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High Performance PbWO 4 - Lead Glass Hybrid Calorimeter at Jefferson Lab

High Performance PbWO 4 - Lead Glass Hybrid Calorimeter at Jefferson Lab. M. Kubantsev ITEP, Moscow, Russia/Northwestern University, Evanston, USA A. Gasparian NC A&T State University Greensboro, NC USA I.Larin ITEP, Moscow,Russia for the PrimEx Collaboration. Outline

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High Performance PbWO 4 - Lead Glass Hybrid Calorimeter at Jefferson Lab

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  1. High Performance PbWO4- Lead Glass Hybrid Calorimeter at Jefferson Lab M. Kubantsev ITEP, Moscow, Russia/Northwestern University, Evanston, USA A. Gasparian NC A&T State University Greensboro, NC USA I.Larin ITEP, Moscow,Russia for the PrimEx Collaboration • Outline • Requirements for the Calorimeter • The HYCAL calorimeter design • Physics run performance • Summary.

  2. Requirements for the Calorimeter • Forward electro-photoproduction of neutral mesons (o ) • @ 1- 10 GeV requires: • High energy resolution; • High position resolution; • Good photon detection efficiency @ few GeV; • Large geometrical acceptance. (Pr)peak 0.3 mrad o life-time measurement at JLab (the PrimEx experiment E-02-103): M.Kubantsev ITEP/NWU

  3. Design Concept and Resolutions  Invariant Mass Resolution Angular Resolution M.Kubantsev ITEP/NWU

  4. Design Concept Resolution + Budget PbWO4 crystalPb – glass Cherenkov Detectorsdetectors M.Kubantsev ITEP/NWU

  5. Design Concept HYCAL with veto Modules: PWO: 34x34–4 = 1152 LG: 4x6x24 = 576 M.Kubantsev ITEP/NWU

  6. PbWO4 Crystal Dimensions Tolerances (mm): 20.5 + 0.0 - 0.1 180.0 + 0.3 -0.0 Dimensions: 20.5 x 20.5 x 180.0 mm3 Specified Measured M.Kubantsev ITEP/NWU

  7. PbWO4 Crystal Optical Properties Optical Transparency @ 360 nm @ 420 nm M.Kubantsev ITEP/NWU

  8. HYCAL – The Hybrid Calorimeter Detector assembly and preparation tests M.Kubantsev ITEP/NWU

  9. HYCAL Calibration Scheme of calorimeter irradiation with tagged photon beam during calibration M.Kubantsev ITEP/NWU

  10. HYCAL Energy Resolution PWO LG a = 0.009 b = 0.025 c = 0.010 a = 0.023 b = 0.054 c =0.0 Energy resolution for the PWO crystal central part and lead glass periphery for tagged photons during calibration run M.Kubantsev ITEP/NWU

  11. HYCAL Energy Resolution Eγ =~5 GeV M.Kubantsev ITEP/NWU

  12. HYCAL Position Resolution LG: Dx = 4 mm @ 1-3 GeV PWO: Dx =2.2 mm @ 1-3 GeV M.Kubantsev ITEP/NWU

  13. HYCAL Light Monitoring Light monitoring system with blue LED: stability over period of 500 hours M.Kubantsev ITEP/NWU

  14. HYCAL Performance for Physics Processes: LG LG Scattered Electron Photon Incident Tagged Photon Incident Tagged Photon PWO PWO Target: γe eγ Target: π0 γγ Scattered Photon Photon LG LG • π0 production and decay to two photons at all angles (PWO and LG): • constraint on mass of π0 • comparison of regions of the HYCAL: PWO, LG, PWO-LG border • Compton scattering at small angles mostly (only PWO): • Pt = 0 constraint • angular correlations as • additional check of resolution M.Kubantsev ITEP/NWU

  15. HYCAL Resolution for Compton Events: Ratio of sum of electron and photonenergies measured in the calorimeter and tagged γ energy at ~5.2 GeV σ = 1.5 % σ = 1.1 % σ = 1.7 % Events/0.001 σ after calibration after Pt = 0 correction only coordinate information M.Kubantsev ITEP/NWU

  16. HYCAL π0 Resolution: PWO σ = 2.3 MeV/c2 σ = 1.3 MeV/c2 Events/0.5 Mev/C2 Mγγ, GeV/c2 after correction on tagged photon energy: smearing due to coordinate resolution after calibration M.Kubantsev ITEP/NWU

  17. HYCAL π0 Resolution: PWO-LG Border σ = 1.4 MeV/c2 σ = 2.6 MeV/c2 Events/0.5 Mev/C2 after correction on tagged photon energy: smearing due to coordinate resolution π0 mass resolution after calibration: one photon in PWO another at the border Mγγ, GeV/c2 M.Kubantsev ITEP/NWU

  18. HYCAL π0 Resolution: PWO + LG σ = 4.5 MeV/c2 σ = 2.4 MeV/c2 Events/0.5 Mev/C2 after correction on tagged photon energy: smearing due to coordinate resolution π0 mass resolution after calibration: one photon in PWO another in LG Mγγ, GeV/c2 M.Kubantsev ITEP/NWU

  19. o Angular Distribution(experiment, preliminary) 12C 208Pb Preliminary Primakoff 0 Primakoff 0 M.Kubantsev ITEP/NWU

  20. Summary • A high performancehybrid PbWO4 calorimeter(~2000 channels) has been developed, constructedand run in PrimEx experiment at JLab. • HYCAL took physics data in November 2004: • Energy and position calibration with tagged photons of 1 – 5.5 GeV • π0 mass resolution π0 = 2.3 MeV (PWO), (with energy constraint on the tagger 1.3 MeV) • Rich high quality data sets have been collected to extract π0 life time • We expect first physics results this summer: http://www.jlab.org/primex/ • This project is supported by the US NSF MRI grant (PHY-0079840) • This project is supported by the RFBR Grant 04-02-17466 M.Kubantsev ITEP/NWU

  21. Spare slides M.Kubantsev ITEP/NWU

  22. PbWO4 Detector Response vs. Dose Rate M.Kubantsev ITEP/NWU

  23. HYCAL Position Resolution Center-of-Gravity Logarithmic Profile1 Profile2 Y beam coordinate (y = 300.88 mm) Reconstruction of photon positions in the transition region between PWO crystal central part and lead glass periphery M.Kubantsev ITEP/NWU

  24. HYCAL Position Resolution Coordinate of the cluster: Xc= Σ(xiwi)/Σwi Center-of-Gravity: Wi = Ei Logarithmic: Wi = 4.2 + ln(Ei/E9) M.Kubantsev ITEP/NWU

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