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Design and Status of the SBS Front tracker

Design and Status of the SBS Front tracker. Evaristo Cisbani / INFN-Rome Sanità Group (largely based on the SBS Review Meeting). SBS Meeting JLab : 19/March/2010. Outline. Requirements for tracking Conceptual design GEM technology Modular approach GEM design details Mechanics

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Design and Status of the SBS Front tracker

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  1. Design and Statusof the SBS Front tracker Evaristo Cisbani / INFN-Rome Sanità Group (largely based on the SBS Review Meeting) SBS Meeting JLab : 19/March/2010 E. Cisbani / SBS Trackers

  2. Outline • Requirements for tracking • Conceptual design • GEM technology • Modular approach • GEM design details • Mechanics • Service components • Electronics • MC • Beam tests E. Cisbani / SBS Trackers

  3. Different (e,e’h) experimental configurations E. Cisbani / SBS Trackers Most demanding High Rates Large Area Down to ~ 70 mm spatial resolution Maximum reusability: same trackers in different setups

  4. Choice of the technology E. Cisbani / SBS Trackers … and modular: reuse in different geometrical configuration GEM mMs Flexibility in readout geometry and lower spark rate

  5. GEM foil: 50 mm Kapton + few mm copper on both sides with 70 mm holes, 140 mm pitch Ionization Multiplication Multiplication Multiplication Readout Strong electrostatic field in the GEM holes GEM working principle E. Cisbani / SBS Trackers Recent technology: F. Sauli, Nucl. Instrum. Methods A386(1997)531 Readout independent from ionization and multiplication stages

  6. Rate capability Ar/CO2/CF4 (60/20/20) E. Cisbani / SBS Trackers Triple GEM Poli Lener, PhD Thesis - Rome 2005  Hit rate not an issue

  7. Aging in COMPASS and LHCb Altunbas et al. NIMA 515 (2003) 249 X-ray 8.9 keV Ar/CO2 (70/30) Use of not-outgassing epoxy Change in HV 25 kHz/mm2 6.3 kHz/mm2 E. Cisbani / SBS Trackers g-ray 1.25 MeV Ar/CO2/CF4 (45/15/40) Expected max. collected charge in GEp: 0.5 mC/mm2/y No significant aging expected Alfonsi et al. Nucl. Phys. B 150 (2006) 159

  8. Spatial Resolution in COMPASS: 70 mm COMPASS readout plane (33x33 cm2) and results (analog readout) E. Cisbani / SBS Trackers C. Altunbas et al. NIMA 490 (2002) 177 70 mm resolution achieved by strips centroid  Analog readout required

  9. Approach: 40x50 cm2 Module Use the same “basic” module for all trackers types • Size: 40x50 cm2 active area + 8 mm frame width • FEM study: • 3 x GEM foils (double mask technology) • 2D strip readout (a la COMPASS) - 0.4 mm pitch • x/y and u/v coordinates E. Cisbani / SBS Trackers • Two exceptions in readout foil: • Front Tracker last 2 chambers: • Double segmented readout to reduce occupancy (Pentchev talk) • Coordinate Detector: • 1D strip readout • 1 mm pitch

  10. Material Budget • Based on the COMPASS GEM • single honeycomb • smaller copper thickness E. Cisbani / SBS Trackers Minimise material to reduce background and multiple scattering

  11. Single Module Mechanical Structure • 3D di Francesco cover drift 3 x transfer+induction honeycomb gas in/out-let detail Service frame E. Cisbani / SBS Trackers

  12. Readout Plane and ZIF extension • Readout along all sides • not strictly required in x/y unless additional segmentation of the readout plane • weight balance • unavoidable in diagonal u/v • Extension feeds into ZIF connectors: • no soldering on the readout foil • permit safer bending • Small frame width (8 mm); minimize dead area • Require precise cutting around the ZIF terminals x/y E. Cisbani / SBS Trackers Rui De Oliveira final design based on our drawing In production

  13. GEM active area SMD resistor pads Detail of the HV distribution • 7 independent HV channels for each chamber (TBC) • 3 HV identical doublets + 1 for drift (same on all GEM foils); each doublet serves one GEM foil, unused will be cut. • SMD protection resistors, under the thin frame 20 5×20 cm2 HV sectors E. Cisbani / SBS Trackers Use the HV modules developed by Corradi/Murtas at LNF

  14. Front Tracker Geometry X(4+4) Back Trackers Geometry SBS Tracker Chambers configuration GEp(5) SBS x6 • Modules are composed to form larger chambers with different sizes • Electronics along the borders and behind the frame (at 90°) – cyan and blue in drawing • Aluminum support frame around the chamber (cyan in drawing); dedicated to each chamber configuration E. Cisbani / SBS Trackers

  15. GEM Trackers Accounting E. Cisbani / SBS Trackers Total chs. 101700 Last 2 FT modules with strips split in the middle (double segmentation on each site) ST and TT readout groups 4 strips in GEp(5) with binary readout

  16. Electronics layout and outer support Green = FE card Cyan = Module frames Cards and modules are supported by an outer aluminum frame which runs all around the chamber. Optimization is in progress. E. Cisbani / SBS Trackers Red= Outer Support Frame

  17. 2D Readout Electronics Components GEMFECADC+VME Controller DAQ 8 mm Up to 10m 49.5 mm 80 mm E. Cisbani / SBS Trackers • Main features: • Use analog readout APV25 chips (wire-bonded on standard PCB, no ceramics): proven to work in COMPASS • ZIF connector on the GEM side (no soldering on readout foil) • Minimum electronics components (front-end + VME custom module) • Copper connection between front-end and VME Thanks to Michael Böhmer and Igor Konorov from TUM for very productive discussions on the design of the APV25 based FrontEnd card

  18. Front-end prototypes tests • Front-end card under control • First tests on analog cable length positive 7 m cable E. Cisbani / SBS Trackers Work is in progress(see date on screenshot) 50 cm cable 50 cm cable Paolo Musico/GE

  19. Beam Tests • Dec/09: preliminary beam test at DESY-II test area (low intensity electron beam from 1 to 6 GeV) of 2 10x10 cm2 2D prototypes + Gassiplex electronics • Characterize the small chamber • Prepare for the full size module test • March/10: GEM under installation in PREX experiment (with Gassiplex electronics, switch to APV25 in May ?) • Early Summer/10: Planned test of 40x50 cm2 module at DESY • Demonstrate the large module works as expected • Improve design • Test APV25 electronics E. Cisbani / SBS Trackers

  20. DESY beam test in Dec/09: setup 2x 10x10 cm2 GEM prototypes Silicon Tracker + scintillator fingers Beam E. Cisbani / SBS Trackers HV Power Supply

  21. DESY beam test in Dec/09 - pedestals Baseline subtracted pedestals Preliminary! E. Cisbani / SBS Trackers Gassiplex Readout (not optimized for negative charge), 700 ns shaping time

  22. DESY beam test in Dec/09 - event example Ar/CO2 70%/30% 3 GeV Electron Beam DGEM = 410 V Vdrift = 2.5 kV/cm VGEM = 2.5 kV/cm Vind = 3.5 kV/cm Preliminary! Single Event E. Cisbani / SBS Trackers Cumulated (Beam profile)

  23. DESY beam test in Dec/09 – x/y correlation DGEM = 410 V Vdrift = 2.5 kV/cm VGEM = 2.5 kV/cm Vind = 3.5 kV/cm Maximum charge in strip E. Cisbani / SBS Trackers Total Charge in cluster

  24. PREX Installation E. Cisbani / SBS Trackers

  25. MonteCarlo/Geant4 • Current model includes: • SiD • Magnet (simple dipole model) • Drift Chamber (for testing) • GEMs (with some sort of electronics) • Working on: • bug fixing, standardize output • general improvement • digitization E. Cisbani / SBS Trackers

  26. SBS Front Tracker Project E. Cisbani / SBS Trackers INFN groups involved in the front tracker development + electronics BA/LE: Gas system + HV CA: Mechanics + Test + MC + Slow Control GE: Electronics ISS/RM: Prototyping, Test, Digitization + Reconstruction, SiD, Coordination Collaboration and funding  Liyanage Talk

  27. Conclusions • GEM technology adopted • high rate and spatial resolution proven in real experiments • Modular approach to get large area detectors, and at the same time to guarantee the already achieved performance • Work in progress: • Production of the first 40x50 cm2 modules • Finalize design of the mechanics • Test Electronics prototypes • Improve MonteCarlo and Digitization and analyze data • Lab/Beam tests of GEM prototype • Setup Infrastructure and tools (clean room, stretcher, quality checls protocol …) E. Cisbani / SBS Trackers

  28. Backup slides E. Cisbani / SBS Trackers

  29. Front End Card Digital IN/OUT + LV Front End card based on COMPASS original design The APV25 chip (originally developed for SiD in CMS) Bus like digital lines (CLOCK, trigger and I2C) & Low Voltages Single differential line for the ANALOG out ZIF connectors on the GEM side (no soldering on readout foil); minimize thickness 800 front-end cards needed ANALOG OUT E. Cisbani / SBS Trackers to the next card Analog frame coming out from the card First front-end prototypes under test

  30. From the VXS backplane: • Trigger L1/L2 • Synch • Clock • Busy (OUT) • (duplicated on front panel) VME64x Custom Controller • VME controller hosts the digitization of the analog signals coming from the front-end card. • Handle all control signals required by the front end cards (trigger/clock/I2C) • Compliant to the JLab/12 VME64x VITA 41 (VXS) standard • Designed with the possibility to detach the ADC subcomponent to extend FEC-VME64x distance (expected to be ~7 m) • 50 modules required E. Cisbani / SBS Trackers First 2 prototypes expected next week

  31. Choice of the frame width - FEM Foil stretched with 30 kg weight Electrostatic field of 10x5 kV/cm (1 Pa) Permaglass frame <40 mm distorsion assumed safe E. Cisbani / SBS Trackers

  32. GEM: Prototype 0 and 1 • First 10x10 prototypes under cosmic test • Using 70/30 Ar/CO2 gas mixture • 7 Independent HV levels up to ~ 4000 V E. Cisbani / SBS Trackers Assembling the GEM chambers parts require a careful quality control at several check points and specific tools for gluing, heating, testing, cleaning Final 40x50 cm2 module finalized; GEM foils and readout ordered

  33. Slow Control HV management is not trivial! 7 HV levels must rump up/down coherently Low pass filters E. Cisbani / SBS Trackers

  34. Clean Room Tools and Facilities Visual inspection back-light board E. Cisbani / SBS Trackers HV single foil testing station Assembling the GEM chambers parts require a careful quality control at several check points and specific tools for gluing, heating, testing, cleaning

  35. Assembling tools: GEM foil stretcher Load cells Uniform and controlled stretching of the foil (30 kg on the load cells) Load cells E. Cisbani / SBS Trackers In production Francesco Noto; inspired by Bencivenni @ al. (LNF)

  36. ± 45° u/v readout plane and fan-out configuration Conceptual design u v E. Cisbani / SBS Trackers 1.25% dead area in v plane (in simpler configuration) Detailed design in progress

  37. Digitization • MC gives track and energy lost (E) in drift region • Extract number of primary electron-ion pairs from poissonian with mean=ni=E/W • Each of the above pair originate from points uniformly distributed along the primary track in drift region • Electrons drift toward the readout at speed vd~5-6 cm/us • Electrons spread (diffuse) on the perpendicular direction with distribution defined by sigma_s=sqrt(2Dt) • The total charge collected from each original pair is gaussanian distributed around the mean gain G=8000 (20x3) with sigma = G*f and gaussian spatially distributed with sigma = sqrt(2Dvd/L), L=drift-readout distance, around the projection of the origin into the readout plane E. Cisbani / SBS Trackers

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