10 September 2010 Immanuel Gfall (HEPHY Vienna) Belle II SVD Upgrade, Mechanics and Cooling OEPG/FAKT Meeting 2010

Belle II SVD Upgrade, Mechanics and Cooling SuperKEKB / Belle II 2Immanuel Gfall (HEPHY Vienna)10 September 2010 e + -e - collider at Tsukuba, Japan 8 GeV e -, 3.5 GeV e + Design luminosity: 8 x cm -2 s -1 3 km perimeter Silicon Vertex Detector/ Pixel Detector Muon Detector Endcap Particle ID Central Drift Chamber Belle II: Precision CPV measurements of B decays Major upgrades in Belle II: Pixel Detector (PXD), Silicon Vertex Detector (SVD) HEPHY provides complete SVD

Belle II SVD Upgrade, Mechanics and Cooling 3Immanuel Gfall (HEPHY Vienna)10 September 2010 Belle II SVD Origami Concept APV25 sit on top of sensor High signal to noise ratio APV alignment requires only one cooling tube per ladder Fanouts connect bottom strips to APV µm thick double sided silicon sensors are read out with APV25 chips mm 56 mm

Belle II SVD Upgrade, Mechanics and Cooling 4Immanuel Gfall (HEPHY Vienna)10 September 2010 Support Structure Draft 2 Carbon fiber reinforced plastic sandwich ribs support sensors Airex core is sandwiched by one 64µm unidirectional carbon fiber layer (UD CF) on each side Aircraft grade epoxy is used as matrix Ribs are glued to surface of the Origami sensor Cooling Pipe Sensor Support Ribs Origami Fanouts Mounting Points

Belle II SVD Upgrade, Mechanics and Cooling 5Immanuel Gfall (HEPHY Vienna)10 September 20105Immanuel Gfall (HEPHY Vienna) Simulation Results Top loaded Max sag: µm Side loaded Max sag: µm Side Loaded Top Loaded Conclusion: Simulation shows that the support meets the requirements

Belle II SVD Upgrade, Mechanics and Cooling 6Immanuel Gfall (HEPHY Vienna)10 September 2010 Radiation Length 6Immanuel Gfall (HEPHY Vienna) Cooling Pipe APV25 Sensor Support Structure

Belle II SVD Upgrade, Mechanics and Cooling 7Immanuel Gfall (HEPHY Vienna)10 September 20107Immanuel Gfall (HEPHY Vienna) Carbon Fiber Sandwich Airex Core Carbon Fiber (CFRP) Mounting Points Airex core has a thickness of 3 mm High modulus carbon fiber (CF) layer is 64 µm thick 1 layer of CF on each side Strength results from the combination of core thickness and fiber strength Reinforcements

Belle II SVD Upgrade, Mechanics and Cooling 8Immanuel Gfall (HEPHY Vienna)10 September 2010 Current Ladder 6 Design The ladder is 645 mm long with a distance between the ribs of 16.5 mm Ribs are attached to end ring mounts End ring mounts also connect hybrid boards to cooling channels integrated in the end rings APV25 aligned in one line Slanted / wedge sensor in the forward region to minimize sensor count and material budget 8Immanuel Gfall (HEPHY Vienna) Sensor CF Ribs Mount Structure Hybrid Board Origami Modules Origami Modules Sensor without Origami Wedge Sensor

Belle II SVD Upgrade, Mechanics and Cooling 9Immanuel Gfall (HEPHY Vienna)10 September 2010 Construction Ladder 5 Goal: fast and cost effective production offering reproducible quality Production method used: vacuum bagging Prototyping process can be up scaled for final production Airex Core Vacuum Bag UD Carbon Fiber Vacuum Valve 2 nd Layer

Belle II SVD Upgrade, Mechanics and Cooling Cooling Power dissipation/APV: 0.4 W 1 Origami sensor features 10 APVs Total Origami power dissipation: 356 W 404 W dissipated at the hybridboards Total SVD power dissipation: 760 W Origamis /Ladder LaddersAPVs Origami APVs Hybrid Layer Layer Layer Layer Immanuel Gfall (HEPHY Vienna) APV25 Cooling Tube

Belle II SVD Upgrade, Mechanics and Cooling Cooling Requirements Smallest possible material budget in the acceptance region Operating -20°C for SNR improvement Significant part of the heat is dissipated at preamp/shaper of APV25 Radiation hard coolant Cooling system needs to handle 1kW+ of dissipated heat (including PXD) Cooling fluid should be dielectric, non-flammable and non corrosive Immanuel Gfall (HEPHY Vienna)10 September

Belle II SVD Upgrade, Mechanics and Cooling Cooling: CO2 Blow System 12Immanuel Gfall (HEPHY Vienna)10 September 2010 T=23°C P=57bar T=-20°C P=57bar T=-20°C P=20bar

Belle II SVD Upgrade, Mechanics and Cooling Summary Designs of layer 4,5 and 6 are finished Simulation results look promising First “hands on” test results are satisfactory CO 2 cooling is the most promising solution Cooling test system is in the design phase Blow system experience will be used to build a closed system 13Immanuel Gfall (HEPHY Vienna)10 September 2010

Belle II SVD Upgrade, Mechanics and Cooling Backup 14Immanuel Gfall (HEPHY Vienna)10 September 2010

Belle II SVD Upgrade, Mechanics and Cooling SVD 2 15Immanuel Gfall (HEPHY Vienna)10 September 2010 Tracker used by the Belle experiment (decommissioned June 2010) 4 layers with 246 double sided silicon detectors Dimensions: length of longest ladder 460 mm with a diameter 176 mm All layers consist of linear aligned sensors Cooling was applied only to the hybrid boards at the end rings

Belle II SVD Upgrade, Mechanics and Cooling 16Immanuel Gfall (HEPHY Vienna)10 September Immanuel Gfall (HEPHY Vienna) Design Goals Lowest possible material budget Maximum gravitational sag equal or lower than 100µm over a length of 700mm Minimum coefficient of thermal expansion (CTE) Match or compensation of CTE Low moisture susceptibility Radiation hardness up to 10 Mrad Compliant with the Origami concept

Belle II SVD Upgrade, Mechanics and Cooling 17Immanuel Gfall (HEPHY Vienna)10 September 2010 Endring Ladder Link 15 mm wide mount block separates CF ribs Alignment purpose and CTE compensation Mount point for hybrid boards Thermal control through conduction and cooling ribs Two different designs per ladder to optimize for space 17Immanuel Gfall (HEPHY Vienna) Cable ConnectorsPrecision Pins Ladder Fixture Mountblock Hybrid BoardCooling Ribs

Belle II SVD Upgrade, Mechanics and Cooling 18Immanuel Gfall (HEPHY Vienna)10 September 2010 Barrel Layer 6 18Immanuel Gfall (HEPHY Vienna) Each ladder has a tilt angle of 7 degrees along its center axis The intersection axis between tilt plane and horizontal plane in 140 mm distance specifies the rotation axis Layer 6 contains 17 ladders Cooling Loops Rotation Axis Tilt Plane

Belle II SVD Upgrade, Mechanics and Cooling 19Immanuel Gfall (HEPHY Vienna)10 September 2010 Layer Sensors/ Ladder Origamis/ Ladder LaddersLength [mm]Radius [mm]Slant Angle [°] / SVD Assembly

Belle II SVD Upgrade, Mechanics and Cooling Mollier Chart Blow System 20Immanuel Gfall (HEPHY Vienna)10 September 2010 Subcooling Evaporation Enthalpy kJ/kg Total evaporation -20°C: kJ/kg Cooling capability: 700W+ Mass flow: ~ 7 g/s Cooling Enthalpy: 100kJ/kg Subcooling Enthalpy: kJ/kg