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Gluon Polarization Measurements with Polarized Protons at RHIC

Gluon Polarization Measurements with Polarized Protons at RHIC. John Koster University of Illinois, Urbana Champaign Preliminary Exam November 28, 2007. Physics Motivation: On the Origin of the Proton Spin Interpretation of Past Measurements Polarized Deep Inelastic Lepton Proton Scattering

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Gluon Polarization Measurements with Polarized Protons at RHIC

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  1. Gluon Polarization Measurements with Polarized Protons at RHIC John Koster University of Illinois, Urbana ChampaignPreliminary ExamNovember 28, 2007

  2. Physics Motivation:On the Origin of the Proton Spin • Interpretation of Past MeasurementsPolarized Deep Inelastic Lepton Proton Scattering • Discussion of Measurements in ProgressInclusive measurements with Polarized Protons collisions • New ProbesDi-Hadron measurements with Polarized Protons collisions • Instrumentation Necessary for Proposed MeasurementImplementation of a new forward calorimeter

  3. Physics Motivation Constituents: quarks = u, d, s and gluons 1fm Proton Spin Gluon Spin + Quark Spin + Orbital Angular Momentum

  4. Quark momentum fraction distribution spin dependent quark distributions spin dependent gluon distribution Physics Motivation

  5. Physics Motivation:On the Origin of the Proton Spin • Interpretation of Past MeasurementsPolarized Deep Inelastic Lepton Proton Scattering • Discussion of Measurements in ProgressInclusive measurements with Polarized Protons collisions • New ProbesDi-Hadron measurements with Polarized Protons collisions • Instrumentation Necessary for Proposed MeasurementImplementation of a new forward calorimeter

  6. Status of Polarized Distribution Functions • Up Quark polarized parallel to direction of proton spin • Highly polarized at mid-to high- x. • ∆u ~ 0.85 • From: AAC, Phys.Rev.D74:014015,2006.

  7. Status of Polarized Distribution Functions • Down Quark polarized anti parallel to direction of proton spin • Highly polarized at mid-to high- x. • ∆d ~ -0.35 • From: AAC, Phys.Rev.D74:014015,2006.

  8. Status of Polarized Distribution Functions • Assumption: Δu(x) = Δd(x) = Δs(x) at Q2=1GeV2 • AAC fit determines Δq(x) • Large uncertainties • Δq = -0.05 +/- 0.01Evaluated at Q2 = 1 GeV2 • From: AAC, Phys.Rev.D74:014015,2006.

  9. Status of Polarized Distribution Functions • Gluons distribution has large uncertainties • Sign of distribution unknown • ΔG = 0.31 +/- 0.32Evaluated at Q2 = 1 GeV2 • From: AAC, Phys.Rev.D74:014015,2006.

  10. Physics Motivation:On the Origin of the Proton Spin • Interpretation of Past MeasurementsPolarized Deep Inelastic Lepton Proton Scattering • Discussion of Measurements in ProgressInclusive measurements with Polarized Protons collisions • New ProbesDi-Hadron measurements with Polarized Protons collisions • Instrumentation Necessary for Proposed MeasurementImplementation of a new forward calorimeter

  11. Interpretation of ALL for inclusive p0 production at Leading Order in QCD for proton-proton collisions Example: Production of neutral pions ~ probe gluon content with with quark probes! experimental double spin asymmetry Jet,π0 gluon quark gluon quark Jet,π0 DIS ? QCD Accessing the Polarized Gluon Distribution Polarized DIS + Clean measurement of x - Extraction of gluon requires large range of log (Q2) Measurements of ΔG may be possible with a future high energy polarized electron-proton collider Polarized Protons + Gluons probed directly - Measurements not directly sensitive to x

  12. The Relativistic Heavy Ion Collider Brookhaven National Laboratory, Long Island

  13. Polarized Protons in RHIC RHIC pC Polarimeters Absolute Polarimeter (H jet) Siberian Snakes BRAHMS & PP2PP PHOBOS 110 Bunches1011 protons/bunch106 ns bunch spacing25 < Beam Momentum < 250 GeV Siberian Snakes PHENIX STAR Siberian Snake Spin Rotators Helical Partial Snake Partial Snake Polarized Source 1 mA, H- 70-80% polarization Strong Snake LINAC AGS BOOSTER 200 MeV Polarimeter Rf Dipole AGS pC Polarimeter Spin Evolution through Siberian Snake from:http://www.agsrhichome.bnl.gov/RHIC/Spin/spinfigs/qcdspin-mackay.pdf Spin Orbit through a Siberian Snake

  14. PHENIX Polarized Proton Data Samples * Projections JK Contributions to Data-Taking Effort: 4+ months as MPC on-call expert 2 months on shift as Shift Leader, DAQ Operator, Data Monitor or HV/LV Controller MPC Active. Thesis data set Source: http://www.bnl.gov/npp/docs/pac0307/phenix_bup.pdfhttp://www.bnl.gov/rhic_ags/users_meeting/Workshops/1/MBai.pdfand PHENIX internal discussions for 2007/2008 projections

  15. PHENIX Calorimeters Lead Scintillator and Lead Glass Muon Piston Calorimeter PHENIX Muon Piston Calorimeter PHENIX East Arm The PHENIX Detector Beam • Major Features: • Four Independent Spectrometer Arms • Flexibile event selection • High DAQ bandwidth (600 MB/s) to Disk • Good capabilities for particle identification • Limited Acceptance

  16. NCC NCC MPC-South MPC-North PHENIX Calorimetry EMCAL 0 f coverage 2p EMCAL -3 -2 -1 0 1 2 3 pseudo-rapidity Detector Upgrade in Progress Available 2012 MPC Timeline:Summer 2005 -- IdeaJanuary 2006 -- South MPC InstallationOctober 2006 -- North MPC InstallationOctober 2007 -- Upgraded Light Distribution System InstallationBoth detectors available for run 08 pp+dA

  17. Kinematics for Inclusive ALL p0with PHENIX CA Proton #2 Proton #1 • Inclusive p0measurements in PHENIX Central Arms • Probe a range in x1, x2 • Hadron pT cuts change subprocess: qg, gg, qq p0 Central Arm From S. Bazilevsky From W. Vogelsang Counts Log10(x)

  18. ALLπ0with the PHENIX Central Arms Calc. by W.Vogelsang and M.Stratmann Model Dependent Statement on the Gluon spin contribution is possible with ALL measurements done at RHIC. GRSV: M. Gluck, E. Reya, M. Stratmann, and W. Vogelsang One set of parameterizations for the helicity distributions based on a QCD analysis of DIS data. Std. gives the best agreement with DIS data

  19. Comparison to Other Helicity Distributions Parameterizations Gehrmann-Stirling Parametrizations Example: GS-C with node at x=0.1 has ∫0.020.3ΔG(x)≈0 but ∫01ΔG(x)=1 Similar for any parameterization which rises at sufficiently small x Possible to constructwhich is compatible with existing PHENIX data but still has a large gluon spin contribution

  20. +0.3     + ∫0.31 G(x) dx     + ∫0.00.02 G(x) dx  -0.2 ΔG= -0.4      - ∫0.31 G(x) dx     - ∫0.00.02 G(x) dx  √s=200 GeVp0 EMC √s=62 GeVp0Central Arm √s=200,500 GeVp0 MPC Observ. Evaluation of Extrapolation Uncertainties to Small and Large x ∆G=∫01∆G(x) dx =∫00.02∆G(x) dx+∫0.020.3∆G(x) dx+∫0.31∆G(x) dx How big or small can the unmeasured contributions be?Use G(x) as bound for ∆G(x) in unmeasured regions

  21. CTEQ 6M Integrations Unpolarized parton distributions, CTEQ 6M Estimates of ∆G with assumption of maximally polarized gluon (∆G(x)=G(x)) Functional form of ∆G(x) at large x is interesting, but maximum spin contribution is smallConstraints possible with mid rapidity measurementsLarge Potential Spin Contributions

  22. Physics Motivation:On the Origin of the Proton Spin • Interpretation of Past MeasurementsPolarized Deep Inelastic Lepton Proton Scattering • Discussion of Measurements in ProgressInclusive measurements with Polarized Protons collisions • New ProbesDi-Hadron measurements with Polarized Protons collisions • Instrumentation Necessary for Proposed MeasurementImplementation of a new forward calorimeter

  23. Selection of Kinematics at RHIC using DiJets/Hadrons • RHIC collides protons with √s = 200 GeV • Collisions with large transverse momentum similar to parton-parton elastic scattering • Reconstruct x1, x2 using kinematics of 2-body elastic collisions • Use of hadrons as jet proxies smears relation • Choice of hadron and rapidity affects observed distribution of probed x1,2 3 1 2 4 y1,2- rapidities of jets 1 and 2 pT - transverse momentum of jet

  24. Di-Hadron Event Simulations with Pythia • Pythia: Monte-Carlo simulation package for simulating high energy collisions • Unpolarized processes only • Results should not be blindly trusted • Highly tuneable • Gives detailed event information • Detector Response Not IncludedUseful for feasibility studies 101 001001100100111010100111010101 10100100110010011101010011101010010110 10100100110010011101010011101010010110 110110101011011 101 10101111100101011110011011101

  25. Use DiHadrons to Tag x North Nose Cone CalorimeterBroader x-range η4 Central ArmAntiSymmetric, high-x/low-x events South Nose Cone CalorimeterBroader x-range South MPCSelects symmetry, high-x events Log10(x2) 3, p0 – Trigger Particle Proton 1 Proton 2 JK Contributions:Study of accessing low-x through di-hadron channel in PHENIX presented at DNP07 4, p0

  26. For Each Set of pTCuts1) Generate x1,2spectra2) Find Average/RMS of each spectra3) (x,y,yerror bar) = (pT cut, Mean(x1,2), RMS(x1,2) x1 Low-x: x-distributions and subprocess fractions Subprocess Fraction Central Particle Required X1,2 p01pT -0.35 < p01 η< 0.35 p01pT Subprocess Fraction Forward and Central Particle Required X1,2 3.1 < p01η< 3.65-0.35 < p02η< 0.35 1 < p02 pT < 2 GeV/c p01pT p01pT quark-gluon scatteringgluon-gluon scatteringquark-quark scattering x1 x2

  27. Physics Motivation:On the Origin of the Proton Spin • Interpretation of Past MeasurementsPolarized Deep Inelastic Lepton Proton Scattering • Discussion of Measurements in ProgressInclusive measurements with Polarized Protons collisions • New ProbesDi-Hadron measurements with Polarized Protons collisions • Instrumentation Necessary for Proposed MeasurementImplementation of a new forward calorimeter

  28. Calorimeter Design/Construction JK Responsibility: Preparation of all crystals Mechanical Support Design, Construction and Fitting Gain Testing Crystals JK Responsibility: North MPC: Test all boards for front end electronics rack, driver boards, receiver boards Setup high energy cluster trigger, communication with PHENIX DAQ JK Responsibility: Design, Test and Build a new monitoring system for the North and South MPC’s JK Responsibility: NMPC: Prepare [now replaced] monitoring system Assist PHENIX technicians with installation. Verify successful installation with monitoring system. ElectronicsDesign/Production Revised Monitoring System Installation Contributions to the Realization of the MPC Calorimeter Design/Construction Built by a collaboration of 8 institutions led by UIUC. ElectronicsDesign/Production Revised Monitoring System Installation

  29. Pre-Amp and APD-Holder GluingUV Curing Crystal Cleaning and Tyvek Wrap APD and Crystal Gluing Wrapping Preparation Aluminum and Tetlar Wrapping Gain Test Stand MPC Construction at UIUC Nuclear Physics Lab MPC assembly team in Urbana Frank Ellinghaus Colorado Oleg Eyser UCR Don Isenhower ACU Andrey Kazantsev Kurchatov Nathan Means Stony Brook Ken Sedwick UCR Cole Watts ACU John Wood ACU Ryan Wright ACU ------------------------------------------------- John Blackburn UIUC John Koster UIUC David Layton UIUC Eric ThorslandUIUC Aaron Veicht UIUC

  30. Preparation of a Crystal Alcohol cleaning PbWO4 Crystals from Kurchatov Institute Tyvek wrap After a 36 hour cure the crystals are wrapped in aluminum foil and tetlar. Not so hard… Repeat 450 times! Glued to an APD

  31. Energy Calibration at Fermilab Fermilab e- Energies:4, 8, 16, 33 GeV Test module at beam test JK Contributions: Preparation of crystals, setup for beamtest, data taking shifts Meson Test Beam Facility

  32. MPC Installation PHENIX Technicians installing the SMPC Fully Prepared Modules Beampipe Installed NMPC NMPC FEM

  33. MIP Peak Calibration using Minimum Ionizing Particle Counts

  34. Calibration using p0 Invariant Mass Peak All Pairs Mixed Events Background subtracted Counts Counts • Two photon invariant mass spectrumPhoton Pair Cuts • Pair Energy > 8 GeV • Asymmetry |E1-E2|/|E1+E2| < 0.6 • Noisy Towers (up to 25% of MPC) Excluded • Width ~ 20 MeVFrom: Mickey Chiu

  35. p+p0+X at s=62.4 GeV/c2 Left Right Transverse Single Spin Asymmetry: AN at √s = 62.4 GeV First MPC Result!

  36. Summary Large gluon spin contributions are possible at low x Proposed ALL measurement will access this region Forward Calorimeter designed, built, installed and operated. Large data sets already available with even larger samples soon to come

  37. Extras

  38. High-X: x-distributions and subprocess fractions <x1,2> SubProcess Fraction Single MPC <x1,2> Di-MPC Pi0 Energy Cut [GeV] Pi0 Energy Cut [GeV] quark-gluon scatteringgluon-gluon scatteringquark-quark scattering x1 x2

  39. Simulations from Marco Stratman on di hadron production at forward and mid rapidity

  40. High-X DiMPC Projected Statistical Error Bars for Run 08Di-MPCValues for E>30 GeV not generated because insufficient Pythia Statistics

  41. Low-X: x-distributions and subprocess fractions

  42. Physics Output Contribution to Reaction Plane Measurement in AA Collisions The solid symbols are average cos values, whileThe open symbols are average sin. blue  : rxn_S - rxn_Nred   : mpc_S - mpc_Nblack : bbc_S - bbc_Npink  : rxn - mpcgreen : rxn - bbc

  43. Beam Test Details Proton beam Al target • MTBF - Secondary Beam from 120 GeV protons of Main Injector into Al target • Momentum from 3 GeV to 120 GeV possible • 4 second spills every two minutes, 4 cm spot size (momentum dependent)

  44. PbWO4 Scintillating Crystals • Dimensions: 2.2 x 2.2 x 18 cm3 • Radiation length: 0.89 cm • Moliere radius: 2.0 cm : Smallest known scintillator moliere radius • Hadronic Interaction Length: 22.4 cm • Main emission lines: λ = 420-440 nm, 500 nm. • Scintillating crystals on loan from the Kurchatov Institute, Russia. • Developed for ALICE in collaboration with the North Crystal Company in Apatity, Russia.

  45. APD + Preamp • APD/Preamp Holder • PbW04 Crystal Avalanche Photodiodes and Preamp • APD’s • Developed for the CMS experiment • Manufactured by the Hamamatsu Corporation • Peak response around main emission lines of crystal (420-440, 500 nm) • Preamps • Preamps contributed by Hiroshima University, Japan. • Developed for the ALICE and modified by Hiroshima U.

  46. Preparing the Area • Before the lid comes off the box you should have: • Alcohol to clean the crystals • Kim wipes • Q-tips • Well padded work areas – the crystals can be damaged by contact with metal or sudden impacts. UIUC used the foam from the boxes + felt + several layers of Kimwipes. • A diamond tipped scribe • Gluing stands

  47. Unpacking the Crystals: Person #1 A box with the lid off crystal • Pry off the lid. • You should find a packing list • The crystals are wrapped in cotton and paper (paper on the inside) • As you unpack the crystals cross their ID off the packing list

  48. Scribing + Rough Cleaning: Person #1 An unwrapped crystal Crystal ID would go here Arrow – done with a marker Crystal ID • Scribe the crystal ID onto the crystal. It should be put in the direction of the arrow. Be extremely careful to do this. Sometimes the arrow will point towards the sticker. • Scratch off the crystal ID. • Do a rough cleaning with an alcohol soaked Kim-wipe. Get rid of sticker residue and the arrow • Write the crystal ID on a thin strip of paper and put the crystal on top of it.

  49. Fine Cleaning + Tyvek Wrap A tyvek wrapped crystal Photo diode end tape APD end • Person #2 wears cotton gloves almost the entire time • Do a fine cleaning of the crystal. I recommend using two passes on each crystal face with a clean, alcohol-soaked kim wipe. • Wrap the crystal in the pre-cut tyvek: Take off one glove. Use it to tape the tyvek at the flap, and at the side. Your gloved hand should be holding the crystal • Warning: The crystal can and will slip out the un-taped end. Be very careful

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