Overview Bremsstrahlung Tagging Spectrometer and Photon Beam Review

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

Physics goals and key features Normal mesons: glue is passive Hybrid mesons: glue is excited The physics goal of Glue. X is to map the spectrum of hybrid mesons starting with those with the unique signature of exotic JPC. Identifying JPC 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 Ge. V, requires 9 Ge. V photons produced using coherent bremsstrahlung from 12 Ge. V electrons. Elton S. Smith University of Virginia Oct 25, 2005 2

Search for QCD Exotics The Glue. X Detector Design has been driven by the need to carry out Amplitude analysis. , K, b 2 h’ 2 b 0 h’ 0 1−+ 2+− 0+− 1 → a+1 - → ( o +)( -) → + - X p 1 1 ’ 1 all charged h 0 → bo 1 o → ( o) → + - n, p many photons Photoproduction h’ 2 → K+1 K− → o K+ K− → + −K+K− strange particles Final state particles Elton S. Smith ± K ± p University of Virginia n KL Oct 25, 2005 3

Mass Predictions Lowest mass expected to be 1(1−+) at 1. 9± 0. 2 Ge. V Lattice 1 -+ 1. 9 Ge. V 2+- 2. 1 Ge. V 0+- 2. 3 Ge. V Elton S. Smith University of Virginia Oct 25, 2005 4

Line shape distortion M=2. 5 Ge. V M=2. 8 Ge. V MX (Ge. V) Elton S. Smith University of Virginia Oct 25, 2005 5

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

Strategy for Exotic Meson Discovery § Use 8 – 9 Ge. V polarized photons (12 Ge. V electron beam) ─ Sensitivity to mesons masses up to 2. 5 Ge. V ─ 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 Elton S. Smith University of Virginia Oct 25, 2005 7

Requirements for photon beam § Coherent peak ~ 8. 4 ─ 9 Ge. V § Linear polarization § High rates ─ Initial running at 107 /s in the coherent peak ─ Design system with a clear path to 108 /s Elton S. Smith University of Virginia Oct 25, 2005 8

add Hall D (and beam line) 126 Ge. V CEBAF Upgrade magnets and power supplies CHL-2 Enhance equipment in existing halls Elton S. Smith University of Virginia Oct 25, 2005 9

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

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

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

Glue. X detector Capability Quantity Range Charged particles Coverage 1 o < q < 170 o Momentum Resolution (5 o-140 o) sp/p = 1 − 2% Position resolution s = 150 -200 mm d. E/dx measurements 20 < q < 140 o Time-of-flight measurements st = 60 ps Cerenkov and /K separation q < 14 o Barrel time resolution st < (150 + 50 /√E) ps Energy measurements 2 < q < 120 o Veto capability q > 120 o Barrel energy resolution (E > 20 Me. V) s. E/E = (2 + 5/√E)% Lead glass energy resolution (E > 100 Me. V) s. E/E = (3. 6 + 7. 3/√E)% Barrel position resolution sz ~ 4 cm Lead glass position resolution sx, y = 0. 7 cm Level 1 200 k. Hz at 108 /s Level 3 event rate to tape 15 k. Hz Data rate 100 MB/s Electronics Fully pipeline Flash ADCs, multi-hit TDCs Photon Flux Tagged rate Initially: 107 /s, Final: up to 108 /s Photon detection DAQ/trigger Elton S. Smith University of Virginia Oct 25, 2005 13

Institutional Responsibilities The Glue. X 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. • Solenoid JLab • Detectors • Tracking • Calorimetry Carnegie Mellon, Ohio U, Florida International U • PID U of Regina, Florida State, Indiana U, Inst for High Energy Physics (Protvino), U of Athens 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 • Beamline • Infrastructure Indiana U, JLab, U of Alberta, Indiana U Cyclotron Catholic U of America, Glasgow U, U of Connecticut JLab Elton S. Smith University of Virginia Oct 25, 2005 14

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 Ge. V 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 Glue. X detector. Elton S. Smith University of Virginia Oct 25, 2005 15

Coherent Bremsstrahlung This technique provides requisite energy, flux and polarization flux 12 Ge. V electrons Incoherent & coherent spectrum 40% polarization in peak photons out collimated electrons in spectrometer diamond crystal Hadronic Backgrounds Elton S. Smith tagged photon energy (Ge. V) 0. 1% resolution University of Virginia Oct 25, 2005 16

High sensitivity → high rates Start with 8. 4 - 9. 0 Ge. V Tagged 30 cm target cross section = 120 µb low-rate high-rates: multiply by factor of 10 Elton S. Smith University of Virginia Oct 25, 2005 17

Photon Beam Rates and Backgrounds 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 12 Ge. V electron beam energy. peak energy N in peak polarization (f. w. h. m. ) 8 Ge. V 9 Ge. V 10 Ge. V 11 Ge. V 185 M/s 100 M/s 45 M/s 15 M/s 0. 41 0. 27 0. 11 (900 Me. V) (600 Me. V) (240 Me. V) 0. 54 (1140 Me. V) peak tagging eff. (f. w. h. m. ) 0. 55 0. 50 0. 45 0. 29 (720 Me. V) (600 Me. V) (420 Me. V) (300 Me. V) total hadronic rate (in tagged peak) 385 K/s (26 K/s) 365 K/s (14 K/s) 350 K/s (6. 3 K/s) 345 K/s (2. 1 K/s) Elton S. Smith University of Virginia Oct 25, 2005 18

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

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

JLab 12 Ge. V Upgrade Project Status Highlight in the 20 -year plan of the Office of Science (2003) What’s New: “New supercomputing studies indicate that force fields called “fluxtubes” 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) Review of Science program for the 12 -Ge. V 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…” Successful Project Review (Jul 2005), CD-1 expected soon Four-year construction project planned to start in FY 08 Elton S. Smith University of Virginia Oct 25, 2005 22

Glue. X Reviews December 1999: PAC Requested Review of the Glue. X 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 Glue. X 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 Elton S. Smith University of Virginia Oct 25, 2005 23

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

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 -Ge. V 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. Elton S. Smith University of Virginia Oct 25, 2005 25