1. Elton S. Smith University of Virginia October 25, 2005 1 Overview Bremsstrahlung Tagging Spectrometer and Photon Beam Review Elton S. Smith Jefferson Lab Requirements Summary of beamline and rates Status of project

2. Elton S. Smith University of Virginia Oct 25, 2005 2 Normal mesons: glue is passive Hybrid mesons: glue is excited The physics goal of GlueX is to map the spectrum of hybrid mesons starting with those with the unique signature of exotic J PC. Identifying J PC requires an amplitude analysis which in turn requires linearly polarized photons detector with excellent acceptance and resolution sensitivity to a wide variety of decay modes which include photon and charged particles This, coupled with a hybrid mass reach up to 2.5 GeV, requires 9 GeV photons produced using coherent bremsstrahlung from 12 GeV electrons. Physics goals and key features

3. Elton S. Smith University of Virginia Oct 25, 2005 3 The GlueX Detector Design has been driven by the need to carry out Amplitude analysis.  p X  n,p Photoproduction  1 → a + 1    → (     )(   ) →         h 0 → b o 1    → (   )  →      Final state particles  ± K ±  p n K L h’ 2 → K + 1 K − →  o K + K − →  +  − K + K −  1  1  ’ 1 b 2 h 2 h’ 2 b 0 h 0 h’ 0 all charged many photons strange particles 1 −+ 2+−2+− 0+−0+− Search for QCD Exotics

4. Elton S. Smith University of Virginia Oct 25, 2005 4 Mass Predictions Lowest mass expected to be  1 (1 −+ ) at 1.9±0.2 GeV Lattice 1 -+ 1.9 GeV 2 +- 2.1 GeV 0 +- 2.3 GeV

5. Elton S. Smith University of Virginia Oct 25, 2005 5 Line shape distortion M=2.5 GeV M=2.8 GeV M X (GeV)

6. Elton S. Smith University of Virginia Oct 25, 2005 6 J=0 – or 0 + V X Parity conservation implies:  are sensitive to production mechanism

7. Elton S. Smith University of Virginia Oct 25, 2005 7 Strategy for Exotic Meson Discovery  Use 8 – 9 GeV polarized photons (12 GeV electron beam) ─ Sensitivity to mesons masses up to 2.5 GeV ─ Expect production of hybrids to be comparable to normal mesons ─ Dearth of experimental data  Use hermetic detector with large acceptance ─ Decay modes expected to have multiple particles ─ hermetic coverage for charged and neutral particles ─ high data acquisition rate to enable amplitude analysis  Perform partial-wave analysis ─ identify quantum numbers as a function of mass ─ check consistency of results in different decay modes

8. Elton S. Smith University of Virginia Oct 25, 2005 8 Requirements for photon beam  Coherent peak ~ 8.4 ─ 9 GeV  Linear polarization  High rates ─ Initial running at 10 7  /s in the coherent peak ─ Design system with a clear path to 10 8  /s

9. Elton S. Smith University of Virginia Oct 25, 2005 9 6 GeV CEBAFCHL-2 Upgrade magnets and power supplies 12 Enhance equipment in existing halls add Hall D (and beam line)

10. Elton S. Smith University of Virginia Oct 25, 2005 10 Hall D Complex Accelerator East Arc

11. Elton S. Smith University of Virginia Oct 25, 2005 11 Top View 75 m Tagger Area Experimental Hall D Electron beam Coherent Bremsstrahlung photon beam Solenoid- Based detector Collimator Photon Beam dump East arc North linac Tagger area Hall D Electron Beam dump Photon beam and experimental area

12. Elton S. Smith University of Virginia Oct 25, 2005 12 GlueX / Hall D Detector Electron Beam from CEBAF Lead Glass Detector Solenoid Coherent Bremsstrahlung Photon Beam Tracking Target Cerenkov Counter Time of Flight Barrel Calorimeter Note that tagger is 80 m upstream of detector Detector Review Oct 20-22, 2004

13. Elton S. Smith University of Virginia Oct 25, 2005 13 GlueX detector CapabilityQuantityRange Charged particlesCoverage 1 o <  < 170 o Momentum Resolution (5 o -140 o )  p /p = 1 − 2% Position resolution  = 150-200  m dE/dx measurements 20 <  < 140 o Time-of-flight measurements  t = 60 ps Cerenkov and  /K separation  < 14 o Barrel time resolution  t < (150 + 50 /√E) ps Photon detectionEnergy measurements 2 <  < 120 o Veto capability  > 120 o Barrel energy resolution (E > 20 MeV)  E /E = (2 + 5/√E)% Lead glass energy resolution (E > 100 MeV)  E /E = (3.6 + 7.3/√E)% Barrel position resolution  z ~ 4 cm Lead glass position resolution  x,y = 0.7 cm DAQ/triggerLevel 1 200 kHz at 10 8  /s Level 3 event rate to tape15 kHz Data rate100 MB/s ElectronicsFully pipelineFlash ADCs, multi-hit TDCs Photon FluxTagged rate Initially: 10 7  /s, Final: up to 10 8  /s

14. Elton S. Smith University of Virginia Oct 25, 2005 14 The GlueX collaboration has designed and optimized the detector to study gluonic excitations. Many university groups have contributed to the R&D and development of major subsystems. SolenoidJLab Detectors Tracking Carnegie Mellon, Ohio U, Florida International U Calorimetry U of Regina, Florida State, Indiana U, Inst for High Energy Physics (Protvino), U of Athens PID Indiana U, Inst for High Energy Physics, U of Tenn, ORNL Computing JLab, U of Regina, Indiana U, Carnegie Mellon, U Connecticut, Christopher Newport U Electronics Indiana U, JLab, U of Alberta, Indiana U Cyclotron Beamline Catholic U of America, Glasgow U, U of Connecticut Infrastructure JLab Institutional Responsibilities

15. Elton S. Smith University of Virginia Oct 25, 2005 15 Interface between accelerator and Hall D  The accelerator will be responsible for the electron beamline, and Hall D will be responsible for the photon beam. This is the nominal breakdown of responsibilities, with additional clarification in the next two paragraphs.  The accelerator will deliver and monitor the 12 GeV electron beam to the radiator immediately upstream of the tagger magnet. The accelerator will also be responsible for steering the beam to the electron beam dump. Some monitoring of the electron beam at the dump may be required to insure accurate delivery.  Hall D will be responsible for purchasing and qualifying the crystal radiators, all aspects of the tagger magnet and hodoscope systems, collimation of the photon beam immediately upstream of the photon hall, and monitoring of the photon beam from the radiator to the photon beam dump behind the GlueX detector.

16. Elton S. Smith University of Virginia Oct 25, 2005 16 flux photon energy (GeV) 12 GeV electrons This technique provides requisite energy, flux and polarization collimated Incoherent & coherent spectrum tagged 0.1% resolution 40% polarization in peak electrons in photons out spectrometer diamond crystal Coherent Bremsstrahlung Hadronic Backgrounds

17. Elton S. Smith University of Virginia Oct 25, 2005 17 High sensitivity → high rates Start with 8.4 - 9.0 GeV Tagged 30 cm target cross section = 120 µb low-rate high-rates: multiply by factor of 10

18. Elton S. Smith University of Virginia Oct 25, 2005 18 peak energy 8 GeV 9 GeV 10 GeV 11 GeV N  in peak 185 M/s 100 M/s 45 M/s 15 M/s peak polarization 0.54 0.41 0.27 0.11 (f.w.h.m.) (1140 MeV)(900 MeV)(600 MeV)(240 MeV) peak tagging eff. 0.55 0.50 0.45 0.29 (f.w.h.m.) (720 MeV)(600 MeV)(420 MeV)(300 MeV) total hadronic rate 385 K/s 365 K/s 350 K/s 345 K/s (in tagged peak) ( 26 K/s) (14 K/s) (6.3 K/s) (2.1 K/s) 1.Total hadronic rate is dominated by the resonance region 2.For a given electron beam and collimator, background is almost independent of coherent peak energy, comes mostly from incoherent part. 3. The following assumes a 12GeV electron beam energy. Photon Beam Rates and Backgrounds

19. Elton S. Smith University of Virginia Oct 25, 2005 19 Today’s presentations Photon beam Electron beam 4. Tagger magnet design 5. Spectrometer optics Vacuum chamber 75 m Electron beam Detector Collimator Photon Beam dump Hodoscope: 6. Fixed array and beam monitoring 7. Tagger Microscope 1. Overview 2. Photon beam 3. Simulation and backgrounds

20. Elton S. Smith University of Virginia Oct 25, 2005 20 Architect’s rendering of Hall D complex Service Buildings Hall D Cryo Plant Counting House

21. Elton S. Smith University of Virginia Oct 25, 2005 21 Interface between civil construction and Hall D  The schematic drawings of the Hall D complex are the basis for estimating the shielding required for the experiment. The cost in the civil construction will include all overburden as well as steel identified in the drawing, including ─ steel for electron beam dump ─ steel for photon beam dump ─ steel covering the collimator enclosure. ─ steel wall in the accelerator tunnel upstream of the tagger building.  The Hall D budget will include all steel which is contained inside the collimator enclosure. The reason for this is that the steel will be added after the civil construction is complete and the amount and shape of the steel will be refined by optimizing the photon collimation system.

22. Elton S. Smith University of Virginia Oct 25, 2005 22 JLab 12 GeV Upgrade Project Status Successful Project Review (Jul 2005), CD-1 expected soon Four-year construction project planned to start in FY08 Review of Science program for the 12-GeV Upgrade (Apr 2005) From the Executive Summary: “After a decade of research, we should know whether the formation of flux tubes by the gluon fields is the mechanism of confinement…” Highlight in the 20-year plan of the Office of Science (2003) What’s New: “New supercomputing studies indicate that force fields called “flux-tubes” may be responsible [for the mechanism that confines quarks], and that exciting these should lead to the creation of never-before-seen particles.” Determination of “Mission Need” CD-0 (Apr 2004)

23. Elton S. Smith University of Virginia Oct 25, 2005 23 GlueX Reviews December 1999: PAC Requested Review of the GlueX Project D. Cassel (chair), J. Domingo, W. Dunwoodie, D. Hitlin, G. Young. April 2001: NSAC Long Range Plan Committee. July 2003: Electronics Review of the GlueX Project J. Domingo, A. Lankford, G. Young (chair) October 2004: Detector Review M. Albrow, J. Alexander (Chair), W. Dunwoodie, B. Mecking. December 2004: Solenoid Assessment J. Alcorn, B. Kephart (Chair), C. Rode. All of these review committees have both identified areas that were unsettled and made excellent suggestions for improvements

24. Elton S. Smith University of Virginia Oct 25, 2005 24 Hall D Organizational Chart Proposal for merging GlueX collaboration with 12-GeV Upgrade Project Organization reflects the WBS outline

25. Elton S. Smith University of Virginia Oct 25, 2005 25 Summary  Mapping the spectrum of hybrid mesons provides essential experimental data on the physics of the strong interactions at low energies in the region of confinement.  This unique experimental program is possible now due to ─ increases in computational power ─ new developments in detector readout technology ─ to high quality electron beam at the 12-GeV CEBAF Upgrade ─ technology to produce thin diamond crystals  You are asked today to review the conceptual design of the Hall D tagger spectrometer and the design parameters of the photon beam for use in this experimental program.

26. Elton S. Smith University of Virginia Oct 25, 2005 26 Backup slides