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CERN’s Potential for Spin-Flavour studies of the Nucleon Short term Medium term Long term

CERN’s Potential for Spin-Flavour studies of the Nucleon Short term Medium term Long term. Many slides based on CERN Workshop May 11-13, 2009 http://indico.cern.ch/conferenceDisplay.py?confId=51128. CERN’s DIS experiments. Long standing tradition @ CERN

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CERN’s Potential for Spin-Flavour studies of the Nucleon Short term Medium term Long term

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  1. CERN’s Potential for Spin-Flavour studies of the Nucleon • Short term • Medium term • Long term Many slides based on CERN Workshop May 11-13, 2009 http://indico.cern.ch/conferenceDisplay.py?confId=51128 GSI May 2009

  2. CERN’s DIS experiments • Long standing tradition @ CERN • North Area experiments at M2 muon beam line since late 1970s • EMC, BCDMS, NMC, SMC, COMPASS • Is there still a role to play for CERN in spin-flavour studies? • What can be improved, where are the limits? GSI May 2009

  3. M2 Muon beam line SPS proton beam: 1.4 1013/spill, 400 GeV/c Secondary hadron beams (, K, …): 2.108 /spill, 150-270 GeV/c Tertiary muon beam (80% pol): 2.108 /spill, 100-200 GeV/c (numbers for 4.8 s spill) LHC M2 CNGS GranSasso 732 kms SPS

  4. Experimental areas • ECN3 Exp Cavern • underground • EHN2 Exp Hall • surface building M2 • EHN1 Exp Hall • ~surface building • TCC2 target hall • underground

  5. Improvements COMPASS/SMC 2002-2006 w/o 2005 • higher beam intensity (5x) • DAQ (500 Hz -> 20 kHz) • dead time • target material (6LiD) g1d(x) 160 GeV 3 years 1992-4-5

  6. Short term: 2010 – 2011/2 Plans with exisiting COMPASS spectrometer (Completion of original muon part of proposal) • transverse target polarisation: • proton target (NH3), one year data taking • Collins & Sivers asymmetries and friends • longitudinal target polarisation: • proton target (NH3), one year data taking • g1P, g1ns, Bradamante d’Hose GSI May 2009

  7. COMPASS m filter 160 GeVμ ECal & HCal 50 m SM2 m filter RICH SM1 MWPC 6LiD Target Straws GEMs Drift chambers Micromegas Silicon SciFi 190 GeV p +/ -/ p/ K Hadron Spectroscopy 100-200 GeV m +/ - →

  8. Transverse polarisation (short term) h+ h- □ COMPASS 2010 proj. ○ COMPASS 2007 (part) ● HERMES Coll projected precision Siv Is Sivers non-zero for the proton?

  9. Longitudinal polarisation (short term) • ■ COMPASS proj. 2007 • * COMPASS proj. 2007 plus 1 year○ SMC data ■ COMPASS data ○ SMC data g1d(x) 160 GeV g1p(x)

  10. Longitudinal polarisation (short term) g1NS  2(g1p -g1d)non-singlet spin structure function • Precise shape determination at low x • More reliable extrapolation to x=0 • Reduced statistical and systematic errors in the test of the Bjorken sum rule (fundamental result of QCD)

  11. Longitudinal polarisation (short term) Flavourasymmetry of the polarised light sea QSM Meson cloud * COMPASS Projection with 1 additional year of proton HERMES 6

  12. Medium term: 2012/3 – 2015/6 (?) Modified COMPASS spectrometer • GPD DVCS and DVMP • 2.5 m liquid hydrogen target, 1 year • transversely polarised target, 1 year • BCA • Drell-Yan πp↑: • transversely polarised proton target, 2 years • Sivers/Boer-Mulders d’Hose Bradamante GSI May 2009

  13. Generalised Parton Distributions • Unified description of formfactors and parton distribution • Transverse imaging(nucleontomography) and to access the quark angularmomentum Impact parameter b Longitudinal momentum fraction x Tomographic parton images of the nucleon 8

  14. COMPASS GPD Programme ZEUS H1 COMPASS HERMES JLab • + and - beamwithopposite polarisation ±80% • 2.5m long LH2 targetL = 1032 cm-2 s-1 • Lumilimits Q2 to 8 GeV2upgrades welcome • ENC@FAIR withEp=15GeV, Ee=3GeV isequivalent to E = 100GeV Limit due toluminosity ? 9

  15. DVCS & BH interference DVCS known BH   GPD slow p p slow p small t small t   p d  |TDVCS|2 + |TBH|2 + interference term the three terms dominate in different kinematic regions 10

  16. Comparison BH and DVCS  μ’ * θ μ p  Eμ=160 GeV At Q2=2 GeV2 |t|=0.1 GeV2 x=0.01 x=0.04 x=0.1    BH dominates BH and DVCS at the same level DVCS dominates reference DVCS boosted by interferencestudy ofdDVCS/dt  Re TDVCS or Im TDVCS (not possible at JLab)

  17. DVCS + BH with + and - beam  μ’ * θ μ p  dσ(μpμp) = dσBH + dσDVCSunpol + PμdσDVCSpol + eμ aBHReTDVCS + eμ PμaBHImTDVCS • Beam Charge & Spin Difference DU,CS ()  d(+ ) -d(- ) • Beam Charge & Spin Sum SU,CS ()  d(+ ) +d(- )

  18. Transverse imaging 1<Q2<8 LOI CERN-SPSC-2009-003 SU,CS integrated, BH subtracted dDVCS/dt ~ exp(-B|t|) B(x) = b0 + 2 α’ ln(x0/x) FFS model: α’ =0.125 GeV-2

  19. Beam Charge and Spin Asym. DU,CS/SU,CS D.Mueller-hep-ph/0904.0458 fit on world data LOI CERN-SPSC-2009-003

  20. Proposal to study GPDs in 2 phases  d( +) -d( -) and Re(F1 H) DU,CS andIm(F1 H) SU,CS  d( +) +d( -) Phase 1: DVCS experiment in ~2012 to constrain GPD H with +, - beam + unpolarized long LH2 (proton) target d /dt transverse imaging Phase 2: DVCS experiment in ~2014 to constrainGPD E with + and transversely polarized NH3 (proton) target d(, S) - d(, S+π) Im(F2H– F1E)sin(- S) cos 

  21. Medium term: 2012/3 – 2015/6 (?) • Drell-Yan in π- p • transversely polarised proton target, 2 years • unpolarised liquid hydrogen target, optional Slides from Bradamante , Denisov, Quintans

  22. The Drell-Yan process in π- p

  23. The Drell-Yan process in π- p

  24. The Drell-Yan process in π- p

  25. Single Spin asymmetry COMPASS acceptance Anselmino et al. 2009 predictions Sizeable spin asymmetries are expected

  26. Drell-Yan: Projected results

  27. Drell-Yan: Radidation

  28. Further Drell-Yan measurements

  29. Anti-proton beam? In present M2 hadron beam ≤ 5 106p(due to 2x108 (p) limit on total beam flux for radio-protection) Secondary particle fluxes Apply Atherton formula for 0 mrad (approximative only for p  60 GeV/c). Obtain # particles per steradian per GeV/c and per 1012 interacting protons: Relative production rates (log) pbar fraction: a few % Preliminary rate estimates for RF separated antiproton beams L.Gatignon, 17-10-2006

  30. RF separatedp beam? First and very preliminary thoughts, guided by recent studies for P326 and studies for CKM by J.Doornbos/TRIUMF, http://trshare.triumf.ca/~trjd/rfbeam.ps.gz E.g. a system with two cavities: RF2 RF1 DUMP DUMP L Momentum selection Choose e.g. DFpp DF = 2p (L f / c) (b1-1 – b2-1) with b1-1 – b2-1 = (m12-m22)/2p2 At 100 GeV. With 2x1013 primary protons /10 s spill on the production target get ~ 3x108 total flux with purity about 50%, → antiproton flux ≈ 1.5 108ppp comparable to present p and p flux Preliminary rate estimates for RF separated antiproton beams From slide of L.Gatignon, 17-10-2006

  31. Long term: > 2018 CERN accelerator upgrade: new injectors from Ilias Efthymiopoulos (CERN-EN/MEF) GSI May 2009

  32. LHC Injector upgrade program • PS2 replaces PS • ~5 ÷ 50 GeV/c beams • 1.0×1014ppp • SPS Upgrade • Single injection form PS2  shorter cycles • The machine is upgraded and can handle the PS2 delivered intensity! ~2018

  33. PS2 integration (M. Benedict) • “Straight” H- inj. line SPL  PS2 avoiding large bending radii to minimise Lorentz stripping of H-. • Minimum length of inj. line TT10  PS2 for ions and protons from PS complex. • Minimum length HE line PS2  SPS. SPS PS2 to SPS PS2 PS2-SPL approval 2012 constr. 2013-2018 PS/LEIR to SPS / PS2 SPL to PS2 SPL PS Linac4 (2008/2014) PAC 2009 Vancouver PS2 Design Optimization, M.Benedikt 33

  34. Implications for SPS North Area Today • Imax (integrated) : 3.5×1013 ppp / 9.6s flat-top • instantaneous rate : 3.6×1012 pHz • Imax (instantaneous) = 5.0×1012 pHz • 2.4 × 1013 ppp / 4.8s flat-top Future • The foreseen intensity from PS2/SPSU (1.0 × 1014ppp) represents a factor 2.85increase in overall beam intensity • In reality ~10% less due to losses at SPS and extraction line • Note this is the total – intensity, i.e. for all targets that then is split, etc. Can the NA infrastructure accept the ×2.5 intensity increase and the shorter super-cycle (no CNGS, LHC? Is even higher intensity possible if requested for future experiments ? SFTPRO 3xCNGS LHC MD New Opportunities Workshop

  35. Implications for SPS North Area Beam cycles Today Future • The single injection from PS2 implies a gain up to ~10% in cycle length • e.g. 43.2s instead of 48.0s for the case of a 9.6s flat top • The 14.4s flat top, if technically possible, would correspond to 6.95×1012pHz, 40% more of today’s maximum instantaneous rate for the experiments , and a ×2.15 gain in duty cycle compared to today • Note: The MD cycle (and LHCs) are needed to maintain the average power in the magnets within limits New Opportunities Workshop

  36. Implications for SPS North Area Limitations – main issues Long flat-top: • average power to magnets and magnetic extraction septa Intensity increase: • Electrostatic septa: • beam losses and induced activation • temperature of the wires; sparks • Heating and deformation of ion-trap plates • Losses in beam splitters • Cooling of targets and TAX blocks : • Shielding in surface experimental areas (intensity, muons, dumps) • EHN1, and EHN2 experimental halls New Opportunities Workshop

  37. Experimental areas • ECN3 Exp Cavern • underground • EHN2 Exp Hall • surface building M2 • EHN1 Exp Hall • ~surface building • TCC2 target hall • underground

  38. Further possible improvements • Radiation: Underground experimental area • Increase of pion decay region, e.g. from 600 m to 1800 m would increase muon intensity by a factor ~3

  39. Further physics opportunities • LeHC • extracted beams from LHC • Neutrinos, CERN workshop in October 2009

  40. Comparison COMPASS FoM (w/o beam) eRHIC p-2 ~ 0.4, ENC similar

  41. Summary • CERN will remain a major player in spin flavour structure • The existing facilities are in the same ball park as ENC@Fair and eRHIC light • The biggest difference is the CMS energy ofeRHIC light, which will allow to access lowerx values. • The injector upgrade ~ 2018 will provide a major intensity increase, provided the experimental areas and transfer lines are upgraded. • More work is needed

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