1 / 22

Future Drell-Yan program of the COMPASS cllaboration

Future Drell-Yan program of the COMPASS cllaboration. Norihiro DOSHITA (Yamagata University) On behalf of the COMPASS collaboration. KEK theory center workshop on High-energy hadron physics with hadron beams January 6 - 8, 2010Seminar Hall, Building No.3, KEK, Tsukuba, Japan. Outline.

oriel
Download Presentation

Future Drell-Yan program of the COMPASS cllaboration

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. Future Drell-Yan program of the COMPASS cllaboration Norihiro DOSHITA (Yamagata University) On behalf of the COMPASS collaboration KEK theory center workshop on High-energy hadron physics with hadron beams January 6 - 8, 2010Seminar Hall, Building No.3, KEK, Tsukuba, Japan N. Doshita

  2. Outline • Access TMDs from (polarized) Drell-Yan process • Experimental setup - Spectrometer - Polarized target - Statistics estimations • Beam test in 2007 – 2009 • Summary N. Doshita

  3. In the COMPASS experiment muon program (2002 ~ 2007) Deeply Inelastic Scattering with polarized muon and polarized nucleon target quark nucleon Longitudinal polarized target - gluon spin distribution: G - quark helicity distribution : q(x) Transversal polarized target - quark transversity distribution : Tq(x) - Sivers function : f1T Since SMC experiment  - l+ Quark orbital angular momentum * Polarized Drell-Yan program (2012 ~ ) with pion beam and transversally polarized target l- p Drell-Yan process N. Doshita

  4. Motivation - Boer-Mulders function Unpolarized Drell-Yan Phys.Lett. B639 (2006) 494 The cos2 angular dependent weighted cross section of (p-,p) at valence region (xp> 0.1) : Boer-Mulders functions of the valence and sea quarks inside the pion respectively : Boer-Mulders functions of the quark flavor inside the proton Flavor separation: The ratio of the weighted cross sections of (p-, p) and (p-, D) (p-, p) and (p+,p) N. Doshita

  5. Motivation - Transversity and Sivers function SIDIS many components of transverse target spin dependent azimuthal modulations (polarized beam with transversal polarized target) Uncertainty of Fragmentation Function Polarized Drell-Yan (single spin DY asymmetries) FF free Unpol. PDF prediction N. Doshita

  6. Double polarized Drell-Yan: direct access to Transversity With polarized antiproton beam and polarized proton target M.Nekipelov -> PAX Feasibility study is underway, polarized antiprotons(>20%) - not a trivial issue N. Doshita

  7. J/Y – Drell-Yan duality • J/Y – DY duality  close analogy between Drell-Yan and J/Y production mechanism: • Occurs when the gluon-gluon fusion mechanism of the J/Y production is dominated by the quark-quark fusion mechanism • We can expect that the duality is valid in the COMPASS kinematic range • Key issue for the applicability of the J/Y signal for the study of hadron spin structure • J/Y production mechanism by itself is an important issue  J/ substitution N. Doshita

  8. The COMPASS spectrometer Large angular acceptance spectrometer Various secondary beams with the intensity up to 6x107 particles/s A detection system designed to stand relatively high particle fluxes The dedicated muon trigger system Hadron absorber is needed Polarized target and hadron absorber p±,m± N. Doshita

  9. COMPASS polarized solid target system Large acceptance COMPASS Magnet Cooling power Transverse polarization mK • Frozen spin target at 0.6 T dipole magnet • (after polarizing at 2.5 T solenoid) Cooling power • Many secondly particels – nuclear interaction • 2 mW heat input expected • with 6 x 107 pions/s • 5 mW cooling power at 70mK mmol/sec Target cell • Target area: 130 cm long with < ±30 ppm • 10 cm gap • 3 cells (27.5, 55, 27.5cm long) • 20 cm gap • 2 cells (50, 50 cm long) beam 180mrad N. Doshita

  10. Proton target materials Figure of Merit f : dilution factor  : density Ff : packing factor • Normalized by • H-butanol • Magnetic field 2.5T • Relaxation time • NH3 4000h at 60 mK and 0.6T • - If 7LiH reach 90%, PTFoM is 2.1. * J.Ball,NIM.A526(2004)7. N. Doshita

  11. Deuteron target materials Figure of Merit f : dilution factor  : density Ff : packing factor • Normalized by ND3 . • Magnetic field 2.5T • Relaxation time • 6LiD 2000h at 0.42T and 60 mK. ** S.T.Goertzetal, NIM.A526(2004)43. N. Doshita

  12. Signal and background Dimuon mass spectrum (NA50) • 2 backgrounds sources • Physics background • D,D and J/y decays to m+m-X • Combinatorial background • p and K decaying to mn Drell-Yan J/y, y’ Open charm Empty target Comb. bkg Better region to study Drell-Yan is 4 < M GeV/c2. N. Doshita

  13. Some indications for statistics • High luminosity (DY Cross Section is a fractions of nanobarns) and large angular acceptance, better pion or antiproton beams (valence anti-quark) • Sufficiently high energy to access ‘safe’ of background free Mll range ( 4 GeV/c < Mll < 9 GeV/c) • Good acceptance in the valence quark range xB > 0.1 and kinematic range: τ = xAxB = M2/s > 0.1 • Good figure of merit (PTFoM), which can be represented as a product of the luminosity and beam (target) polarization (dilution factor) (PTFoM~ L × Pbeam (f)) N. Doshita

  14. Cross section and acceptance COMPASS acceptance is in the valence quarks regions (x > 0.1). This is also the best region to measure the spin asymmeties, as expected from theory predictions. N. Doshita

  15. Expected statistical error for Sivers asymmetry • With a beam intensity of 6 x 107 particles/s, a luminosity of 1.7 x 1033 /cm2s can be obtained. • Assuming 2 years of data-taking, more than 200k DY events in the region 4 < M < 9 GeV/c2. Predictions of Sivers asymmetry in the COMPASS phase space. • Solid and dashed: Etremov et. Al, PLB612(2005)233. • Dot-dashed; Collins et al, PRD73(2006)014021. • Solid, dot-dased; Ansemino et al, PRD79(2009)054010. • Bixes; Blanconi et al, PRD73(2006)114002. • Short-dashed; Bacchetta et al; PRD78(2008)074010. XF N. Doshita

  16. Beam test in 2007 Feasibility test at COMPASS N. Doshita

  17. Drell – Yan Beam test 2009 • Data taking: Nov 19 - 23 • Beam : 190 GeV negative pion • Target : 40+40cm CH2 target with 5cm diameter (100% interaction length) • Nominal intensity: 7-9 x 10^7 / spill • Total data : 4800 good spills • High intensity beam test was also done. (1.5 x 10^8 / spill) • Radiation level : low (< 0.5 uSv/h ) N. Doshita

  18. DY Feasibility@COMPASS Beam Test 2009 (with hadron absorber I) target

  19. DY Feasibility@COMPASS Beam Test 2009 (with hadron absorber III) Top view target N. Doshita

  20. Some results of 2009 DY beam test I:radio-protection issues and tracking detectors occupancies • RP - the detected radiation level is factor 6 lower than allowed one (3 uSv), in a good agreement with simulations done by COMPASS and CERN RP (pion beam intensity ~8x10^7 pions per spill (10 seconds)) • The tracking detectors occupancy downstream of hadron absorber is factor 10 lower compare to the normal muon running conditions 20 N. Doshita

  21. Some results of 2009 DY beam test II:J/Psi – monitoring signal for DY • Very clean J/Psi signal observed • Combinatorial background for such a beam intensity seem absent in high dimuon mass range • The J/Psi production/registration/reconstruction rate is high even with not optimised hadron absorber (number of radiation/interaction length ratio) and very raw reconstruction procedure (no hadron absorber in the standard COMPASS reconstruction program). VERYPRELIMINARY N. Doshita

  22. summary • COMPASS will be able to perform several combinations of beams (p-, p+, p(?)) and targets (p , D ) for Drell-Yan measurement. • We will perform the first measurement with p- beam and transversal polarized p target. • The expected accuracy after 2 years data taking is enough to provide unique information of hadron structure and of transverse momentum PDFs. N. Doshita

More Related