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Overview ofeRHIC detector design studies

Overview ofeRHIC detector design studies. Outline. Kinematics reconstruction. Structure Function Measurement. eRHIC - Detector requirements. QCD basics. eRHIC - Detector design aspects. DIS - Kinematics and Structure Functions. Concluding remarks. eA eRHIC meeting BNL, October 20, 2006.

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Overview ofeRHIC detector design studies

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  1. Overview ofeRHIC detector design studies

  2. Outline • Kinematics reconstruction • Structure Function Measurement • eRHIC - Detector requirements • QCD basics • eRHIC - Detector design aspects • DIS - Kinematics and Structure Functions • Concluding remarks eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  3. Measure of momentum fraction of struck quark Measure of resolution power Measure of inelasticity DIS - Kinematics and Structure Functions • Quantitative description of electron-proton scattering eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  4. DIS - Kinematics and Structure Functions • Rutherford cross-section eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  5. Scattering of electron (Spin 1/2) on point-charge charge (Spin 0): Mott cross-section • Take into account finite charge distribution: Form factor Homogeneous sphere with edge oscillating Exponential-like constant dipole 12C Point-like constant Hofstadter, 1953 DIS - Kinematics and Structure Functions • Quantify the nucleus structure: Form factors (Elastic scattering) eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  6. Scattering of electron (Spin 1/2) on proton (Spin 1/2) Nobel Prize 1961 Electron scattering on hydrogen target: 188MeV Rosenbluth separation method: Point-charge, point-moment dσ/dΩ [cm2/sr] Mott Experiment Dirac Hofstadter θ DIS - Kinematics and Structure Functions • Quantify the nucleon structure: Form factors (Elastic scattering) eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  7. Scattering on point-like objects: Quarks! Nobel Prize 1990 Here: Deep-inelastic scattering (DIS) Friedman, Kendall and Taylor DIS - Kinematics and Structure Functions • Quantify proton structure: Structure functions (Inelastic case) • Scattering of electron (Spin 1/2) on proton (Spin 1/2) eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  8. DIS - Kinematics and Structure Functions • Structure function measurement: Formalism • In terms of laboratory variables: • Formulate this now in relativistic invariant quantities: • Instead of W1 and W2, use: F1 and F2: Longitudinal structure function: FL eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  9. Asymptotic freedom: • αs → 0 at short distances: • ⇒ perturbative QCD • αs large at long distances: • ⇒ non-perturbative QCD • Factorization: hard scale Q2 non-perturbative part QCD basics • Fundamental QCD ingredients • Evolution: • Beyond Quark-Parton model, Parton densities become functions of Q2 • Predict Q2 dependence of parton distribution functions (evolution equations) eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  10. Discovery of asymptotic freedom in the theory of strong interaction (Quantum Chromo Dynamics): Nobel prize in physics 2004 Leading-log approximation: QCD basics • Asymptotic freedom eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  11. Unpolarized proton structure: f1 f2 long-range short-range long-range QCD basics • Factorization • Three steps: • Partons (quarks/gluons) in initial state: Long distance (non-perturbative QCD domain) • ⇒Parton (quarks/gluons) distribution functions • Hard interaction: Small distances (high energies) (perturbative QCD domain) • ⇒Cross-section prediction • Quarks in final state: Long distance (non-perturbative QCD domain): • ⇒ Quarks fragment into observable hadrons described by fragmentation functions eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  12. QCD basics • Evolution (1) • The presence of QCD related diagrams leads to a modification of F2 Logarithmic violation of scaling Parton model Gluon radiation Splitting function Quark densities depend on x and Q2: eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  13. QCD basics • Evolution (2) • Consider the change of the quark density Δq(x,Q2) over an interval of ΔlogQ2 • General including other types of splitting functions: Singlet distribution Probability of finding a parton of type i with momentum fraction x which originated from parton j having momentum fraction y! Gluon distribution DGLAP evolution equations: G. Altarelli and G. Parisi, Nucl. Phys. B 126 (1977) 298; V. Gribov and L.N. Lipatov, Soc. J. Nucl. Phys. 15 (1972) 438; L.N. Lipatov, Soc. J. Nucl. Phys. 20 (1975) 96; Y.L. Dokshitzer, Soc. Phys. JETP 46 (1977) 641. eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  14. 2. Determination of cross-section and extraction of F2: bin in x and Q2 1. Determination of kinematics (e.g. electron method): Background Number of selected events Luminosity Efficiency Structure Function Measurement • Structure function measurement: Kinematic coverage and measurement eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  15. Three valence quarks and sea quarks + gluons Proton = valence quarks + QCD sea Valence quarks and QCD sea x: Momentum fraction of struck quark F2 F2 F2 Three bound valence quarks Three valence quarks QCD Structure Function Measurement • Structure function measurement: Picture of the Proton eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  16. Low Q (large wavelength λ) Medium Q (medium λ) Large Q(short λ) Structure Function Measurement • Evolution At higher and higher resolutions, the quarks emit gluons, which also emit gluons, which emit quarks, which…! eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  17. Strong violation of scaling at low x and high Q2 In contrast to: Low Q2 high x! scaling Violation of scaling: QCD prediction Structure Function Measurement • Structure function measurement: Q2 and x dependence eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  18. Structure Function Measurement • Extracting parton distribution functions • Determine F2QCD in terms of parton distribution functions • Evolve F2QCD through parton distribution functions based on evolution equations • Minimize χ2 in terms of F2QCD and F2data by adjusting parameters in xfi(x,Q2) • Net result: QCD prediction for xfi(x,Q2) and therefore F2(x,Q2) • Various global pdf analyses: • GRV • CTEQ • MRST • ZEUS/H1 i: valence (u,d), sea (s) and gluon (g) Low x: λi High x: ηi eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  19. Structure Function Measurement • Extrapolation of ZEUS NLO DGLAP fit towards low Q2 FL negative at low Q2 and low x! eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  20. Structure Function Measurement • Reconstruction of F2 eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  21. Structure Function Measurement • Reconstruction of F2 Requires unfolding! Correct for FL to get F2! eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  22. Kinematics reconstruction • Reconstruction of event kinematics • Electron method: scattered electron • Jacquet-Blondel method: hadronic final state eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  23. Kinematics reconstruction • Event kinematics (10GeV electron on 250GeV proton) Lines of constant electron angle (ϑ’e) Lines of constant electron energy (E’e) Lines of constant hadron angle (γ) Lines of constant hadron energy (F) eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  24. Low-x-low Q2: Electron and current jet (low energy) predominantly in rear direction • High-x-low Q2: • Electron in rear and current jet (High energy) in forward direction barrel • High-x-high Q2: • Electron predominantly in barrel/forward direction (High energy) and current jet in forward direction (High energy) forward rear Kinematics reconstruction • Event topology (10GeV electron on 250GeV proton) eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  25. Kinematics reconstruction • Event kinematics (5GeV electron on 50GeV proton) Lines of constant electron energy (E’e) Lines of constant electron angle (ϑ’e) Lines of constant hadron energy (F) Lines of constant hadron angle (γ) eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  26. barrel forward rear Kinematics reconstruction • Event topology (5GeV electron on 50GeV proton) • High-x-high Q2: • Electron predominantly in barrel/forward direction (High energy) and current jet in forward direction (High energy) • Low-x-low Q2: Electron and current jet (low energy) predominantly in rear direction • High-x-low Q2: • Electron in rear and current jet (High energy) in forward direction eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  27. Kinematics reconstruction • Resolution of event kinematics • Electron method: scattered electron • Jacquet-Blondel method: hadronic final state eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  28. Jet production and small-angle e tagger In addition: p tagging in forward direction Hermetic detector configuration / e- and e+ Missing energy measurement K/π separation - particle ID - Heavy flavor - Secondary vertex reconstruction and J/Psi (Forward muons) Forward acceptance: Tracking and calorimetry Inclusive measurement - electron (Low x) and hadronic final state (High x) over wide acceptance range eRHIC - Detector requirements • Polarized ep physics • Precision measurement of gp1 over wide range in Q2 • Extraction of gluon polarization through DGLAP NLO analysis • Extraction of strong coupling constant • Precision measurement of gn1 (neutron) (Polarized 3He) • Photoproduction measurements • Electroweak structure function g5 measurements • Flavor separation through semi-inclusive DIS • Target and current fragmentation studies • Transversity measurements eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  29. Inclusive measurement involving electron (Low x) - Variable √s Inclusive measurement (hadronic final state in forward direction): Good forward acceptance Similar to ep case at low x - High x: Forward acceptance - careful study necessary! Forward p tagging system - photon/electron discrimination Variable √s and positrons Forward p tagging system Inclusive measurement involving electron at small polar angles (≈10mrad) eRHIC - Detector requirements • Unpolarized ep/eA physics • Precision measurement of F2at low x: Transition from hadronic to partonic behavior • Precision measurement of the longitudinal structure function FL • Precision measurement of F2 at high x • Measurement of diffractive and exclusive reactions • DVCS • Precision measurement of eA scattering eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  30. eRHIC - Detector requirements • Detector specifications (1) • Tracking over wide acceptance range operating in high-rate environment - Contribute to reconstruction of event kinematics besides calorimetry in particular at very small energies • Calorimetry over wide acceptance range (e/h separation critical): Transverse and longitudinal segmentation (Track-calorimeter cluster matching essential) • Specialized detector systems • Zero-degree photon detector (Control radiative corrections and luminosity measurement) • Tagging of forward particles (Diffraction and nuclear fragments) such as…: • Proton remnant tagger • Zer0-degree neutron detector • Particle ID systems (K/π separation), secondary vertex reconstruction and muon system (J/Psi) eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  31. eRHIC - Detector requirements • Detector specifications (2) • High-rate rate requirement • Background rejection: Timing requirements e.g. calorimetry timing essential to reject beam related background • Trigger: Multi-level trigger system involving calorimetry and fast tracking information to enhance data sample for rare processes over inclusive ep/eA and photoproduction ATLAS eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  32. eRHIC - Detector design aspects • General considerations: Detector aspects • Measure precisely scattered electron over large polar angle region (Kinematics of DIS reaction) • Tag electrons under small angles (Study of transition region: DIS and photoproduction) • Measure hadronic final state (Kinematics, jet studies, flavor tagging, fragmentation studies, particle ID) • Missing ET for events with neutrinos in the final state (W decays) (Hermetic detector) • Zero-degree photon detector: Control radiative corrections and luminosity measurement (ep/eA Bremsstrahlung) • Tagging of forward particles (Diffraction and nuclear fragments) such as…: • Proton remnant tagger • Zero degree neutron detector • Challenge to incorporate above in one detector: Focus on two specific detector concepts for now! Constrain on machine layout! eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  33. e A eRHIC - Detector design aspects • General considerations • Design 1: Forward physics (unpolarized eA MPI Munich group): • Specialized detector system to enhance forward acceptance of scattered electrons and hadronic final state • Main concept: Long inner dipole field (7m) • Required machine element-free region: approx. ±5m • Design 2: General purpose (unpolarized/polarized ELECTRon-A): • Compact central detector (Solenoidal magnetic field) with specialized forward/rear tagging detectors/spectrometers to extend central detector acceptance • Required machine element-free region: approx. ±3m • Detector sub-systems in both design concepts: • Zero-degree photon detector (Control radiative corrections and luminosity measurement) • Tagging of forward particles (Diffraction and nuclear fragments) such as…: • Proton remnant tagger / proton spectrometer • Zer0-degree neutron detector A e eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  34. eRHIC - Detector design aspects • Design 1: Forward physics (unpolarized eA MPI-Munich group) (1) • Detector concept • Compact detector with tracking and central EM calorimetry inside a magnetic dipole field and calorimetric end-walls outside: • Bend forward charged particles into detector volume • Extend rapidity compared to existing detectors • Tracking focuses on forward and backward tracks • No tracking in central region I. Abt, A. Caldwell, X. Liu, J. Sutiak, MPP-2004-90, hep-ex 0407053 eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  35. eRHIC - Detector design aspects • Design 1: Forward physics (unpolarized eA MPI-Munich group) (2) I. Abt, A. Caldwell, X. Liu, J. Sutiak, MPP-2004-90, hep-ex 0407053 • Tracking system: • High-precision tracking with ΔpT/pT ~ 2% • Angular coverage down to η≈ 6 over the full energy range • Concept: 14 Si-strip tracking stations (40 X 40 cm) • Assumed hit resolution: 20μm • Momentum resolution from simulations: Few percent! eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  36. eRHIC - Detector design aspects • Design 1: Forward physics (unpolarized eA MPI-Munich group) (3) I. Abt, A. Caldwell, X. Liu, J. Sutiak, MPP-2004-90, hep-ex 0407053 • Calorimeter system: • Compact EM calorimeter systems: Si-Tungsten • Forward hadron calorimeter: Design follows existing ZEUS calorimeter eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  37. eRHIC - Detector design aspects • Design 1: Forward physics (unpolarized eA MPI-Munich group) (4) • Acceptance: • Full tracking acceptance for |η| > 0.75 - No acceptance in central region |η| < 0.5 • Q2 acceptance down to 0.05GeV2 (Full W range) - Full acceptance down Q2=0GeV2 for W>80GeV • High x: Electron (Q2) and Jet (x) to determine event kinematics I. Abt, A. Caldwell, X. Liu, J. Sutiak, MPP-2004-90, hep-ex 0407053 • Track efficiency: • Full efficiency below 6GeV for η > -8 • For larger energies, full efficiency for η > -5 eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  38. e A eRHIC - Detector design aspects J. Pasukonis, B.S. • Design 2: General purpose (unpolarized/polarized ELECTRon-A) (1) • Detector concept: • Hermetic detector system inside ±3m machine element free region • Starting point: • Barrel and rear EM system: e.g. Si-Tungsten (Similar to Design 1) • Forward EM/hadron calorimeter: e.g. Pb-scintillator • Tracking system and barrel EM inside solenoidal magnetic field • Tracking system based on high-precision Si (inner) and micro-pattern technology (Triple-GEM) (outer) eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  39. eRHIC - Detector design aspects J. Pasukonis, B.S. • Design 2: General purpose (unpolarized/polarized ELECTRon-A) (2) • ELECTRA detector simulation and reconstruction framework: • GEANT simulation of the central detector part (tracking/calorimetry) available: Starting point • Calorimeter cluster and track reconstruction implemented • Code available through CVS repository: • http://starmac.lns.mit.edu/~erhic/electra/ • To-do-list: • Evaluate and optimize detector configuration - In particular: Type of magnetic field configuration • Design of forward tagging system and particle ID systems • Rear detection systems • For eA events: Optimize forward detector system for high-multiplicity environment eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  40. eRHIC - Detector design aspects J. Pasukonis, B.S. • Design 2: General purpose (unpolarized/polarized ELECTRon-A) (3) • Simulated ep DIS event (LEPTO) Lower Q2 acceptance ≈ 0.1GeV2 Side view • DIS generators • used so far: • LEPTO • DJANGO eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  41. eRHIC - Detector design aspects E. Kistenev eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  42. eRHIC - Detector design aspects • IR region • Design concept: Forward physics (unpolarized eA MPI-Munich group) • Machine element free-region: approx. ±5m • Physics program could be accomplished at lower luminosity • Design concept: General purpose (unpolarized/polarized ELECTRon-A) • Machine element free-region: approx. ±3m • Physics program requires high luminosity operation • Synchrotron radiation background • Optimize beam pipe shape • Accommodate synchrotron radiation fan generated by e-beam as a result of beam separation • Maximize detector acceptance • Design of absorber and masking system • Beam-gas background • Bremsstrahlung of electrons with residual gas and proton-beam gas background • Shielding and collimation • Minimize dead-material close to the beam • Good vacuum conditions crucial eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  43. Concluding remarks • Preparation of eA case: • eA MC generators: • VNI (Not tested - requires comparison to LEPTO) • Can we get VENUS? • Incorporate saturation effects in existing MC generators? • ELECTRA: Detector simulation and reconstruction framework available • Kinematic reconstruction: • Low x : Electron • High x: Use hadronic final state. How well does this work for eA? • Multiplicity eA vs. ep, in particular in the forward direction? • Luminosity measurement? • Simulation of F2A? Which range in A? • Beyond F2A: FL and VM production • Global analysis of gluon distribution function eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  44. Concluding remarks • Critical eRHIC R&D issues • Calorimetry: Compact, high resolution, e/h separation • Tracking: High-rate, low dead material, high occupancy (Forward direction) • Forward/Rear instrumentation: Compact, high radiation environment • Magnetic field configuration: Combination of solenoid and dipole-type configuration • DAQ/Trigger system: Multi-level trigger system • Background: Synchrotron radiation absorber and shielding eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  45. Calorimetry Magnetic field IR interface : Several participating institutes chaired by 2 conveners Tracking Particle ID MC Polarimetry (e/p) Rear tagging system Forward tagging system Trigger/DAQ Concluding remarks ep/eA (Represented by two leaders in DIS/Rel.Heavy Ion) eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  46. Hadronic Calorimetry • ZEUS UCAL Module design • Depleted Uranium-Scintillator Calorimeter • 3.3 mm DU plates clad in stainless steel • 2.6 mm scintillator • e/h = 1(EM response = hadronic) • Compensating (energy from neutrals) • 18 % / √E - Electromagnetic resolution • 35% / √E - Hadronic resolution • Timing resolution: 1.5ns / √E • Modules 20cm wide • Various heights: 220 - 460cm • Coverage and depth: • Forward (FCAL): (7λ): 2.2° - 39.9° • Barrel (BCAL): 36.7° - 129.1° • Rear (RCAL): (4λ): 128.1° - 176.5° eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  47. Hadronic Calorimetry • Details on ZEUS UCAL dismantling and handling • Formal agreement between DESY and DOE that UCAL has to be shipped back to the US (DOE owns U material) • Shipping costs will be covered by DESY and DOE • Current plan in case of no further usage: • Shipment on container ship without further pre-caution of further re-usage (Transport several modules in one container) • Quotations are currently being discussed with several companies in Germany • Shipment will be carried out to Utah under supervision of ANL and DOE • Handling of UCAL modules in Utah will be carried out by a DOE contractor for long-term underground storage • Dismantling of the ZEUS detector will start in July 2007 • Current plan: Dismantle UCAL modules first with short-term storage in ZEUS experimental hall • Subsequent shipment of modules to US (Utah) over the course of < 1 year eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  48. Hadronic Calorimetry • Note to BNL management under preparation by MIT group • Excellent instrument which is fully functional with the best hadronic energy resolution • Idea: Re-use ZEUS UCAL for the forward hadronic calorimeter • Note: Uranium material belongs to DOE and has to be shipped back the US • Part to achieve a cost effective solution for a detector at eRHIC • Shipment has to be carried out differently than in case of no further usage: • One module per container • Special transport frames and shock absorbers • Difference in cost compared to no further usage eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

  49. Hadronic Calorimetry • Expression of interest: Transport ZEUS UCAL modules to BNL for EIC • Decide on FCAL/RCAL modules for optimal coverage • Transport frames could be assembled at MIT-Bates • Coordination: D. Hasell (MIT) • Difference in cost compared to no further usage would have to be covered by BNL (< $100k) • Agreement from DESY and ZEUS management: Local engineering help will be provided by ZEUS for storage and transport to container ship (Compensation: 1-2 technicans for period of 1-2 months) • Shipment of UCAL modules to BNL • Locate area in AGS experimental hall area for storage and test over several years • Test and evaluation of performance under leadership of MIT (Coordination: D. Hasell) • Note: Cost factor $20M (~1990) (Inflation (2005): $30M) (No labor cost included!). Including labor cost assuming a factor 2 would result in: $60M (2005): ZEUS modules will be provided at no further cost! eA eRHIC meeting BNL, October 20, 2006 Bernd Surrow

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