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Concepts and Status of the GEM trackers

Concepts and Status of the GEM trackers. Evaristo Cisbani / INFN-Rome Sanità Group. SBS - Review JLab : 22/Jan/2010. Outline. Requirements for tracking Conceptual design GEM technology Modular approach GEM design details Mechanics Service components Electronics Beam tests

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Concepts and Status of the GEM trackers

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  1. Concepts and Statusof the GEM trackers Evaristo Cisbani / INFN-Rome Sanità Group SBS - Review JLab : 22/Jan/2010 E. Cisbani / SBS Trackers

  2. Outline • Requirements for tracking • Conceptual design • GEM technology • Modular approach • GEM design details • Mechanics • Service components • Electronics • Beam tests • Very preliminary results 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 • Hit rate not an issue Ar/CO2/CF4 (60/20/20) E. Cisbani / SBS Trackers Triple GEM Poli Lener, PhD Thesis - Rome 2005

  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 (Pentchev talk) 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 design based on our preliminary drawing In production

  13. ± 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

  14. 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

  15. 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)

  16. 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

  17. 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

  18. 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

  19. 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

  20. Front End Card 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 Digital IN/OUT + LV ANALOG OUT E. Cisbani / SBS Trackers to the next card First front-end prototypes under test

  21. 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 Prototype Design completed More on DAQ  Hansen Talk

  22. 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: Expected next test/data taking in high lumi at JLab/PREX experiment (with new electronics) • Late Spring/10: Planned test of 40x50 cm2 module at DESY • Demonstrate the large module works as expected • Improve design E. Cisbani / SBS Trackers

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

  24. 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

  25. 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)

  26. 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

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

  28. Conclusions • 3 different trackers required in the SBS experiments; • support high rate, • down to ~70 mm spatial resolution • large areas • 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 • Detail design almost completed, first 40x50 cm2 module in production, test in late Spring/10 • Electronics based on APV25; first prototypes under test E. Cisbani / SBS Trackers

  29. Backup slides E. Cisbani / SBS Trackers

  30. 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

  31. 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

  32. 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

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

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