1. CALOR 2008 Philippe Rosier – EMC @ PANDA The Electromagnetic Calorimeter of the future PANDA detector P. Rosier Institut de Physique Nucléaire d’Orsay (France) for the PANDA collaboration PANDA Spectrometer on FAIR @ GSI ~2016

2. CALOR 2008 Philippe Rosier – EMC @ PANDA Actual GSIHESR Central Forward Central (Target Spectrometer) 2 Tesla Solenoid Magnet FAIR : Future Facility at GSI Darmstadt, Germany HESR : antiproton storage ring 1-15 GeV/c PANDA : 4π internal target detector 1- The PANDA detector @ FAIR Micro vertex Straw tubes (or TPC) DIRC-like Cerenkov Electromagnetic Calorimeter 1.94 m

3. CALOR 2008 Philippe Rosier – EMC @ PANDA 2- The electromagnetic calorimeter in the target spectrometer Magnetic field 2T Photo sensors APD (Barrel) VPT (Endcap) (// beam) Barrel 11360 crystals Forward Endcap 3600 crystals Backward Endcap 592 crystals 15552 crystals Beam Compact geometry Nearly 4π coverage High rate capabilities Lead tungstate (PbWO 4 ) Scintillator Low Radiation length Low Moliere radius Fast response Energy From 10 MeV to 15 GeV Concept as CMS ECAL BUT … Need good energy resolution

4. CALOR 2008 Philippe Rosier – EMC @ PANDA 3- General R&D to improve the efficiency Improve the light output of the PbWO4 by : 3-Improving the radiation hardness 1-Improving the quality (light yield and optical transmission) 2-CooIing down the crystals down to -25°C R&D on the front-end electronics Low noise and low thermal consumption Improve the signal output from the photo sensors (large APD and VPT) Mechanical concept Cooling design at -25°C STABILIZATION at +/-0.1°C (temp. dependency) Present activities : Irradiation studies (Bonn, Giessen, Protvino) APD selection/screening Front-End electronics development Operation of PROTO60 Detailed design of the barrel and forward endcap

5. CALOR 2008 Philippe Rosier – EMC @ PANDA 4- Optimization of the PbWO4 and increase of the light output 4x lighter if cooled down +80% at room T° Development of the PWO-II : Light yield increased Optimization of the PbWO 4 (collaboration RINP, Minsk and the manufacturer BTCP at Bogoroditsk, Russia) – reduction of defects (oxygen vacancies) – reduced concentration of La-, Y-Doping – better selection of raw material – optimization of production technology 3x3 matrix 20x20x200mm 3 PM-readout Response to high energy photons @MAMI, Mainz

6. CALOR 2008 Philippe Rosier – EMC @ PANDA 5- Radiation hardness studies at low temperature Several irradiation benches (Bonn, Giessen, Protvino) cooling machine  -source crystal container Measurement of the decrease of optical transmission with  (at room T° due the linearity with low T°) Around 25% of decrease (preliminary measure) PMT output / a.u time / h recovery at +20 o C recovery at -25 o C The recovery time is faster at room temperature

7. CALOR 2008 Philippe Rosier – EMC @ PANDA 6- Recovery processes Recovery processes not fully understood Quantitative analysis of defect centers via EPR (MoO 4 ) 3- center : reflects the loss of optical transmission Recovery 25% / 4 days @ T = -25 o C => Monitoring Radiation resistance of 30 crystals produced most recently  Induced absorption coefficient <1m -1 The mass production is feasible and the crystal specifications: radiation hardness light yield will be well beyond the CMS quality

8. CALOR 2008 Philippe Rosier – EMC @ PANDA Based on the CMS experiment, and in collaboration with Hamamatsu Photonics R&D on Large Area Avalanche Photo Diode to be implemented in the barrel CMS 5x5mm 2 10x10mm 2 PANDA Excellent performance – at RT and T = –25°C Radiation resistant – up to 10 13 protons – in particular at T = -25°C – Tests with proton neutrons photons Nuclear counter effect not significant 7- Large Avalanche Photo Diodes (Barrel) Rectangular LAAPDs (prototype available mid 2008) 2 x to achieve 27 % of readout area and for redundancy PANDA II 7x14mm 2 PIN diode Cooling pipes HV / Signal cables APD holder In a dry nitrogen flooded light tight box APD screening equipment

9. CALOR 2008 Philippe Rosier – EMC @ PANDA VPT specifications external diameter 22mm overall length: 46mm or less gain: 10-30 or more quantum efficiency: > 20% operational temperature range: -30 C to 35 C rate capability >500 kHz Possible suppliers Photonis – Q.E. improved (above 30%) – Gain RIE (default) – Photo-Tetrode – CMS experience Hamamatsu ? 8-Vacuum Photo Triodes (Forward Endcap) Hit rates simulation in the forward endcap R&D on the VPTs for the forward endcap (// magnetic field)

10. CALOR 2008 Philippe Rosier – EMC @ PANDA 9-Front-end electronics: Discrete preamplifier development Four channels preamplifier mounted in the proto 60 2006: SP883-quad 2004: SP883-single => adapted recently to readout the forward endcap Since 2004, R&D on low noise preamplifier with discrete components. Development of a single preamplifier - Construction of a “quad preamplifier” The existing preamplifier works with: Low noise: 1600e rms @ -25°C/ shaping time 250ns/ LAAPD (270pF) Low Power Consumption: 50 mW Time resolution 200MeV Rise time: 16ns Sensitivity 0.5V/pC @ 50 

11. CALOR 2008 Philippe Rosier – EMC @ PANDA PCB for tests first chip prototype One channel preamplifer For the APD readout of the barrel: R&D on an ASIC Charge preamplifier Requirements for first prototype – Large dynamic range: 1 MeV – 5 GeV – Low noise – Low consumption device @ T = -25° C 10-Front-end electronics: ASIC development Channel 1 Channel 2 DAC 1DAC 2 New ASIC for 2 channels which shows good performance  42 mW per channel Charge sensitive preamplifier : 10 mW Shaper (integrator): 15 mW Differential output driver Buffer: 17 mW Power Consumption Simulation Results

12. CALOR 2008 Philippe Rosier – EMC @ PANDA 11- Design of the barrel and R&D on composites Longueur 2.5 m Rayon 0.57 m Barrel slice (1/16) 710 crystals 11 crystal types Alveoles Aluminum insert Crystals Carbon fiber alveole (transparency/rigidity) Loading tests and simulations Upper thermal screen

13. CALOR 2008 Philippe Rosier – EMC @ PANDA 12- Thermo-mechanical design for the low temperature Simulations to define the APD-preamplifier link BF862 Δ+4°C APD connector Δ+2.5°C AD8011 Δ+3°C Preliminary temperature simulation (50mW) Quad preamplifier Vacuum panel Carbon @ -25°C Aluminum @ 20°CRohacell Super- insulation R&D Front thermal screen Cooling at -25°C stabilized at +/-0.1°C 5 %/°C temperature dependency of the crystal-APD Thermal expansion (mechanical design) Dry atmosphere to avoid moisture or ice Need low thermal consumption electronics Good thermal screen (low thickness in front) Thermo-mechanical design (thermal bridges)

14. CALOR 2008 Philippe Rosier – EMC @ PANDA 13- Prototype 60 crystals Crystals by 4 Inserts and carbon alveoles Back view of the proto 60 Final mounting: with the optical fibers for laser calibration Barrel prototype type 6: full scale representative part of one slice Insulated sealed box with thermal screens Back PCB Bottom mechanical support

15. CALOR 2008 Philippe Rosier – EMC @ PANDA ChillerDAQ rack High voltage supply Beam test in July 2008 Nitrogen flowing 14- First tests with the 60 crystals prototype Cosmic rays measured during calibration @ -25°C Temperature measurement over 24 hours: Crystals stability +/-0.05°C Ambient air: +/-2°C Crystals sensors: +/-0.05°C Chiller: +/-0.01°C

16. CALOR 2008 Philippe Rosier – EMC @ PANDA Integration of the thermo-mechanical design 15- Forward Endcap Geometry made of 3600 identical crystals The forward endcap concept in the target spectrometer Radius: 0.92m @ 2.1m from target

17. CALOR 2008 Philippe Rosier – EMC @ PANDA 16 crystals, surrounded by 48 dummies for strength and stiffness tests Thermo mechanical tests Carbon fiber alveoles production (industrial Fiberworkx BV, Groningen) Mounting tests photon response tests in 2008 9- First prototype of 16 crystals for the forward Endcap

18. CALOR 2008 Philippe Rosier – EMC @ PANDA 10- Conclusion The Electromagnetic calorimeter Technical Design Report is under construction and almost finished The mass production of the 15552 crystals will start soon Construction in 2009-2010: 1- A barrel slice prototype of 710 crystals 2- A forward endcap prototype of 192 crystals (used as spare modules) Phase 1 of the PANDA physics program for 2014 http://www-panda.gsi.de Spokesperson: Ulrich Wiedner – Bochum Deputy: Paolo Gianotti - LNF