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Valery Dormenev Institute for Nuclear Problems, Minsk

Experiment PANDA. Electromagnetic calorimeter based on the improved Lead Tungstate (PbWO 4 ) crystals. Valery Dormenev Institute for Nuclear Problems, Minsk. Facility for Antiproton and Ion Research (FAIR) at GSI (Darmstadt, Germany). Double ring with 1100 m circumferences.

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Valery Dormenev Institute for Nuclear Problems, Minsk

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  1. Experiment PANDA. Electromagnetic calorimeter based on the improved Lead Tungstate (PbWO4) crystals. Valery Dormenev Institute for Nuclear Problems, Minsk Gomel, 23.07-03.08 2007

  2. Facility for Antiproton and Ion Research (FAIR) at GSI (Darmstadt, Germany) Double ring with 1100 m circumferences. Pulse intensity SIS100: 4*1013 proton per pulse at 29 GeV, 5*1011 U28+ ions per pulse at 1 GeV/u SIS300: 1.5*1010 U92+ ions per pulse at 35 GeV/u

  3. Basic Data of High Energy Storage Ring (HESR) Antiprotons/protons storage and acceleration Injection

  4. The PANDA Physics Program • Charmonium spectroscopy • Exotics: hybrids, glueballs and other exotics • Mesons in nuclear matter • Hypernuclear physics • D mesons physics

  5. Objects of research

  6. PANDA detector 2 T superconducting solenoid 2 T dipole magnet Pellet target with 4*1015 atoms/cm2

  7. PANDA electromagnetic calorimeter On lead tungstate scintillation crystals with increased light yield (PWO-II) • photon detection with • energy- • high position- resolution • time- • a wide energy range: • 10 MeV < Eg< 10 GeV • located inside a superconducting solenoid (B = 2T) • necessarycrystal size: length 20-22X0=18-20 cm, • cross section RM*RM=2.2*2.2 cm2 Total crystals number: Barrel: 11520 Endcap upstream: 816 Endcap downstream: 6864 PWO X0=0.89 cm RM=2.19 cm

  8. Lead tungstate crystal (PbWO4) CMS-type properties

  9. Properties optimization of PWO crystals for PANDA EMC To detect low energy g-quanta light yield increase is necessary There are 3 way: 1) Growth technology optimization to suppress amount of structure defects 2) Crystal activation by La, Y ions to achieve optimal Light Yield/ Kinetics/Radiation Hardness relation CMS crystals have been optimized for high radiation hardness requirement. 3) Operation at low temperature INP team activities (present and future): • Optimization of the PWO crystal growth technology CMS EMC (1992-2007) • Development of PANDA EMC specification (2002-2006) • Quality improvement (PWO-II) for PANDA (2003-2007) • Spectroscopy studies of preproduction crystals (2004-2007) • Beam tests with 3*3 and 5*5 matrix of PWO-II (2004-2008) • Development of the monitoring system for calorimeter (2005-2008) • Quality tests of PWO-II crystals for PANDA EMC (2008-2009)

  10. Performed measurements • Light Yield measurements at different temperatures and time gates to study LY and kinetics dependences • Beam test measurements of 3*3 PWO-II crystals matrix with APD read out at 00 C to evaluate energy resolution

  11. Light yield temperature dependence (1) factor 4.5 +250C -250C Time gate=4ms

  12. Light yield temperature dependence (2) Fast enoughtime response at -250C

  13. Beam test of 3*3 matrix of PWO-II crystals with Avalanche photodiodes readout (MAMI/ Mainz, Germany) 16 photon energies: 40.9-674.5 MeV, width DE ~ 2MeV Time gate=1 ms

  14. beam

  15. Energy response. Line shape. Eg=674.5 MeV Eg=40.9MeV • 8 surrounding crystals S 9 crystals S 9 crystals • 8 surrounding crystals Counts Central crystal Central crystal Energy, a.u.

  16. Energy resolution Stochastic term For CMS ECAL :

  17. Conclusions (1) • Technology optimization of PWO-II crystals gives double increase of the Light Yield in comparison with CMS PWO crystals • Cooling from +250C down -250C allows to increase the Light Yield in 4-4.5 times with 90% of the light collection in 200 ns at -250C • Energy resolution at 00C of PWO-II with APD: stochastic term 1.21% (00 C) is better then 2.3% (+180C) for CMS EMC

  18. Conclusions (2) • Extrapolation of the energy resolution of the 3x3 matrix of PWO crystals with APD readout at 00C gives s/E=2.46 % @Eg=1 GeV • Previous test results of the 3x3 matrix of PWO crystals with PMT readout at -250C gives extrapolated energy resolution s/E= 1.86% @Eg=1 GeV with 0.95 % stochastic term • Unfortunately transversal shower leakage is large at 3*3 crystals matrix geometry

  19. Future plans • PROTO60 Beam tests: 60 PWO-II crystals of the PANDA EMC geometry with APD readout at -250 C • Radiation hardness investigation at -250 C

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