CALOR 2008 Philippe Rosier – 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 GSI ~2016

CALOR 2008 Philippe Rosier – 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 FAIR Micro vertex Straw tubes (or TPC) DIRC-like Cerenkov Electromagnetic Calorimeter 1.94 m

CALOR 2008 Philippe Rosier – PANDA 2- The electromagnetic calorimeter in the target spectrometer Magnetic field 2T Photo sensors APD (Barrel) VPT (Endcap) (// beam) Barrel crystals Forward Endcap 3600 crystals Backward Endcap 592 crystals 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

CALOR 2008 Philippe Rosier – 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

CALOR 2008 Philippe Rosier – 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 Mainz

CALOR 2008 Philippe Rosier – 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

CALOR 2008 Philippe Rosier – 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 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

CALOR 2008 Philippe Rosier – 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 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

CALOR 2008 Philippe Rosier – PANDA VPT specifications external diameter 22mm overall length: 46mm or less gain: 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)

CALOR 2008 Philippe Rosier – PANDA 9-Front-end electronics: Discrete preamplifier development Four channels preamplifier mounted in the proto : 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 -25°C/ shaping time 250ns/ LAAPD (270pF) Low Power Consumption: 50 mW Time resolution 200MeV Rise time: 16ns Sensitivity 50 

CALOR 2008 Philippe Rosier – 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 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

CALOR 2008 Philippe Rosier – 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

CALOR 2008 Philippe Rosier – 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 -25°C 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)

CALOR 2008 Philippe Rosier – 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

CALOR 2008 Philippe Rosier – 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 -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

CALOR 2008 Philippe Rosier – 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: 2.1m from target

CALOR 2008 Philippe Rosier – 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 First prototype of 16 crystals for the forward Endcap

CALOR 2008 Philippe Rosier – PANDA 10- Conclusion The Electromagnetic calorimeter Technical Design Report is under construction and almost finished The mass production of the crystals will start soon Construction in : 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 Spokesperson: Ulrich Wiedner – Bochum Deputy: Paolo Gianotti - LNF