Thessaloniki, June 5, 2003 It takes glue to study the “Glue” Zisis Papandreou Dept. of Physics University of Regina Zisis Papandreou Dept. of Physics University of Regina Canadians: Regina,Carleton

References Design Report Nov 2002 Sept/Oct 2000 Feb 2001 Sept 2000 JLab whitepaper Cover story article on exotics and Hall D Article on exotics and Hall D All can be downloaded from the Hall D website

Scientific Goals and Means Definitive and detailed mapping of hybrid meson spectrum Quantitative understanding of confinement mechanism in Quantum Chromodynamics (QCD). Search for smoking gun signature of exotic J PC hybrid mesons; these do not mix with qq states Tools for the GlueX Project: –Accelerator: 12 GeV electrons, 9 GeV linearly polarized photons with high flux –Detector: hermiticity, resolution, charged and neutrals, R&D –PWA Analysis: each reaction has multi-particle final states –Computing power: 1 Pb/year data collection, data grids, distributed computing, web services… -

white QCD is the theory of quarks and gluons 3 Colors 3 Anti-colors 8 Gluons, each with a color and an anti-color charge. (colorless objects) confinement

Jets at High Energy Direct evidence for gluons come from high energy jets. But this doesn’t tell us anything about the “static” properties of glue. We learn something about  s. 2-Jet 3-Jet gluon bremsstrahlung

Deep Inelastic Scattering As the nucleon is probed to smaller and smaller x, the gluons become more and more important. Much of the nucleon momentum and most of its spin is carried by gluons! Glue is important to hadronic structure. x = q 2 /2M, 0<x<1

QCD and confinement Large Distance Low Energy Small Distance High Energy Perturbative Regime Non-Perturbative Regime High Energy Scattering Gluon Jets Observed Spectroscopy Gluonic Degrees of Freedom Missing

Strong QCD: See and systems. white Nominally, glue is not needed to describe hadrons. Allowed systems:,, GlueballsHybridsMolecules Gluonic Excitations u d s c b t Six Flavors of quarks GlueX Focus: “light-quark mesons”

Flux Tubes Color Field: Gluons possess color charge: they couple to each other! DipoleFlux Tube 1 electric charge  carries no charge 3 Color charges g carry charge Notion of flux tubes comes about from model-independent general considerations: observed linear dependence of m 2 on J. Idea originated with Nambu in the ‘70s.

Lattice QCD Flux tubes realized linear potential r/fm V o ( r) [GeV] From G. Bali Lattice “measurement” of quenched static potential

“Pluck” the Flux Tube Normal meson: flux tube in ground state Hybrid meson: flux tube in excited state There are two degenerate first-excited transverse modes with J=1 – clockwise and counter-clockwise – and their linear combinations lead to J PC = 1 – + or J PC =1 + – for the excited flux-tube How do we look for gluonic degrees of freedom in spectroscopy?

Mass Difference 1 GeV/c 2 mass difference Hybrid mesons Normal mesons r - quark separation

m=0 CP=(-1) S+1 m=1 CP=(-1) S Flux-tube Model ground-state flux-tube m=0 excited flux-tube m=1 built on quark-model mesons CP={(-1) L+S }{(-1) L+1 } ={(-1) S+1 } S=0,L=0,m=1 J=1 CP=+ J PC =1 ++,1 -- non exotic S=1,L=0,m=1 J=1 CP=- J PC =0 -+, , ,2 +- exotic normal mesons Hybrid Mesons 1 -+ or 1 +- exotic  K

linear potential ground-state flux-tube m=0 excited flux-tube m=1 Gluonic Excitations provide an experimental measurement of the excited QCD potential. Observations of exotic quantum number nonets are the best experimental signal of gluonic excitations. QCD Potential

Meson Map 1 Glueballs Hybrids Mass (GeV) qq Mesons L = J PC = 1 -- J PC = 0 -+ (L = qq angular momentum) Each box corresponds to 4 nonets (2 for L=0) (2S+1) L J = 3 S 1 (2S+1) L J = 1 S 0

Mass (GeV) qq Mesons L = Each box corresponds to 4 nonets (2 for L=0) Radial excitations (L = qq angular momentum) exotic nonets 0 – – – 1 – + 1 – – 2 – – – + 2 – Glueballs Hybrids Meson Map GeV Lattice GeV

Production of Exotics A pion or kaon beam, when scattering occurs, can have its flux tube excited  or  beam Quark spins anti-aligned Much data in hand with some evidence for gluonic excitations (exotic hybrids are suppressed) q q before q q after q q q q before  beam Almost no data in hand in the mass region where we expect to find exotic hybrids when flux tube is excited Quark spins aligned _ _ _ _

Phenomenology Model predictions for regular vs exotic meson prodution with pion (S=0) and photon (S=1) probes Szczepaniak & Swat

Partial Wave Analysis (PWA) A simple example - identifying states which decay into  Decay into     implies J=L, P=(-1) L and C=(-1) L Production and decay point the way C.M.S. Line shape and phase consistent with Breit-Wigner line shape Low t production Identify the J PC of a meson Determine production amplitudes & mechanisms Include polarization of beam, target, spin and parity of resonances and daughters, relative angular momentum. f(  )= (1/k)  (C l /l)sin  l P l (cos  ) d  =  f(  )  2 d 

Decay Angular Distributions J PC =2 ++ J PC =3 -- C.M.S. J PC =1 -- Place PWA tools on firm footing, years before experiment effects of polarized and unpolarized beam detector acceptance (hermetic) Leakage of non-exotics into exotic signal GlueX uses two parallel PWA codes for cross-checking!

Finding the Exotic Wave PC The Jexotic was in the mix with other waves at the level of 2.5% The generated mass and width are compared with those from PWA fits: Mass Input: 1600 MeV Width Input: 170 MeV Output: /- 3 MeV Output: 173 +/- 11 MeV Statistics correspond to a few days of running Double-blind MC exercise  p       n J PC =1 -+  1

What is Needed for the GlueX Experiment?  PWA requires that the entire event be kinematically identified - all particles detected, measured and identified. It is also important that there be sensitivity to a wide variety of decay channels to test theoretical predictions for decay modes. The detector should be hermetic for neutral and charged particles, with excellent resolution and particle identification capability. The way to achieve this is with a solenoidal-based detector. Hermetic Detector:  Linear Polarization is required by the PWA  At least 12 GeV electrons  Small spot size and superior emittance  CW beam minimizes detector deadtime, permitting much higher rates Linearly Polarized, CW Photon Beam:

Why a 12 GeV Electron Beam? The mass reach of GlueX is up to about 2.5 GeV/c 2 so the photon energy must at least be 5.8 GeV. Energy must be higher than this so that: 1.Mesons have enough boost so decay products are detected and measured with sufficient accuracy. 2.Line shape distortion for higher mass mesons is minimized. 3.Meson and baryon resonance regions are kinematically distinguishable. 4.Linear polarization is optimal. But the photon energy should be low enough so that: 1.An all-solenoidal geometry (ideal for hermeticity) can still measure decay products with sufficient accuracy. 2.Background processes are minimized. 9 GeV photons ideal

flux photon energy (GeV) 12 GeV electrons Coherent Bremsstrahlung This technique provides requisite energy, flux and polarization collimated Incoherent & coherent spectrum tagged with 0.1% resolution 40% polarization in peak electrons in photons out spectrometer diamond crystal

Linear Polarization Linear polarization is: Essential to isolate the production mechanism (M) if X is known A J PC filter if M is known (via a kinematic cut) Degree of polarization is directly related to required statistics Linear polarization separates natural and unnatural parity States of linear polarization are eigenstates of parity. States of circular polarization are not. M

Experimenta 2 yieldExotic Yield SLAC BNL (published) BNL (in hand - to be analyzed) GlueX10 7 5x 10 6 More than 10 4 increase GlueX estimates are based on 1 year of low intensity running (10 7 photons/sec) Even if the exotics were produced at the suppressed rates measured in  -production, we would have 250,000 exotic mesons in 1 year, and be able to carry out a full program of hybrid meson spectroscopy How GlueX Compares to Existing Data

Computational Challenge GlueX will collect data at 100 MB/sec or 1 Petabyte/year - comparable to LHC-type experiments. GlueX will be able to make use of much of the infrastructure developed for the LHC including the multi-tier computer architecture and the seamless virtual data architecture of the Grid. To get the physics out of the data, GlueX relies entirely on an amplitude-based analysis - PWA – a challenge at the level necessary for GlueX. For example, visualization tools need to be designed and developed. Methods for fitting large data sets in parallel on processor farms need to be developed. Close collaboration with computer scientists has started and the collaboration is gaining experience with processor farms.

LRP NSAC Long Range Plan

Jefferson Lab Facility Newport News, Virginia ABC Hall D will be located here D

6 GeV CEBAF 11CHL-2 12 Upgrade magnets and power supplies Two 0.6 GV linacs 1.1 Beam Power: 1MW Beam Current 5 µA Emittance: 10 nm-rad Energy Spread: 0.02%

GlueX Collaboration US Experimental Groups A. Dzierba (Spokesperson) - IU C. Meyer (Deputy Spokesperson) - CMU E. Smith (JLab Hall D Group Leader) L. Dennis (FSU)R. Jones (U Conn) J. Kellie (Glasgow)A. Klein (ODU) G. Lolos (Regina) (chair)A. Szczepaniak (IU) Collaboration Board Carnegie Mellon University Catholic University of America Christopher Newport University University of Connecticut Florida International University Florida State University Indiana University Jefferson Lab Los Alamos National Lab Norfolk State University Old Dominion University Ohio University University of Pittsburgh Renssalaer Polytechnic Institute University of Glasgow Institute for HEP - Protvino Moscow State University Budker Institute - Novosibirsk University of Regina CSSM & University of Adelaide Carleton University Carnegie Mellon University Insitute of Nuclear Physics - Cracow Hampton University Indiana University Los Alamos North Carolina Central University University of Pittsburgh University of Tennessee/Oak Ridge Other Experimental Groups Theory Group 100 collaborators 25 institutions

The impact of Chair of Collaboration board: George Lolos Hardware working group co-leader: Zisis Papandreou Software working group co-leader : Ed Brash Most recent Hall D Collaboration meeting was held at UofR. SPARRO has been tasked with the design and construction of the full barrel calorimeter: weight of 30 tons, 5,000 km of fibers, and a price tag of US$4,000,000. Initial R&D is ongoing at Regina; JLab discretionary funds Assembly and machining of full modules in Edmonton. S ubatomic P hysics A t R egina with R esearch Offshore

GlueX Detector Lead Glass Detector Superconducting Solenoid Electron Beam from CEBAF Coherent Bremsstrahlung Photon Beam Tracking Target Cerenkov Counter Time of Flight Barrel Calorimeter Note that tagger is 80 m upstream of detector

Barrel Calorimeter Tracking Package Rail System Lead/scintillating fiber sandwich; 1-mm diameter fibers; 0.5mm sheets PMT Readout Scintillating fiber

Barrel Calorimeter Design Issues Length of device (> 4 m) Shower containment/radiation lengths: ~16Xo Azimuthal granularity vs. PMT geometry & light collection Minimum energy deposition threshold: 20 MeV Neutral energy resolution balance (vs. FCAL) –Fiber diameter & Pb thickness: uniform throughout? Charged vs. Neutral energy resolution balance Timing resolution vs. other subsystems Mechanical issues: manufacturing, inner detector mounting R&D at Regina: Monte Carlo Hardware: Readout, fibers, Pb/SciFi Matrix

What’s a Hybrid? Proximity-focused vacuum tube Fast rise- and fall-time (2, 12 ns) High QE for UV, Gain is 10 5 Insensitive to high magnetic fields Fused silica window HV: -8kV Bias: -80V Pre-amp Shaper 2 Tesla Central Field means HPMTs or 20m fiber light guides

Hybrid PMT DEP PP0350G DEP PP0100Z UofR HV regulator R&D: –NaI detector –Scintillator Parameters measured CREMAT CR-101D System works: –Pre-amp –R&D on circuit –Price issue

Optical Fiber Tests with 100MeV pions Properties: –Light collection efficiency (cladding) –Scintillation light production (doping) –Light attenuation coefficient –Timing resolution Fibers Types (single-, double-clad) –Kuraray SCSF-81 –Pol.Hi.Tech –Bicron (too expensive) M11 Experimental Area at TRIUMF August 2001 Attenuation: ~3m (Kuraray) Performance/Price: (Pol.Hi.Tech.)

Fiber Optical Properties Quality Control of Fibers –Quick, reliable, reproducible Commercial system was used Components: SD2000 spectrometer, ADC1000USB, laptop, fibers, neutral density filters, connectors, lenses, optical grease, light source. Kuraray, PHT fibers have been tested for transmission and attenuation. Master Branch (Gold fibers) Slave Branch (Test fibers)

Prototype Pb/SciFi Modules Build in May 2002 with help from KLOE Folks P. Campana F. Cervelli e Technici

Prototype Module Construction 96 x 13 x 10 cm 3 70 kg B. Klein, J. Kushniryk, T.Summers, G. Williams Lead Sheet Swaging Matrix gluing & pressing Inspection and cleaning

1-m “Baby” Module

Finished Prototype

But… Next: 2-m module just completed

Conclusions An outstanding and fundamental question is the nature of confinement of quarks and gluons in QCD. Lattice QCD and phenomenology strongly indicate that the gluonic field between quarks forms flux-tubes and that these are responsible for confinement. The excitation of the gluonic field leads to an entirely new spectrum of mesons and their properties are predicted by lattice QCD. But data are needed to validate these predictions. Only now are the tools in place to carry out the definitive experiment and JLab – with the energy upgrade – is unique for this search. If exotic hybrids are there, we will find them! In Regina, we will continue the R&D on MC, HPMTs and Pb/SciFi We are eagerly awaiting CD-0 from the DOE. The right people are in place - ready to make this happen

Backup Slides beyond this point

Flux Tubes and Confinement Color Field: Because of self interaction, confining flux tubes form between static color charges mesons Linear potential: infinite energy required to separate qq. - Confinement arises from flux tubes !

Normal Mesons Spin/angular momentum configurations & radial excitations generate our known spectrum of light quark mesons Nonets characterized by given J PC L=0, S=0: O -+ pseudoscalar mesons L=0, S=1: 1 -- vector mesons L=1, S=1: O ++ scalar, 1 ++ axial vector, 2 ++ tensor nonets

Hybrid Predictions Lattice calculations nonet is the lightest UKQCD (97) 1.87  0.20 MILC (97) 1.97  0.30 MILC (99) 2.11  0.10 Lacock(99) 1.90  0.20 Mei(02) 2.01  0.10 ~2.0 GeV/c Splitting  0.20 Flux-tube model: 8 degenerate nonets 1 ++, ,0 +-,1 -+,1 +-,2 -+,2 +- ~1.9 GeV/c 2 S=0 S=1

NN  e X  , ,   1 I G (J PC )=1 - (1 -+ )  ’ 1 I G (J PC )=0 + (1 -+ )  1 I G (J PC )=0 + (1 -+ ) K 1 I G (J PC )= ½ (1 - )  1    1   b 1,   ’ 1   Couple to V.M + e 1 -+ nonet Exotics in Photoproduction Hybrid Decays modes need to be measured

Current Evidence GlueballsHybrids Overpopulation of the scalar nonet and LGT predictions suggest that the f 0 (1500) is a glueball See results from Crystal Barrel J PC = 1 -+ states reported  1 (1400)   1 (1600)  See results from BNL E852 Complication is mixing with conventional qq states Not without controversy Have gluonic excitations already been observed ?

f 0 (1500) f 2 (1270) f 0 (980) f 2 (1565)+  700,000  0  0  0 Events Crystal Barrel Results f 0 (1500) 250,000  0 Events Discovery of the f 0 (1500) f 0 (1500)   ’, KK, 4  f 0 (1370)   Crystal Barrel Results Establishes the scalar nonet Solidified the f 0 (1370) Discovery of the a 0 (1450)

An Exotic Signal in E852 Leakage From Non-exotic Wave due to imperfectly understood acceptance Exotic Signal Correlation of Phase & Intensity 3  m=  =  ’ m=  =  1 (1600)

What Electron Beam Characteristics Are Required? Coherent bremsstrahlung will be used to produce photons with linear polarization so the electron energy must be high enough to allow for a sufficiently high degree of polarization - which drops as the energy of the photons approaches the electron energy. At least 12 GeV electrons In order to reduce incoherent bremsstrahlung background collimation will be employed using 20 µm thick diamond wafers as radiators. Small spot size and superior emittance The detector must operate with minimum dead time Duty factor approaching 1 (CW Beam)

Photon Beam Energy Figure of Merit Electron energy Photon energy Given that 9 GeV photons are ideal - 12 GeV electron energy suffices; lower than this seriously degrades polarization and tagged hadronic rate.

BNL SLAC 18 GeV/c19 GeV a2a2 a2a2 We will use for comparison – the yields for production of the well-established and understood a 2 meson Compare Pion and Photoproduction Data Rates

Photoproduction of 3π at SLAC and JLab SLAC similar cuts SLAC 19 GeV CLAS 5.7 GeV a2a2 a2a2

Lattice gauge theory invented Quenched Hybrid Spectrum Hybrid Mixing Hybrids in Full QCD Exotic candidate at BNL First data from GeV Tflop-year Lattice Meson spectrum agrees with Experiment Flux tubes between Heavy Quarks FY03 Clusters 0.5 TFlop/sec FY06 Clusters 8 Tflop/sec LQCD

LRP

The Site and Beamline Work at JLab on civil issues At Glasgow and U Connecticut, progress on diamond wafers

Particle Identification TOF tests in Russia - Serpukhov Magnetic shielding studies Cerenkov counter

Coils Iron Yokes FDC Barrel Calorimeter CDC Vertex Detector Target GlueX Detector Central Field: 2 Tesla

Detector Platform Top View of the HALL PLATFORM The Platform is 8 ft from the base Supports the extracted components Assists in assembling the parts All Dimensions in Meters

Solenoid Assembly Hall D

Solenoid & Lead Glass Array At SLAC Now at JLab MEGA magnet at LANL Lead glass array Magnet arrives in Bloomington

Tracking R&D on central tracker at Carnegie Mellon Start Counter

Computational Tools for Simulations  Energy resolution:  Driving physics processes  Detector subsystems relation  Timing resolution:  Detector subsystems relation  Longitudinal position requirement?  Detector subsystems relation HDFastGEANT Notes: use a 2 decay or fake  to look at particle distributions; use known smearing from FCAL and KLOE to do the first order resolution modeling. Is the missing mass resolution important?  Neutral and charged particle energy deposition profile  Readout granularity  Lateral energy spread  Verify back-of-the-envelope X 0  Pb/SciFi/Glue detailed modeling  Position resolution (vs. angle): pos.res./  N; shower algorithms Notes: results of simulations have to be reconciled with mechanical constraints (HPMT outer and inner diameter; area reduction factor from Winston cones). Tools are now in place at Regina

BCAL Readout Configuration Longitudinal View K. Wolbaum Even with SciFi bundling, ~540 HPMTs will be needed: No of phi segments54 Phi segment angle0.116 HPD active area5.07 cm 2 HPD total area20.3 cm 2 Calorimeter thickness20.27 cm Outer calorimeter radius89.71 cm Calorimeter length400 cm No of HPMT’s1080 oLength: 4.5 m oOuter Radius: 90 cm oThickness: cm $$ cost issue $$

Light sources: –NaI crystal and 241 Am, 137 Cs and 60 Co sources –LED (pulsed): neutral density filter, fiber lightguide Measurements: HPD PP0350G with Multi- Channel Analyzer (Tektronix 5200) and DAQ System Bottom line: system works, needs a bit more R&D HPMT Innards CREMAT CR-101D

Attenuation Length ~3m

”Cave” Optical System Setup Optical system Spectrometer ADC Laptop Master (Gold) Slave (tests) Master Branch (Gold fibers) Slave Branch (Test fibers) L. Snook

Coupling Reproducibility Kuraray Multi-Clad 2002 Batch 4000 Wavelength (nm) Intensity (from Aug. 8-12, 2002)

4000 Intensity Wavelength (nm) m (#2) 1m (#1) 2m 3m 4m 5m 10m Kuraray Multi-Clad 2002 Batch Attenuation Determination

Lead Roll