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CALICE STATUS

CALICE STATUS. Mark Thomson University of Cambridge. For the CALICE-UK groups: Birmingham, Cambridge, Imperial, Manchester, RAL, UCL. Overview UK Hardware UK Simulation UK Reconstruction Conclusions. 62 % charged particles : 27 % g : 10 % K L ,n : 2 % n.

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CALICE STATUS

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  1. CALICE STATUS MarkThomson University of Cambridge For the CALICE-UK groups: Birmingham, Cambridge, Imperial, Manchester, RAL, UCL • Overview • UK Hardware • UK Simulation • UK Reconstruction • Conclusions LCUK Meeting, Oxford

  2. 62 % charged particles : 27 % g : 10 % KL,n : 2 % n Charged particles in tracking chambers Photons in the ECAL Neutral hadrons in the HCAL (and possibly ECAL) Calorimetry at a Future LC • Much LC physics depends on reconstructing invariant masses from jets in hadronic final states • Kinematic fits don’t help – Beamstrahlung, ISR • Jet energy resolution is of vital importance The energy in a jet is: The Energy Flow/Particle Flow Method • Reconstruct momenta of individual particles avoiding double counting • need to separate energy deposits from different particles LCUK Meeting, Oxford

  3. Energy flow drives calorimeter design: • Separation of energy deposits from individual particles • small X0 and RMoliere: compact showers • high lateral granularity : O(RMoliere) KL,n • Discrimination between EM and hadronic showers p • small X0/lhad e g • longitudanal segmentation • Containment of EM showers in ECAL granularity more important than energy resolution, i.e. $$$ Calorimeter Requirements ECAL LCUK Meeting, Oxford

  4. Calorimeter Concept • ECALandHCAL inside coil • Better performance – but impacts cost • ECAL: silicon-tungsten (SiW) calorimeter: • Tungsten : X0 /lhad = 1/25, RMoliere ~ 9mm • (gaps between Tungsten increase effective RMoliere) • Lateral segmentation: 1cm2 matched toRMoliere • Longitudinal segmentation: 40 layers (24X0,0.9lhad) HCAL: digital vs. analogue (major open question): • Tile HCAL (Analogue readout) Steel/Scintillator sandwich Lower lateral segmentation 5x5 cm2(motivated by cost) • Digital HCAL High lateral segmentation 1x1 cm2butdigital readout RPCs, GEMS… LCUK Meeting, Oxford

  5. AIMS • Study calorimetry for a future linear collider • Proposed high-granularity ECAL/HCAL $$$ need to fully justify/optimize the calorimetry for FLC • Testbeam studies of ECAL and HCAL ECAL studies of Si-W calorimeter HCAL studies of both analogue and digital options GOALS: • Demonstrate technical feasibility of ECAL • Validate MC simulation (particularly hadronic showers ) vital for optimisation of final design • Study digitalvs analogueHCAL PEOPLE: • 177 people, 27 institutes (including DESY) • 23 UK collaborators ! CALICE Collaboration LCUK Meeting, Oxford

  6. UK Contribution • Readout and DAQ for test beam prototype Provide readout electronics for the ECAL (Possibly use UK boards for some HCAL options) DAQ for entire system • Simulation studies ECAL cost/performance optimisation Impact of hadronic/electromagnetic interaction modelling on design. Comparisons of Geant4/Geant3/Fluka • Reconstruction/Energy Flow Started work towards ECAL/HCAL reconstruction Ultimate goal – UK Energy flow algorithm • Luminosity spectrum from Bhabha acolinearity (UCL) LCUK Meeting, Oxford

  7. HCAL DAQ ECAL 1m Beam monitor Test Beam and Prototype • Combined ECAL & HCAL • Engineering Run late 2004 in e- beam at DESY (ECAL only) • Physics Run in 2005 p/p+beam at FNAL (TBC) • HCAL: 38 layers Fe • Insert combinations of: • “digital” pads (350k, 1x1cm2 pads) • GEM • RPC • “analogue” tiles (8k, 5x5cm2) • Scintillator tiles Moveable table LCUK Meeting, Oxford

  8. Prototype ECAL • 3x10 layers, Si-W 0.4X0, 0.8X0, 1.2X0 • Each layer 3x3 wafers • Each wafer 6x6 pads 9720 channels total Carbon Fibre/ Tungsten Si/W/Si Sandwich External Readout (VFE) Wafers LCUK Meeting, Oxford

  9. Readout Overview • CALICE ECAL has 9720 channels • Each gives analogue signal, 14-bit dynamic range • Very-front-end (VFE)ASIC (Orsay) multiplexes 18 channels to one output line • VFE-PCB handles up to 12 VFEs (216 channels) • Cables from VFE-PCBs go directly to UK VME readout boards, called Calice ECAL Readout Cards (CERCs) • Based heavily on CMS tracker readout • Rutherford Laboratory • Adam Baird, Rob Halsall, Ed Freeman • Imperial College London • Osman Zorba, Paul Dauncey • University College London • Matt Warren, Martin Postranecky • Manchester University • Dave Mercer LCUK Meeting, Oxford

  10. CERC status • Prototype design completed last summer • Two prototype boards fabricated last year • Arrived on November 21 at Rutherford Laboratory • Currently under stand-alone tests in the UK • Aim to test with a VFE-PCB in the UK very soon • Move UK hardware to Paris (Ecole Polytechnique) for cosmic tests with fully populated VFE-PCB with Si wafers in Feburary Front End FPGAs Back End FPGA LCUK Meeting, Oxford

  11. Outstanding Issues • Final path for data has several complex steps • FE digitises ADC data for each trigger • Automatically transferred to 8MByte memory • Memory read from VME when bandwidth available • Needs data transfer, memory control and VME interface • BE FPGA firmwarenot yet functional • Memory components delayed in delivery; not yet mounted on CERCs • Aiming for end of March for all this to be working ! • Backup for VFE tests • Implement simple RS232 interface from PC to BE and hence to FEs • RS232 reads FIFO one word at a time directly to PC • 8MByte memories bypassed, must read each event before next trigger • Rate is slow ~1Hz for events; sufficient for cosmics LCUK Meeting, Oxford

  12. Schedule • VFE tests in Paris in February Essential test of prototypes before moving to production • Possible AHCAL test in April Need more information on what is required; number of channels, interface specification for VFE-PCB equivalent,… • Finalise redesign by end March • Re-layout/fabricate 9 production CERCs in April-May Simple fixes for the few known problems may be possible If so, maybe no need to re-layout; save a month Only have components for nine boards; need to know early if more wanted for HCAL Will need non-UK funds for HCAL readout • Full ECAL system tests from July onwards • On schedule for DESY ECAL test beam in Oct/Nov LCUK Meeting, Oxford

  13. Test Beam Requirements • What Data ? Proton/pion/muon ? • How much data ? 5 GeV p+ • Use MC studies to study what data would be most useful in validating MC models (David Ward) • e.g. Compare samples of 5 GeV p+ in Geant3 (histo) and Geant4 (points) • Significant differences seen at the level of 104 events • HCAL shows greatest discrepancies LCUK Meeting, Oxford

  14. Differences depend on Energy 1 GeV p+ 50 GeV p+ • Therefore scan over energies LCUK Meeting, Oxford

  15. Protons vs Pions 5 GeV p 5 GeV p+ • Need to understand beam ! i.e. pion/proton ratio • Find protons/neutrons v. similar (at least in MC) • Greater differences for Scintillator HCAL vs. RPC LCUK Meeting, Oxford

  16. Test Beam : Conclusions • 1% precision suggests >104 events per particle type and energy. • Would like energies from 1-80 GeV (~10-15 energy points?). • Pions and protons desirable (Čerenkov needed). +Electrons (+ muons?) for calibration. • Need to understand beam • Both RPC and Scintillator HCAL needed. • Position scan – aim for 106 events/energy point? • Also some data at 30-45o incidence. LCUK Meeting, Oxford

  17. Study of hadronic models (G Mavromanolakis, N. Watson) Compare: (G Mavromanolakis) • Geant 3 with Gheisha • Geant 3 / Gheisha (SLAC version) • Geant 3 / Fluka • Geant 3 / Fluka / Micap(used for n < 20 MeV) • Geant 4 / Mokka Also Studying: • Variations of Geant 3/Geant 4 cutoffs (G Mavromanolakis) • Geant 4 FLUKA(N.Watson) - Geant 3 version deprecated - Geant 4 implementation extremely interesting - tricky to get working, but making excellent progress LCUK Meeting, Oxford

  18. Calorimeter Reconstruction • High granularity calorimeter – very different from previous detectors • `Tracking calorimeter’ • Requires new approach to reconstruction • Already a lot of good work on powerful energy flow algorithms • Still room for new ideas/ approaches • Current codes : inflexible UK Effort just starting (Chris Ainsley) • Important for future analysis and `energy flow’ • studies/detector optimisation LCUK Meeting, Oxford

  19. ECAL Clustering • Aim – to produce a flexible algorithm, not tied to specific geometry/MC program. • Algorithm needs to cope with tracks and clusters • Sum hits within cell; apply threshold of ⅓ MIP • Form clusters in layer 1 of ECAL. • Associate each hit in layer 2 with nearest hit in layer 1 within cone of angle a. If none, initiate new cluster. • Track onwards layer by layer through ECAL and HCAL, looking back up to 2 layers to find nearest neighbour, if any. LCUK Meeting, Oxford

  20. Example Events 15 GeV e- 15 GeV p- Handles CLUSTERS and TRACKS (Reconstructed clusters are colour-coded, black = highest energy cluster) LCUK Meeting, Oxford

  21. Some more difficult examples 15 GeV t- 15 GeV h • Separates nearby ECAL clusters • So far things look good, but this is just the first stage LCUK Meeting, Oxford

  22. Conclusions • CALICE ECAL prototype progressing well - test beam before end of 2004 ! • Confident that UKElectronics/DAQ will be ready • Work on Digitization simulation starting(D.Bowerman, C.Fry) • UK contributing significantly to understanding FNAL test beam requirements • On-going studies of hadronic models • UK reconstruction effort starting - important for analysis of test beam data - important for optimisation of ECAL design • Next 2 years are going to be very interesting • UK groups well placed to participate in analysis of test beam data LCUK Meeting, Oxford

  23. LCUK Meeting, Oxford

  24. RPC vs. Scintillator HCAL RPC Scintillator LCUK Meeting, Oxford

  25. Neutrons vs Protons 5 GeV p 5 GeV n LCUK Meeting, Oxford

  26. CERC overview • Eight Front End (FE)FPGAs control all signals to front end electronics via front panel input connectors • Back End (BE)FPGA gathers and buffers all event data from FE and provides interface to VME • Trigger logic in BE for timing and backplane distribution; only active in one board • Each input is one full or two half-full VFE-PCBs; need 45 inputs = 6 CERCs • Based on CMS tracker readout (FED) LCUK Meeting, Oxford

  27. Readout Details • Based on CMS silicon tracker readout (FED) Will “borrow” a lot of firmware from them Unfortunately not yet as well-developed as hoped • Dual 16-bit ADCs and 16-bit DAC DAC fed back for internal as well as front end calibration ADC 500kHz; takes ~80ms to read and digitise event data from VFE-PCB • No data reduction in readout board ECAL event size: 3.5 kBytes per board, 20 kBytes total per event • On-board buffer memory; 8 MBytes No buffering available in ECAL front end; receive data for every trigger Memory allows up to ~2k event buffer on readout board during beam spill VME readout speed ~20 MBytes/s; several seconds readout after spill • Large amount of unused I/O from BE FPGA to backplane Will implement trigger logic and control/readout interface to VME in BE LCUK Meeting, Oxford

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