1 / 42

Polarized DIS with Future Polarized Colliders

Polarized DIS with Future Polarized Colliders. Abhay Deshpande R IKEN B NL R esearch C enter (RBRC). Precision Lepton-Nucleon Scattering: HERA III Workshop Munich, December 18 th , 2002. RIKEN BNL RESEARCH CENTER. Overview.

chin
Download Presentation

Polarized DIS with Future Polarized Colliders

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. Polarized DIS with Future Polarized Colliders Abhay Deshpande RIKEN BNL Research Center (RBRC) Precision Lepton-Nucleon Scattering: HERA III Workshop Munich, December 18th, 2002 RIKEN BNL RESEARCH CENTER

  2. Overview • Introduction to different proposals under consideration for polarized DIS • Physics opportunities with: -- Polarized HERA, Electron Ion Collider (EIC) at BNL -- Tesla*HERA (THERA) + TESLA-N/ELFE@DESY • Status of Polarized Colliders at BNL -- Status and comments on EIC -- Status of polarized proton beam acceleration & collisions at BNL • Summary Physics Opportunities at Future Polarized Colliders

  3. Deep Inelastic Scattering • Observe scattered electron/muon & hadrons in current jets • Observe spectator or remnant jet Physics Opportunities at Future Polarized Colliders

  4. Why Collider in the Future? • Past polarized DIS experiments: MOSTLY FIXED TARGET • Collider has distinct advantages --- Confirmed at HERA • Better angular separation between scattered lepton & nuclear fragments  Better resolution of electromagnetic probe  Recognition of rapidity gap events (recent diffractive physics) • Better measurement of nuclear fragments • Higher center of mass (CoM) energies reachable • Tricky integration of beam pipe – interaction region -- detector Physics Opportunities at Future Polarized Colliders

  5. Projects Under Consideration • Pol. HERA needs polarized protons (Siberian Snakes, polarimeters etc.), Use existing detectors(?) • EIC needs a polarized electron accelerator facility at RHIC & a new detector • THERA & TESLA-N & ELFE need TESLA and polarized protons in HERA & a new detector What Physics?  Luminosity? CM Energy? Physics Opportunities at Future Polarized Colliders

  6. Kinematic Coverage ELFE: Q2max~ 102 GeV2 xmin~ 10-2 (1 GeV2) TESLA-N: Q2max~ 103 GeV2 xmin ~ 10-3 (1 GeV2) EIC: Q2max~ 104 GeV2 xmin ~ 10-4 (1 GeV2) HERA: Q2max~ 105 GeV2 xmin~ 10-5 (1 GeV2) THERA: Q2max~ 106 GeV2 xmin ~ 10-6 (1 GeV2) 20-100 GeV EIC overlaps with the fixed target experiments because of the changeable beam energies Physics Opportunities at Future Polarized Colliders

  7. Luminosity Vs. Center of Mass EIC has variable: -- beam energies -- polarized light nuclear species  100 times HERA luminosity  Collisions 2010(?) HERA has: -- 3 times larger CM  Collisions 2007(?) TESLA-N/THERA -- Need the DESY LC -- Low/High CM -- High/Low Luminosity  Collisions 2015(?) TESLA-N THERA Physics Opportunities at Future Polarized Colliders

  8. Scientific Frontiers: Future DIS Experiments • Nucleon Structure: polarized & unpolarized e-p/n scattering -- Role of quarks and gluons in the nucleon -- Unpolarized quark & gluon distributions -- Spin structure: polarized quark & gluon distributions -- Correlation between partons  hard exclusive processes leading to Generalized Parton Distributions (GPD’s) • Nuclear structure: unpolarized e-A scattering -- Role of quarks and gluons in nuclei -- e-p vs. e-A physics in comparison • Hadronization in nucleons and nuclei & effect of nuclear media -- How do partons knocked out of nucleon in DIS evolve in to colorless hadrons? • Partonic matter under extreme conditions -- e-A vs. e-p scattering; study as a function of A EIC e-A Physics Unpolarized Low x Issues: A. Caldwell Physics Opportunities at Future Polarized Colliders

  9. All of them at EIC & Pol. HERA Some at TESLA-N/ELFE Polarized DIS at Future Facilities • Spin structure functions g1 (p,n) at low x, high precision -- g1(p-n): Bjorken Spin sum rule better than 1% accuracy • Polarized gluon distribution function DG(x,Q2) -- at least three different experimental methods • Precision measurement of aS(Q2) from g1 scaling violations • Polarized structure function of the photon from photo-production • Electroweak structure function g5 via W+/- production • Flavor separation of PDFs through semi-inclusive DIS • Deeply Virtual Compton Scattering (DVCS)  Gerneralized Parton Distributions (GPDs) • Transversity • Drell-Hern-Gerasimov spin sum rule test at high n • Target/Current fragmentation studies • … etc….  DESY-PROC-1999-03 & EIC White-Paper BNL-Report-68933 (Feb.2002) Physics Opportunities at Future Polarized Colliders

  10. A. D. & V. W. Hughes EIC WS at Yale’00 Spin structure function g1 at low x Polarized HERA Polarized EIC ~5-7 days of data 3 years of data Studies included statistical error & detector smearing to confirm that asymmetries are measurable. No present or future approved experiment will be able to make this measurement Physics Opportunities at Future Polarized Colliders

  11. Polarized Gluon Measurements • This is the hottest of the experimental measurements being pursued at various experimental facilities: -- HERMES/DESY, COMPASS/CERN, E159/E160 at SLAC -- Low scales poses a potential problem for interpretation -- TESLA-N? -- RHIC Spin (polarized p-p) -- Issues of non-DIS scattering • Deep Inelastic Scattering kinematics of EIC/HERA -- Scaling violations (pQCD analysis at NLO) of g1 (TESLA-N) -- (2+1) jet production in photon-gluon-fusion process -- 2-high pT hadron production in PGF (TESLA-N) • Photo-production (real photon) kinematics at EIC/HERA -- Single and di-jet production in PGF -- Open charm production in PGF Physics Opportunities at Future Polarized Colliders

  12. A. D., V. W. Hughes & J. Lichtenstadt EIC WS, Yale’00 DG from Scaling Violations of g1 • World data (today) allows a NLO pQCD fit to the scaling violations in g1 resulting in the polarized gluon distribution and its first moment. • SM collaboration, B. Adeva et al. PRD (1998) 112002 DG = 1.0 +/- 1.0 (stat) +/- 0.4 (exp. Syst.) +/- 1.5 (theory) • Theory uncertainty dominated by the lack of knowledge of the shape of the PDFs in unmeasured low x region where EIC data will play a crucial role. • With approx. 1 week of EIC statistical and theoretical uncertainties can be reduced by a factor of 3-5 -- coupled to better low x knowledge of spin structure function -- less sensitivity on factorization & re-normalization scale variations in fits as new data at low x is acquired See J. Lichtenstadt’s talk in this meeting Physics Opportunities at Future Polarized Colliders

  13. Photon Gluon Fusion at EIC • “Direct” determination of DG -- Di-Jet events -- High pT hadrons • High Sqrt(s) at EIC & Pol. HERA -- no theoretical ambiguities in interpretation of data • Both methods tried at HERA in un-polarized gluon determination & both are successful! -- NLO calculations exist -- H1 and ZEUS results -- Consistent with scaling violation F2 results on G Signal: PGF Background QCD Compton Physics Opportunities at Future Polarized Colliders

  14. G. Radel, A. De Roeck, EIC WS, Yale’00 Di-Jet events Analysis at NLO At Electron Ion Collider: 4+ fb-1/yr At HERA: 150 pb-1/yr • Statistical accuracies shown for at 2 EIC luminosities and 1 pol. HERA luminosity • Detector smearing effects considered • Analysis performed at next to leading order • Will easily differentiate amongst different DG scenarios • Uncertainty in the first moment of DG will be improved by factors of 3 • If combined with g1 NLO analysis effective improvement is even more • EIC will give an absolute uncertainty of about 3-5% in DG J. Lichtenstadt, A.D. & V. Hughes, EIC WS, Yale’00 Physics Opportunities at Future Polarized Colliders

  15. G. Radel & A. De Roeck, EIC WS, BNL’02 Di-Jet World Data for DG/G EIC Di-Jet DATA 2fb-1 EIC: Good precision Constrains shape of DG(x) HERA: Lower x access Polarization in HERA much more difficult than RHIC(?)  D. Barber’s talk tomorrow HERA Di-Jet Data 500 pb-1 Physics Opportunities at Future Polarized Colliders

  16. Polarized PDFs of the Photons Direct Photon Resolved Photon • Photo-production studies with single and di-jet • Photon Gluon Fusion or Gluon Gluon Fusion (Photon resolves in to its partonic contents) • Resolved photon asymmetries result in measurements of spin structure of the photon • Asymmetries sensitive to gluon polarization as well… but we will consider the gluon polarization “a known” quantity! Physics Opportunities at Future Polarized Colliders

  17. M. Stratmann & W. Vogelsang, EIC WS, BNL ‘01 PDFs of polarized photon at EIC • Stat. Accuracy estimated for 1 fb-1 running (1 month at EIC including 50% inefficiencies of detector) • Single and double jet asymmetries • ZEUS acceptance • Will resolve photon’s partonic spin contents Direct Photon Resolved Photon Physics Opportunities at Future Polarized Colliders

  18. M. Stratmann & W. Vogelsang,EIC WS, Yale’00 & Pol. HERA WS, DESY’99 Photon Structure Function at HERA/EIC EIC 85 pb-1/day HERA 150 pb-1/yr Physics Opportunities at Future Polarized Colliders

  19. Parity Violating Structure Function g5 • This is also a test • Experimental signature is a huge • asymmetry in detector (neutrino) • Unique measurement • Unpolarized xF3 measurements • at HERA in progress • Will access heavy quark • distribution in polarized DIS For HERA & EIC Physics Opportunities at Future Polarized Colliders

  20. J. Contreras & A. De Roeck, Pol. HERA WS, DESY’99 & EIC WS BNL’01 Measurement Accuracy PV g5 at EIC Assumes: for EIC (LEFT FIGURE) • Input GS Pol. PDfs • xF3 measured by then • 2 fb-1 luminosity • Makes the case for e+/e- beam facility • Assumes for HERA (RIGHT FIGURE) • Input GS polarized PDFs • xF3 is measured by then • 1 fb-1 luminosity • Both e+/- beams Physics Opportunities at Future Polarized Colliders

  21. S. Bass, A. De Roeck & A. Deshpande, EIC WS, Yale’00 Drell Hern Gerasimov Spin Sum Rule • DHG Sum rule: • At EIC n range: GeV  few TeV • AT HERA : 10s of GeV  10s TeV • Although contribution from to the this sum rule is small, the high n behavior is completely unknown and hence theoretically biased in any present measurements at: Jefferson Lab., MAMI, BNL • Inclusive Photo-production • measurement • Using electron tagger in • EIC • -- Q2 ~ 10-6 10-2 GeV2 • -- Sqrt(s) ~ 25  85 GeV • HERA: • -- Q2 ~ 10-6 10-3 GeV2 • -- Sqrt(s) ~ 40  250 GeV Physics Opportunities at Future Polarized Colliders

  22. S. Bass & A. De Roeck DGH Spin Sum Rule Contribution from EIC/eRHIC and HERA (1)+(2) =0.5 (1)+(4) (1)+(2)=-0.5 (1)+(3) Physics Opportunities at Future Polarized Colliders

  23. HERA, TESLA-N, ELFE E. Kinney & U. Stoesslein, EPIC WS, MIT’01 Strange Quark Distributions at EIC • After measuring u & d quark polarized distributions…. Turn to s quark (polarized & otherwise) • Detector with good Particle ID: pion/kaon separation • Upper Left: statistical errors for kaon related asymmetries shown with A1 inclusive • Left: Accuracy of strange quark distribution function measurements possible with EIC and HERMES (2003-05) and some theoretical curves on expectations. Physics Opportunities at Future Polarized Colliders

  24. M. G. Perdekamp, EIC WS, Yale’00 TESLA-N, ELFE in HERMES Kinematics Transversity EIC with 80 pb-1~ 1 day • Measure helicity flip amplitude = d(x,Q2) quark transversity • Does not mix with gluon distributions in its QCD evolution • Measure single spin asymmetries (DIS + p0) • Large acceptance desired |eta|<3.5 Collins/fragmentation function being measured by: RBRC from e+e- at B-factor at BELLE  Expect preliminary results in ’03 Physics Opportunities at Future Polarized Colliders

  25. ELFE EIC DVCS/Vector Meson Production • Hard Exclusive DIS process • g (default) but also vector mesons possible • Remove a parton & put another back in!  Microsurgery of Baryons! • Claim: Possible access to skewed or off forward PDFs? • Polarized structure: Access to quark orbital angular momentum? • On going theoretical debate… experimental effort just beginning • at HERA, Jlab… For ELFE this is the principle motivation Physics Opportunities at Future Polarized Colliders

  26. A. Sandacz, EIC WS, BNL’02 D. Hassel, R. Milner Deeply Virtual Compton Scattering DVCS has already been seen at HERA… New Detector Techniques at EIC Roman pots a la PP2PP at RHIC DVCS study for EIC (preliminary) 10 x 250 GeV Q2> 1 GeV2 20<W<95 GeV 0.1<|t|<1.0 GeV2 Full curve: all events Dashed curve: accepted events Q2>1 GeV2: 50K events/fb-1 Physics Opportunities at Future Polarized Colliders

  27. W.-D. Nowak, Int. WS on Hadron Structure, Trieste, Feb.2002 Future Fixed Target DIS at DESY • TESLA-N -- Use one (positron) arm of TESLA for polarized fixed target experiment -- Beam energy variable 30-250 GeV -- Large Q2 range compared to present fixed target experiments -- PHYSICS: Transversity distributions, Polarized Gluon Distribution • Run in parallel with the ee collider experiments • Will need: • 1. Polarized source and injector • 2. Experimental hall and short tunnel • 3. Beam dump • Detector design considerations: • Size comparable to COMPASS at CERN • Good momentum resolution • Good PID  RICH, TRD as well as EMCalorimetry Physics Opportunities at Future Polarized Colliders

  28. W.-D. Nowak, Int. WS on Hadron Structure, Trieste, Feb.2002 R. Kaiser & D. Ryckbosch, private comm., SPIN2002 at BNL ELFE at DESY • ELEF at DESY: • -- Inject electron beam at 30 GeV in modified HERA-e • -- Use HERA as stretcher ring  extract high duty factor • -- Measurement goal: Exclusive reactions with high precision • -- PHYSICS: Skewed parton distributions  Orbital angular momenta Physics Opportunities at Future Polarized Colliders

  29. Towards EIC at BNL…. • September 2001: EIC grew out of joining of two communities: 1) polarized eRHIC (ep and eA at RHIC) 10 GeV e X 250 GeV p or 100 GeV A BNL, UCLA, YALE and people from DESY & CERN 2) Electron Poliarized Ion Collider (EPIC) 3-5 GeV e X 30-50 GeV polarized light ions Colorado, IUCF, MIT/Bates, HERMES collaborators • February 2002: White paper submitted to NSAC Long Range Planning Review  Received enthusiastic support as a next R&D project (see: DoE Webpage for Nuclear Physics Long Range Planning) • Steering Committee: 7 members, one each from BNL, IUCF, LANL, LBL, MIT, UIUC, Yale + Contact person (AD) • ~20 (~13 US + ~7 non-US) Institutes, ~100 physicists + ~40 accelerator physicists • See for more details: EIC Web-page at “http://www.bnl.gov/eic” • Annual Meetings: MIT Sep.’01, BNL Feb.’02, BNL(?) May/June’03 • Subgroups: Accelerator WG, Physics WG, Detector WG  EPIC + eRHIC = “EIC” Physics Opportunities at Future Polarized Colliders

  30. 2GeV (5GeV) e 2-10 GeV IP12 p IP10 IP2 RHIC IP8 IP4 IP6 EIC Layout (present status) • Proposed by BINP & MIT/Bates • E-ring is ¼ of RHIC ring • Collisions in ONE interaction region • Collision energies 5-10 GeV • Injection linac 2-5 GeV • Lattice based on “superbend” magnets • Self polarization using Sokolov Ternov Effect: (14-16 min pol. Time) • IP12, IP2 and IP4 are possible candidates for collision points EMPTY PHOBOS BRAHMS PP2PP CAD/RF EMPTY PHENIX OTHER :Ring with 6 IPS (Yale’00), Linac-Ring (Yale’00), Linac-Re-circulating ring (BNL’01) STAR Physics Opportunities at Future Polarized Colliders

  31. A Detector for EIC A “4p” Detector • Scattered electrons to measure kinematics of DIS • Scattered electrons at small (~zero degrees) to tag photo production • Central hadronic final state for kinematics, jet measurements, quark flavor tagging, fragmentation studies, particle ID • Central hard photon and particle/vector detection (DVCS) • ~Zero angle photon measurement to control radiative corrections and in e-A physics to tag nuclear de-excitations • Missing ET for neutrino final states (W decays) • Forward tagging for 1) nuclear fragments, 2) diffractive physics • DETECTOR DEVELOPMENT JUST BEGINNING: Invitation to Join! -- Some early effort (W. Krasny & J. Chwastowski, Yale 00 WS) -- New effort for modified EIC ring lattice to begin BNL/MIT/UIUC/+YOU! • EIC will provide: 1) Variable beam energies 2) different hadronic species, some of them polarized, 3) high luminosity Physics Opportunities at Future Polarized Colliders

  32. A time line for EIC… “Predictions are very difficult to make, especially when they are about the future” --- Albert E. • Proposal by 2004-2005 • Expected formal approval 2005-6 Long Range Review • R&D money could start for hardware 2007 • Construction of IR and Detector begin 2007-2008 • 3-5 years for staged detector and IR construction without interfering with the RHIC running • First collisions (2010-2011)??? If any one knows how to do this earlier… -- I am listening. Physics Opportunities at Future Polarized Colliders

  33. BRAHMS & PP2PP (p) PHENIX (p) STAR (p) RHIC Accelerator Complex RHIC pC Polarimeters Absolute Polarimeter (H jet) Siberian Snakes Spin Rotators 2  1011 Pol. Protons / Bunch e = 20 p mm mrad Partial Siberian Snake LINAC BOOSTER Pol. Proton Source 500 mA, 300 ms AGS AGS Internal Polarimeter 200 MeV Polarimeter Rf Dipoles RHIC accelerates heavy ions to 100 GeV/A and polarized protons to 250 GeV Physics Opportunities at Future Polarized Colliders

  34. Carbon filament target (5mg/cm2)in the RHIC beam Measure recoil carbon ions at q~90º 100 keV < Ecarbon< 1 MeV up Si #6 Arrival time (ns) Si #1 Carbon left right Si #5 Si #2 Wave-Form Digitizer +FPGA high counting rates (~0.5 MHz) scaler measurement  dA ~ 310-4 in ~1 minute. Si #3 Si #4 down ADC values Beam’s View E950 Experiment at AGS (1999)  RHIC Polarimetry Now RHIC Polarimetry BNL,Kyoto,RBRC,RIKEN,Yale Physics Opportunities at Future Polarized Colliders

  35. BNL, RBRC, RIKEN RHIC PHENIX STAR LINAC AGS Siberian Snakes Effect of depolarizing resonances averaged out by rotating spin by large angles on each turn 4 helical dipoles  S. snake 2 snakes in each ring -- axes orthogonal to each other Physics Opportunities at Future Polarized Colliders

  36. Blue Ring, Run 1 (2000-2001) Successful Operation of the Snake • Injection with Spin Flipped:Asymmetry Flipped • Adiabatically Snake on:Horizontal polarization • Accelerate equivalent to 180o rotation:180o rotated Successful Single Snake Operation ! Physics Opportunities at Future Polarized Colliders

  37. Polarization in Run 2 (January 2002) Yellow Ring Blue Ring Physics Opportunities at Future Polarized Colliders

  38. PRHIC 10% 20% 30% PAGS Why low polarization?  AGS! Source Improvement New AGS SNAKE 2004-5 Ramp up Spead Injection 1st Year AGS power generator failure ½ ramp up speed 2x resonance effect Physics Opportunities at Future Polarized Colliders

  39. Machine Performance Expectations Physics Opportunities at Future Polarized Colliders

  40. A Case for Polarized Colliders: Excellent! • The polarized EIC and HERA for e-N scattering will enable the polarized DIS studies of nucleons in a completely new x-Q2 -- A robust physics program exists with pros and cons w.r.t. high luminosity of EIC and higher CM energy of HERA • If we are lucky: HERA II finds Physics Beyond SM, polarized HERA will be imperative to understand the chiral properties of the object(!) -- Polarized THERA program will be concentrated around this… • Physics with variable Sqrt(s) at EIC will include in addition: -- inclusive physics in DIS as well as photo-production regime -- semi-inclusive physics with good particle ID -- exclusive physics leading to DVCS, DES and further to GPDs -- study of evolution of any of the pdfs when necessary • Proof of high energy polarized proton beam is at hand with RHIC Spin • Primary physics program for TESLA-N/ELFE will limit itself to already explored x-Q2 coverage, but with significantly enhance statistical accuracy with huge luminosities hence allowing detailed studies of exclusive reactions, possibly leading to angular momenta in q and g Physics Opportunities at Future Polarized Colliders

  41. Some spin & Low x/High Q2 surprises… • Elastic e-p scattering SLAC (1950s)  Q2 ~ 1 GeV2  Finite size of the proton • Inelastic e-p scattering SLAC (1960s)  Q2 > 1 GeV2  Parton structure of the proton • Inelastic m-p scattering off p/d/N at CERN (1980s) • Q2 > 1 GeV2  Unpolarized EMC effect, nuclear shadowing? • Inelastic e-p scattering at HERA/DESY (1990s)  Q2 > 1 GeV2 •  Unexpected rise of F2 at low x •  Diffraction in e-p •  Saturation(??) • Stern & Gehrlach (1921) Space quantization associated with direction • Goudschmidt & Ulhenbeck (1926): Atomic fine structure & electron spin magnetic moment • Stern (1933) Proton anomalous magnetic moment 2.79 mN • Kusch(1947) Electron anomalous magnetic moment 1.00119m0 • Prescott & Yale-SLAC Collaboration (1978) EW interference in polarized e-d DIS, parity non-conservation • European Muon Collaboration (1989) Spin Crisis/Puzzle • E704, AGS pp scattering, HERMES (1990s) Transverse spin asymmetries (??) • RHIC Spin (2001) Transverse spin asymmetries (??) Physics Opportunities at Future Polarized Colliders

  42. Thanks….. • Many people were listed along with their work for various polarized HERA and Electron Ion Collider Workshops…. -- Many more participated but can not be mentioned…. • TESLA-N, ELFE : W.D.Nowak, R. Kaiser, D. Ryckbosch • EIC Accelerator Issues: V. Ptytsin and the EIC Accelerator group (BNL/MIT-Bates) • Initial versions of some transparencies shown in this talk were prepared with A. De Roeck(CERN) for previous workshops and presentations for polarized HERA and making the case for EIC Physics Opportunities at Future Polarized Colliders

More Related