipment ECAL2 ECAL0 ECAL1 50 m 4.0 m longTime-Of-Flight detector: 24 inner and 24 outer slabs 2x2 m2 electromagnetic calorimeter, ECAL0 2.5 m long LH target EIC 2014

  13. 2012 DVCS setup – 4 weeks data taking ECAL2 Partially ready ECAL0 ECAL1 Full scale recoil proton detector Liquid H2 target EIC 2014

  14. Transverse size of the nucleon Test data taking in 2012 – 4 weeks 2012 data: expected uncertainty Data analysis is underway EIC 2014

  15. Semi-inclusive unpolarized DIS • Features • Pure hydrogen target, 2.4 m long • High-performance particle identification for p+,p-,p0,K+,K-,K0 etc… • Measurements of: • Multiplicities Input to global FF analysis • Strange quark pPDF down to x=0.004 Phys. Rev. D 89 (2014) 097101 1 week of beam will s(x) continue to raise? EIC 2014

  16. Beyond GPD H • Hard Exclusive Meson production • Vector mesons: sensitive to H, E • allows for flavour separation • Present studies at COMPASS : • Transversely polarized target • No recoil proton detection (From transversity data: 2007/2010) • First example: exclusive r production EIC 2014

  17. Exclusive r0 production • Measurement: μ+ p  μ’ + 0+p +- COMPASS: PLB 731 (2014) 19 NPB 865 (2012) 1 First possible indication for a non-vanishing HT Access to different E and H combinations Analysis of wongoing EIC 2014

  18. Distant future (beyond 2018) • DVCS and HEMP on a transversely polarized target • 2 years of data, NH3 target, 160 GeV, global efficiency ~10% Main challenge: development of dedicated superconducting magnet Planned proposal/addendum EIC 2014

  19. Overview of past/planned GPD experiments EIC 2014

  20. Drell-Yan studies EIC 2014

  21. . COMPASS setup advantages Beam energy: 100 – 200 GeV Hadron (pion) beam Transversely polarized NH3 target Large muon angular acceptance With a negative pion beam: u/u annihilation COMPASS acceptance (MC simulation) Dominated by valence quarks (x ≥ 0.1) Polarized Drell-Yan measurements Drell and Yan, PRL 25 (1970), 316, 902. COMPASS is an ideal place for DY studies EIC 2014

  22. DY (polarized) cross section expansion Tung-Mow Yan (SLAC, 1998): “The process (1970) has been so well understood that it has become a powerful tool for precision measurements and new physics” • Full formalism for two spin ½ hadrons • COMPASS: access 4 TMDs: • Boer-Mulders, Sivers, Pretzelosity, Transversity • Access 4 TMDs – asymmetry modulations: Arnold, Metz and Schlegel, Phys. Rev. D79 (2009) 034005. Boer-Mulders Sivers Pretzelosity Transversity Worm-Gear All four TMDs are also measured in SIDIS EIC 2014

  23. TMDs in Drell-Yan and SIDIS • SIDIS vs TMD • SIDIS: TMD and FF • Drell-Yan: two TMDs • Factorization • TMDs (unlike PDFs) can be process dependent (“non-universality”) • Opposite sign in SIDIS and DY processes: Collins, Soper, Sterman, Adv. Ser. High En Phys. 5, 1988. Crucial test of the QCD factorization approach EIC 2014

  24. Sivers asymmetry (SIDIS) • Compass data on a proton target • pions • kaons COMPASS data: PLB 692 (2010) 240 PLB 717 (2012) 383 + preliminary Hermes data: PRL 103 (2009) 152002 EIC 2014

  25. Drell-Yan acceptances (COMPASS vs E615) 0.04 E615 (1989) 0.4 COMPASS (2014) An order of magnitude improvement EIC 2014

  26. SIDIS vs Drell-Yan (x - Q2) regions Kinematical overlap between SIDIS and Drell-Yan EIC 2014

  27. COMPASS Drell-Yan setup • Upgrade of the spectrometer • Beam telescope (Sci-Fi) • Thick hadron absorber/beam dump • Vertex detector • Polarized target moved 2.2 m upstream EIC 2014

  28. COMPASS Drell-Yan setup • Small cross sections – high intensity h beam (~109/spill of 10 sec) • Possible use of thin nuclear targets (inside the absorber) pion beam 190 GeV • Nominal COMPASS setup (minor modifications) • Dimuon trigger system Polarized Target • Hadron absorber: Tungsten, Alumina and Stainless steel EIC 2014

  29. Drell-Yan – test data taking • Test setup (3 days in 2009) • 190 GeV negative pion beam, I ≤ 1.5x107/s (instead of 108/s) • “poor-man” hadron absorber ( concrete and steel) • two polyethylene target cells • preliminaryDY trigger • Results • Count rate confirmed • Mass resolution as expected • Good vertex resolution • Low background at high masses EIC 2014

  30. Expected statistical accuracy • Assumptions: • Ibeam = 108p/s, L = 2.3x1033, P=90%, f = 0.22, t = 140 days, • spill length = 10 s, every 34 s • ~ 2000 DY events/day in the mass region 4 < Mµµ < 9 GeV/c2 • J/Ψ cross section: about 50 times larger Boer-Mulders Sivers Pretzelosity Transversity EIC 2014

  31. Polarized Drell-Yan – expected results Sivers Boer-Mulders 140 days of data 6.108pions/spill 2 x 55 cm NH3 target 4 < Mmm< 9 GeV Pretzelosity Transversity EIC 2014

  32. DY on nuclear targets flavour-dependent EMC effect Further Drell-Yan studies Dutta et al., PRC83:042201,2011 First glimpse from the 2015 data EIC 2014

  33. Drell-Yan: further possibilities • Medium term • DY on nuclear targets • Flavour dependent EMC, Violation of the Lam-Tung relation • Polarized deuteron ( 6LiD) target • Flavour separated TMDs • Long term • RF separated K- and p beams • Recall: at 190 GeV: p-/K-/p = 96.5%/2.5%/1% • Aim at 1 to 2 orders of magnitude improvement for K- and p EIC 2014

  34. COMPASS OUTLOOK • 2014 • Preparation for DY run • Refurbished PT magnet, PT installation, hadron absorber • 2 months of data taking (October-December) • 2015 • Drell - Yan data taking (1 “year” ≈ 140 days) • End 2015, beg. 2016 • Removal of PT, Installation of LH target, CAMERA, ECAL0 • 2016/2017 • DVCS data taking (2 “years” ≈ 2x140 days) • 2018 and beyond Long Shutdown 2 • Extensions of DY and DVCS programs (definition underway) EIC 2014

  35. The End EIC 2014

  36. Exclusive r0production • Measurement: μ + p  μ’ + 0+p +- 5 single-spin (UT) asymmetries 3 double-spin (LT) asymmetries Curves: Goloskokov and Kroll, EPJ C74(2014)2725 Data: Compass, PLB, 731(2014)19. EIC 2014

  37. Boer-Mulders asymmetry (SIDIS) • Compass data on deuteron (6LiD) • Significantly different from zero • Larger for negative hadrons • Dependence on all three variables: x, z, pT COMPASS preprint, hep-ex:1401.6284 also HERMES: PRD 87 (2013)012010. EIC 2014

More Related