The CALICE scintillator tile HCAL project Felix Sefkow LCWS’06, Bangalore March 9-13, 2006

Felix Sefkow LCWS06 BangaloreCALICE scintillatoir HCAL project 2 Plan:  Testbeam: proof of principle  HCAL testbeam prototype  Status of preparations  R&D towards a realistic HCAL  Detector concept  R&D around new photo-sensors

Felix Sefkow LCWS06 BangaloreCALICE scintillatoir HCAL project 3 Imaging calorimetry Particle Flow Approach: Reconstruct each particle individually HCAL: separate charged from neutral hadrons –Measure charged particles in the track detector and remove dominant part of hadronic energy fluctuations –Requires high longitudinal and transverse granularity Still need – and get! - very good hadron energy resolution!

Felix Sefkow LCWS06 BangaloreCALICE scintillatoir HCAL project 4 SiPMs for calorimetry Multipixel Geiger Mode APDs –Gain 10 6, bias ~ 50 V, size 1 mm 2 –Insensitive to magnetic fields 3x3 cm scintillator tile with WLS fibre ITEP 1156 pixels with individual quenching resistor on common substrate MEPHI / PULSAR Auto-calibrating but non-linear New era for scintillator– based detectors: High granularity at relatively low cost

Felix Sefkow LCWS06 BangaloreCALICE scintillatoir HCAL project 5 Testbeam “physics” prototype Physics: –Structure of hadron showers –Validation of simulation –Development of particle flow algorithms Technology –gain large scale, long-term experience with a SiPM readout detector –Develop calibration strategy –Identify critical operational issues Running at CERN and FNAL Recently joined

Felix Sefkow LCWS06 BangaloreCALICE scintillatoir HCAL project 6 HCAL testbeam prototype 1 cubic metre 38 layers, 2cm steel plates 8000 tiles with SiPMs Electronics based on CALICE ECAL design, common back-end and DAQ Mechanics and front end boards: DESY Front end ASICs: LAL

Felix Sefkow LCWS06 BangaloreCALICE scintillatoir HCAL project 7 Electronics and calibration Electronics able to resolve single photo-electron signals –Two modes for ~18 bits total dynamic range –Measure MIP light yield in pixels for non-linearity correction –Auto-calibration of SiPM gain, monitor temperature dependence Redundant monitoring system –PIN-stabilized LEDs as reference –Large dynamic range –Temperature sensors 0 pixel 1 pixel 2 pixels

Felix Sefkow LCWS06 BangaloreCALICE scintillatoir HCAL project 8 Prototype commissioning Operational experience already coming in Electronics and calibration functionality being established Develop LCIO-based software See next talk by J. Cvach HCAL module in the DESY testbeam ECAL and HCAL cosmics test Encouraging DAQ: UK groups Calib electr.: Prague Large area trigger in preparation at NIU

Felix Sefkow LCWS06 BangaloreCALICE scintillatoir HCAL project 9 Mechanics Stack support for scintillator and gaseous HCALs built Movable table design for CERN and FNAL being finalized; construction in the next months Only 4 Testbeam set-up includes tail catcher (SiPMs, HCAL electr.) K.Gadow (DESY)

Felix Sefkow LCWS06 BangaloreCALICE scintillatoir HCAL project 10 SiPM mass production Pioneering effort 3 stage selection and characterization –Uncut wafer on probe station (MEPHI/PULSAR) –Semi-automatic test benches for SiPMs and assembled tiles (ITEP) –Being refined after first commissioning experience, linked to performance in assembled detector –Stability tests: 48 elevated bias Have ~ 3000 SiPMs with “data sheets” Expect ~ 2000 more from already produced wafers –Pilot samples being cut for ITEP tests New batch started, expect ready in April

Felix Sefkow LCWS06 BangaloreCALICE scintillatoir HCAL project 11 Prototype construction Mechanical components for active layers ready Electronics and DAQ ready Calibration electronics prototype under test (tight…) 6 modules assembled; tiles for 4 more modules at DESY Production chain set up … –SiPM selection (MEPHI, PULSAR) –SiPM characterization and tile assembly (ITEP) – module assembly (DESY) … for one module per week Cubic metre –half complete in summer –~ fully instrumented for combined run in fall: possible Good news these days

Felix Sefkow LCWS06 BangaloreCALICE scintillatoir HCAL project 12 Preliminary testbeam schedule Draft schedule for CERN North Area beamline H6 –Electrons & hadrons – GeV Parasitic muon running –Co-users mostly upstream ~ 6 weeks total

Felix Sefkow LCWS06 BangaloreCALICE scintillatoir HCAL project 13 Limitations  The design of the testbeam prototype is not realistic: not scalable to a full detector  Front end components not integrated  Electronics not optimized to SiPM signal  Calibration system too complicated  Scintillator layer thickness not minimized  Assembly still quite labour-consuming  A proof-of-principle is possible, but not a realistic performance optimization  A precedence for the electro-mechanical concept of a scintillator calorimeter with integrated photo-sensors does not exist  These issues need to be addressed regardless of final granularity

Felix Sefkow LCWS06 BangaloreCALICE scintillatoir HCAL project 14 Readout configuration The tile HCAL architecture was previously based on readout with clear fibres to photodetectors (e.g. APDs) to be placed outside the detector volume With SiPMs other configurations become possible – one example: following the ECAL architecture –With highly integrated electronics and early data reduction Slab FE FPGA PHY VFE ASIC Da ta Clock+Config+ Control VFE ASIC VFE ASIC VFE ASIC Conf/ Clock

Felix Sefkow LCWS06 BangaloreCALICE scintillatoir HCAL project 15 Mechanical structure The TESLA HCAL had long barrel modules This architecture has been critically revised for SiPMs And confirmed: optimal for minimal cracks / dead material and easy access 1/16 of ½ barrel

Felix Sefkow LCWS06 BangaloreCALICE scintillatoir HCAL project 16 HCAL architecture Typical layer 2m tiles 38 layers tiles FEE: 32 ASICs (LAL) (64-fold) 4 readout lines / layer Layer data Concentrator (control, clock and read FEE) Module data concentrator Instrument one tower (e.m. shower size) + 1 layer (few 1000 tiles) To DAQ EUDET: Mechanical structure, electronics integration: DESY and Hamburg U

Felix Sefkow LCWS06 BangaloreCALICE scintillatoir HCAL project 17 Front end developments New analogue concept –fast auto-trigger –Faster shaping for SiPM amplitude readout –Time measurement –Can work with existing DAQ Future versions –integrate the ADC –more channels Alternative: FADC-like (JINR) Semi-digital option (NIU) C. De La Taille, L.Raux (LAL)

Felix Sefkow LCWS06 BangaloreCALICE scintillatoir HCAL project 18 Calibration system The testbeam system has belts and suspenders –Redundant system, low and high intensity, PIN diodes Operational experience will tell us how to simplify –Really need high intensity? PIN diode? Every tile? We think that we need at least a simple light injection system for debugging and timing checks –Possibly in conjunction with radioactive sources The final readout electronics design depends on calibration procedure –Eg power pulsing may exclude cosmics –Radioactive sources require auto-triggering electronics –Single photo-electron discrimination puts highest demands

Felix Sefkow LCWS06 BangaloreCALICE scintillatoir HCAL project 19 SiPM development Very active field, driven by non-HEP applications –Medical imaging (PET), diagnostics, night vision, radiation monitoring More players entering: –MEPHI/PULSAR, CPTA, JINR, MPI-Munich, Hamamatsu, SensL,… Directions: higher signal – lower noise -cost –Lower noise and / or inter-pixel Xtalk  lower thresholds –Better spectral sensitivity – to blue scintillation light –Larger area and / or better geometrical packing factor Will allow to –Significantly simplify the coupling between SiPM and scintillator Eliminate fibre, ease precision requirements –Or: Use thinner scintillator Save coil cost Buy containment Improve electromagn. Performance  maybe keep the fibre… MEPHI

Felix Sefkow LCWS06 BangaloreCALICE scintillatoir HCAL project 20 Direct coupling Couple to tile without WLS fibre Uniformity worse than with fibre, to be re-addressed Noise too high for single ph.e.e resolution –Alpha source calibration proposed ( 238 Pu) But large dynamic range –up to pixels Simplest coupling possible

Felix Sefkow LCWS06 BangaloreCALICE scintillatoir HCAL project 21 Summary  The goal is to propose a realistic HCAL for the ILC by the end of the decade  Realistic = scalable + basis for costing  Novel technologies  novel concepts: embedded SiPMs and electronics  Two streams of R&D  Towards a realistic detector structure  Connecting to the dynamic photo-sensor developments  Feedback from the testbeam effort will be vital for the refinement of concepts in the near term R&D phase