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Photon physics at JLab: Status and prospects 2007-20??

Photon physics at JLab: Status and prospects 2007-20??. Daniel Sober The Catholic University of America. Outline. Jefferson Lab and Hall B Completed CLAS runs Future CLAS runs PRIMEX (Hall B Primakoff experiment) Hall D and GlueX Photon physics with CLAS12.

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Photon physics at JLab: Status and prospects 2007-20??

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  1. Photon physics at JLab:Status and prospects2007-20?? Daniel Sober The Catholic University of America CB@MAMI Collaboration Meeting

  2. Outline • Jefferson Lab and Hall B • Completed CLAS runs • Future CLAS runs • PRIMEX (Hall B Primakoff experiment) • Hall D and GlueX • Photon physics with CLAS12 CB@MAMI Collaboration Meeting

  3. The Thomas Jefferson National Accelerator Facility (JLab) • 5-pass recirculating linear accelerator • Maximum energy currently ~5.2 GeV (Planned: ~5.7 GeV by 11/07, ~6.0 GeV by 10/08, ~6.5 GeV by 6/09) • 3 experimental halls • Tagged photon facility in Hall B CB@MAMI Collaboration Meeting

  4. The CLAS detector Polarized electron and tagged photon beams Cryogenic and polarized targets Hall B CB@MAMI Collaboration Meeting

  5. The CEBAF Large Acceptance Spectrometer (CLAS) in Hall B Performance • L = 1034 cm-2 s-1 •  B dl = 2.5 T m • Dp/p ~ 0.5-1 % • ~ 4p acceptance • Best suited for multiparticle final states • Bremsstrahlung Photon Tagger (DEg/Eg~10-3) CB@MAMI Collaboration Meeting

  6. Hall B Tagged Photon system CB@MAMI Collaboration Meeting

  7. Recently completed photon run periods Run E0 Photon Target Reactions period (GeV) Pol. • 2004 g10 3.77 circ. LD2 pentaquark search, [KL, KS] g11 4.02 circ. LH2 pentaquark search, [KL, KS] PRIMEX 5.75 - C, Pb p0 lifetime by Primakoff effect (non-CLAS) • 2005 eg3 5.75 circ. LH2 exotic cascade search g8b 4.05 linear LH2 rp, fp, wp [hp, h‘p, p0p, p+n] • 2006 TPE test 3.29 g→e+,e- 2-photon exchange: Simultaneous e+ and e- scattering • 2007 g13 several linear LD2 gn→KL, KS, 1.1 to 2.3 GeV [p0p, p+n] CB@MAMI Collaboration Meeting

  8. g8b status report - June 2007 Overview • Linearly polarized photon beam to measure photon asymmetries and double polarization observables • Beamtime from June 26th – Aug 31st 2005 • Lin. Pol. photons on 40cm LH2 target • 5 coherent peak positions from 1.3 -> 2.1 GeV • Polarization in excess of 90% achieved • 10 billion events CB@MAMI Collaboration Meeting

  9. g8b status report - June 2007 Analysis in progress • production(spin density matrix elements) • (Idaho State University) • f - production(spin density matrix elements) • (Idaho State University) • production • (Catholic University of America) • production(Single and double pol. observables) • (Glasgow University) • h, h’production (beam asymmetry) • (Arizona State University) • p+n, p0p production (beam asymmetry) • (Arizona State University) CB@MAMI Collaboration Meeting

  10. g8b status report - June 2007 Preliminary analysis (ASU): gp -> pp0 CB@MAMI Collaboration Meeting

  11. g13 status (ended June 30)g(linear) + LD2: gn → KS, KL, ... 6 coherent peak settings: 1.1 – 1.3 GeV (E0 = 3.3, 3.9, 4.2 GeV) 1.3 – 1.5 GeV (E0 = 4.5 GeV) 1.5 – 1.7 GeV (E0 = 4.7 GeV) 1.7 – 1.9 GeV (E0 = 5.1 GeV) 1.9 – 2.1 GeV (E0 = 5.2 GeV) 2.1 – 2.3 GeV (E0 = 5.2 GeV) CB@MAMI Collaboration Meeting

  12. g13: Yields for  n → K0 LX • Top: invariant mass of pp- near m(L) • Bottom: invariant mass of p+p- near m(K0) • Left: no cuts • Right: cuts on the other particle • Plots show a 5 GeV run with the coh. edge at 1.9 GeV CB@MAMI Collaboration Meeting

  13. g13 analysis: gn→p-p CB@MAMI Collaboration Meeting

  14. TPE (Two-photon exchange) - Beyond the Born Approximation e+p→e+p / e-p→e-p 1 mAon 5% radiator CB@MAMI Collaboration Meeting

  15. Necessary Tagger Modifications for TPE CB@MAMI Collaboration Meeting

  16. The PrimEx ExperimentA. Gasparian et al. (NCA&T, Kentucky, UMass, MIT, … • Precision measurement of p0lifetime using Primakoff effect: g+ gV (nuclear target) → p0 (→g + g ) -- one of the few quantities in the confinement region that QCD can calculate precisely • Hall B tagger + “HyCal” (dedicated hybrid calorimeter: PbW04 inner detector, lead glass outer detector) • Separate Primakoff from nuclear p0production by angular distribution. • Require absolute cross section – check normalization by measurements of Compton scattering and pair production • Preliminary results presented at April 2007 APS meeting CB@MAMI Collaboration Meeting

  17. PrimEx Approach Primakoff effect PrimEx improvements: • JLab Hall B high resolution high intensity photon tagging facility • New novel high resolution, high acceptance multi-channel calorimeter (HYCAL) CB@MAMI Collaboration Meeting

  18. PrimEx Hybrid Calorimeter - HyCal • Optimize performance and cost Hybrid calorimeter: • 1152 PbWO4 novel crystal detectors; • 576 Pb-glass Cherenkov detectors CB@MAMI Collaboration Meeting

  19. Fit to Extract 0 Decay Width Primakoff Coherent Incoherent • Combined average from three independent analysis groups: Γ(0) 7.93 eV  2.10%(stat.) Interference CB@MAMI Collaboration Meeting

  20. PrimEx Preliminary Result • PrimEx Preliminary Result: (0) = 7.93eV2.1%(stat)2.0%(syst) Most recent calculation of hadronic correction in QCD by Ioffe & Oganesian, hep-ph/0701077 gives: (0) = 7.93eV ± 1.5% (uncertainty from hdue to p0/h mixing) (0) = 7.93eV2.1%2.0% CB@MAMI Collaboration Meeting

  21. PrimEx Future Plans • Publish existing results • New 6 GeV run to obtain proposed 1% statistics • 12 GeV proposal: p0,h, h’ gg widths and transition form factor CB@MAMI Collaboration Meeting

  22. Future CLAS photon run periods Run E0 Photon Target Reactions period (GeV) Pol. • 2007 g9a 1.8– circ., Longit.Missing resonances in (FROST) 4.0 linearPol. HpN,KL,KS, hp, p+p-p • 2008 g12>5.7circ.LH2Exotic mesons and baryons • 2009–2011 g9bVarious circ., Longit.&Missing resonances in (FROST) linearTransv.pN, KL,KS, hp, p+p-p Pol. H g16Variouscirc., Polarizedgn→p0p, p+p-n, linearHDK0L, K0S0, K+S- CB@MAMI Collaboration Meeting

  23. target: Ø15mm x 50mm butanol C4H9OH dilution factor 10/74 eff. density: 0.611 g/cm3 CLAS Frozen-Spin Target (FROST) operate at ~50mK, repolarize at 0.4K CB@MAMI Collaboration Meeting

  24. CLAS-FROST: g→p0p, p+n (sample PWA) Sample PWA data generated from SAID SM02 (Recoil, Target asy., all 4 Beam-Target asymmetries) red: predicted FROST data greatly reduced uncertainties 1=uncertainty based on world data CB@MAMI Collaboration Meeting

  25. FROST outlook • 1st run period in fall 2007 (long.pol.) • Recent tests successful (20 mW at 200 mK, 100 mW at 50 mK – June 2007) • All polarization observables measurable in CLAS will be extracted from data • Complete set of measurements for KY • “Almost” complete set for pN, hp • Double/triple pol. obs. for p+p-p, wp minimally model-dependent extraction of N* parameters & potential for discovery of missing states CB@MAMI Collaboration Meeting

  26. HD Target (“HD-ICE”) • Previous operation at LEGS (BNL) • DOE funding approved: A. Sandorfi and group will move to JLab in early 2008 • New horizontal cryostat required for CLAS • Aim for 2009 installation and run CB@MAMI Collaboration Meeting

  27. HD target target: Ø25mm x 50mm 3g of solid H-D composite density: 0.147 g/cm3 2050 cooling wires (Al) Ø50mm PV(D)~40%, P(H)~40% or PV(D)~0%, P(H)~80% In-Beam-Cryostat for CLAS LEGS data: CB@MAMI Collaboration Meeting

  28. E06-101:+ frozen-spinin CLAS • high nucleon polarizations • in-beam lifetimes > year  n(p) 0 0 (p)  +–p–( p) MM2 (+D) • • clean channel-separation; • very low backgrounds • factors of > 20 reduction in beam-time over other targets  n(p) 0 (p)  +–p–(p) MM2 (+n) CB@MAMI Collaboration Meeting

  29. Summary of Frozen-Spin Experimental Program polarized butanol target (89 days of beam time) • E02-112: gp→KY(K+L, K+S0, K0S+) • E03-105/E04-102: gp→p0p, p+n • E05-012: gp→hp • E06-013: gp→p+p-p polarized HD target (85 days) • E06-101: gn→πp-p,gn→p+p-n, gn→KY(K0L, K0S0, K+S-) CB@MAMI Collaboration Meeting

  30. Upgrade magnets and power supplies CHL-2 Enhance equipment in existing halls Add new hall 12 11 6 GeV CEBAF CB@MAMI Collaboration Meeting

  31. Upgrade Beam Properties All polarized ! CB@MAMI Collaboration Meeting

  32. The 12 GeV Upgrade: Complementary Equipment in Halls B & C, and a New Hall D C D 9 GeV tagged polarized photons and a 4 hermetic detector Super High Momentum Spectrometer (SHMS) at high luminosity and forward angles A B Retain HRS Pair for continuation of research in which resolution comparable to nuclear level spacing is essential. Use Hall to stage “one-of-a-kind” specialized experiments requiring uniqueapparatus. CLAS upgraded to higher (1035 cm-2s-1) luminosity and coverage CB@MAMI Collaboration Meeting

  33. Photon physics after the 12 GeV upgrade (2012+) • Hall D: The GlueX experiment Dedicated coherent bremsstrahlung beam. Search for exotic mesons at Eg> 9 GeV • Hall B: CLAS-12 No planned tagger upgrade in base equipment. New torus magnet and detectors, emphasizing forward acceptance, electron beam experiments (GPDs) CB@MAMI Collaboration Meeting

  34. Hall D (GlueX): Research Program • Search for Gluonic Excitations • Hybrid (qqg) spectrum expected between 1.5 and 2.5 GeV/c2 • Exotics do not mix with normal qq mesons • ALSO: • ss spectroscopy • Only five states established • Photon has a large virtual (ss) component • Other physics • KK threshold • Radiative decays of excited vector mesons - - CB@MAMI Collaboration Meeting

  35. Photoproduction More likely to find exotic hybrid mesons using beams of photons. Lowest-mass hybrids predicted to be in JPC=1-+ nonet. Photon linear polarization constrains the production mechanism. CB@MAMI Collaboration Meeting

  36. Ideal Photon Beam Energy for GlueX • Based on: • maintain sufficient photon flux/polarization (via coherent bremsstrahlung) • maintain sufficient meson yield for high mass (2.5 GeV) region • separate baryon from meson resonances Figure-of-merit (P2 x Ng) for M = 2.5 GeV and E0 = 12 GeV CB@MAMI Collaboration Meeting

  37. Photon beam and experimental area Tagger area Hall D North linac Electron Beam dump East arc Photon Beam dump 75 m Solenoid- Based detector Electron beam Collimator Tagger Area Coherent Bremsstrahlung photon beam Experimental Hall D Top View CB@MAMI Collaboration Meeting

  38. GlueX Detector in Hall D Hermetic detection of charged and neutral particles Tagger Spectrometer (Upstream) CB@MAMI Collaboration Meeting

  39. CB@MAMI Collaboration Meeting

  40. CB@MAMI Collaboration Meeting

  41. Hall-D tagger • two-magnet design with horizontal deflection • hodoscope: variable ‘microscope’ & coarse fixed array • photon spectrum: coherent and incoherent bremsstrahlung primary e-beam deflected e-beam CB@MAMI Collaboration Meeting

  42. CB@MAMI Collaboration Meeting

  43. CB@MAMI Collaboration Meeting

  44. CLAS12– 12 GeV Upgrade of Hall B • Hall B with CLAS12 is a major part of the upgrade to 12 GeV • PAC30 recommended approval of a broad initial physics program. • Many components are in R&D or design phases: Drift chambers, SVT, calorimeter, Cerenkov counter, TOF counters, s.c. magnets. • CD-2 review in summer 2007. CLAS12 CB@MAMI Collaboration Meeting

  45. Future of the Hall B Tagger • Maximum E0 = 6.2 GeV at I = 2400 A • At 12 GeV operation, Hall B will have choice of 2.2, 4.4, 6.6, 8.8, 11 GeV. • Desirable to raise tagger capability to 6.6 GeV: new power supply, add yoke iron? • More speculative: Dump electrons in tagger yoke? (background test July 2007). • New end-point tagger under consideration – no detailed design, no funds in initial upgrade. CB@MAMI Collaboration Meeting

  46. Summary • 2007-2011 Intensive program in N* photoproduction using polarized beams and frozen-spin polarized targets (butanol and HD) in Hall B. • After the 12 GeV upgrade: Exotic meson (gluonic excitations) program in Hall D. Future of photon physics in Hall B is uncertain. CB@MAMI Collaboration Meeting

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