Activity of CERN and LNF Groups on Large Area GEM Detectors 11th Pisa Meeting on Advanced Detectors La Biodola, 26.05.09 Activity of CERN and LNF Groups on Large Area GEM Detectors Danilo Domenici INFN - LNF 11th Pisa Meeting on Advanced Detectors – 26.05.09

LNF and CERN in RD51 Collaboration LNF and CERN groups work together within the RD51 Collaboration: Development of Micro-Pattern Gas Detectors Technologies WG1/Task1: Technological Aspects and Development of New Detector Structures / Large Area GEM Detectors Installed and working detectors: 20 31x31cm2 Triple-GEM in COMPASS NIM A490 (2002), 177 40 14.5cm  Triple-GEM in TOTEM NPPS 172 (2007), 231 24 20x24cm2 Triple-GEM in LHCb NIM A494 (2002), 156 Need for Large-Area GEM Present size limitation: ~450x450mm2 Width of raw material (457mm roll) Alignment precision of double-mask procedure 11th Pisa Meeting on Advanced Detectors – 26.05.09

Standard Double-Mask Procedure Starting raw material: 50μm Kapton foil with 5μm Copper clad Photoresist coating , Double Mask are laid down and exposed Double side metal etching Double side kapton etching. The hole has bi-conical shape 11th Pisa Meeting on Advanced Detectors – 26.05.09

New Single-Mask Procedure Starting raw material: 50μm Kapton foil with 5μm Copper clad Photoresist coating, Single Mask are laid down and exposed Hole is opened with top side metal etching and kapton etching Bottom side metal etching. Top side metal is preserved with Cathodic Protection technique Back to kapton etching for 30 s to get cylindrical shaped hole Eventual quick metal etching to form the rim 11th Pisa Meeting on Advanced Detectors – 26.05.09

Hole Geometry STD GEM NEW GEM 70 50 5um Cu 70 65 5um Cu 11th Pisa Meeting on Advanced Detectors – 26.05.09

Nearly Cylindrical Holes TOP Kapton TOP Sparking voltage 700 V in air BOT Kapton BOT 11th Pisa Meeting on Advanced Detectors – 26.05.09

Single-GEM chamber layout X-Ray Measurements Single-GEM chamber layout 4 mm Drift Gap 2 mm Induction Gap Current readout Single-GEM readout in current mode 2 identical chambers have been tested with X-rays: 1 with single-mask foil 1 with standard foil Flushed on the same gas line and irradiated with front and side openings of the gun GAS: Ar/CO2 70/30 11th Pisa Meeting on Advanced Detectors – 26.05.09

Electron Transparency X-Ray Measurements Electron Transparency 80% at 0 Field: larger Optical Transparency due to larger diameter VGEM = 400V Ed = 1.5kV/cm 11th Pisa Meeting on Advanced Detectors – 26.05.09

X-Ray Measurements Ion Feedback VGEM = 400V Ed = 1.5kV/cm 11th Pisa Meeting on Advanced Detectors – 26.05.09

X-Ray Measurements Charge Sharing Equal Sharing Field highly dependent on New-GEM orientation 4.6kV/cm 5.7kV/cm VGEM = 400V Ed = 1.5kV/cm 5.2kV/cm 11th Pisa Meeting on Advanced Detectors – 26.05.09

X-Ray Measurements Gas Gain G60-70 / Gstd = 0.67 G70-60 / Gstd = 0.80 Additional 10  20 V needed to operate at the same Gain as Standard GEM 11th Pisa Meeting on Advanced Detectors – 26.05.09

Simulation: Drift Lines 95–55 75–55 55–55 55–75 55–95 11th Pisa Meeting on Advanced Detectors – 26.05.09

Simulation: Field Intensity 95–55 75–55 55–55 55–75 55–95 11th Pisa Meeting on Advanced Detectors – 26.05.09

Future Applications CERN TOTEM Upgrade LNF KLOE Upgrade 11th Pisa Meeting on Advanced Detectors – 26.05.09

TOTEM Large Prototype Idea of upgrade for T1 tracker (now Cathode-strips Wire chamber) Discs of 2 x 5 chambers, back to back, allow to cover all the surface Large Triple-GEM prototype (~ 2000 cm2) obtained from two 66x33cm2 foils 11th Pisa Meeting on Advanced Detectors – 26.05.09

Efficiency with X-rays ( 0.5mm collimator) Splicing GEM heat pressure Foils are spliced over a narrow seam using an adhesive flexible kapton coverlayer (25µm thick) Efficiency with X-rays ( 0.5mm collimator) 11th Pisa Meeting on Advanced Detectors – 26.05.09

Manufacturing of Prototype Stretching and framing the spliced single mask gem foils Making the honeycomb base plane and top cover 11th Pisa Meeting on Advanced Detectors – 26.05.09

Manufacturing of Prototype Gluing the cathode to the honeycomb frame Final assembly of all frames 11th Pisa Meeting on Advanced Detectors – 26.05.09

Performance preliminary hole geometry Energy Resolution with 8.9keV X-rays σE/E = 9.5% Rate Capability up to 1MHz/mm2 Voltage Sum (V) Effective Gain Triple-GEM Gain in Ar/CO2 preliminary hole geometry 11th Pisa Meeting on Advanced Detectors – 26.05.09

Cylindrical Triple GEM KLOE2 Inner Tracker 3 mm 2 mm Cathode GEM 1 GEM 2 GEM 3 Anode Read-out Conversion & Drift Transfer 1 Transfer 2 Induction Cylindrical Triple GEM 5 independent tracking layers 15 to 25 cm from IP to improve vertex reconstruction σrφ = 200 µm and σZ = 500 µm spatial resolutions with XV strips-pads readout 700 mm active length 1.5% X0 total radiation length in the active region with Carbon Fiber supports  300 x 352mm prototype with Std GEM has been assembled and tested Realized as an innovative Cylindrical-GEM detector 11th Pisa Meeting on Advanced Detectors – 26.05.09

Manufacturing the Prototype 352 mm 960 mm 2 3 Full sensitive and Ultra-light detector 1 4 5 Distribution of epoxy on foil edge 3 spliced foils ~1000mm long Cylindrical mould in vacuum bag Cylindrical GEM foil Cylindrical Cathode with annular fiberglass support flanges 11th Pisa Meeting on Advanced Detectors – 26.05.09

(GEM) =(250µm)2 – (140µm)2  200µm Performance Efficiency ε = 99.6% Performance measured at PS testbeam with GASTONE digital Readout Electronics (INFN-Bari) and external Drift Tubes Tracking System Spatial Resolution (GEM) =(250µm)2 – (140µm)2  200µm 11th Pisa Meeting on Advanced Detectors – 26.05.09

Large Planar Prototype Cathode PCB 70x30 cm2 Triple-GEM planar detector with Single-mask foils for quality and uniformity test GEM1 GEM2 GEM3 1.5x2.5 cm2 pad readout PCB 11th Pisa Meeting on Advanced Detectors – 26.05.09

Tooling and Simulations Meters With the usual 1 kg/cm, finite element simulation (ANSYS) indicates a maximum gravitational+electrostatic sag of the order of 20 μm Load Cells Jaws A very large tensioning tool has been designed. The frame gluing will be performed by using the “vacuum bag” technique, tested in the construction of the CGEM 11th Pisa Meeting on Advanced Detectors – 26.05.09

RD51 Testbeam Facility WG7: Common Test Facilities H4 beam-line at SPS: 150GeV pions Goliath Magnet: dipole field up to 1.5T in a ~3x3x1m2 Semi-permanent setup for RD51 users First test June 21st – July 6th CERN: Large-GEM prototype LNF: XV readout and BField Beam direction RD51 setup Goliath magnet 11th Pisa Meeting on Advanced Detectors – 26.05.09

Conclusions A change of the GEM production procedure has been driven by the wide request of Large Detectors by the GEM community A new Single-Mask and Cathodic Protection etching technique has been tuned, allowing for foils as large as 450x2000mm2 The short size limitation, due to the definite width of the raw-material, can be overcome by splicing more foils together A Single-Mask 10x10cm2 foil has been tested with X-rays in a Single-GEM detector readout in current mode. Results show slight difference with the standard GEM LNF and CERN groups are developing Large-GEM detectors for future applications: TOTEM upgrade and KLOE upgrade Other possible applications are Super-LHC Detector upgrades (LHCb TT and Muon), Screening for homeland security and PET scanners 11th Pisa Meeting on Advanced Detectors – 26.05.09

SPARES

An example of active corrosion protection Cathodic Protection An example of active corrosion protection CP is a technique to control the corrosion of a metal surface by making it work as a cathode of an electrochemical cell. Used to protect ship hulls and oil pipes 0V +3V +3V Resist layer to protect back part from the bath Bottom electrode at +3V is chemically etched Bath at +3V Top electrode at ground is electrically protected 11th Pisa Meeting on Advanced Detectors – 26.05.09

Single-Mask Etching Isotropic metal etching Resist layer Opening of the hole, but unwanted angles in the copper Over-etching of the copper Going back to Polyimide etching for 30 sec The hole become cylindrical 11th Pisa Meeting on Advanced Detectors – 26.05.09

Helium-Isobuthane 11th Pisa Meeting on Advanced Detectors – 26.05.09

Relative Gain vs GEM Voltage Single-GEM X-Ray Measurements Relative Gain vs GEM Voltage Single-GEM Edrift = 1.5 kV/cm Eind = 5 kV/cm 11th Pisa Meeting on Advanced Detectors – 26.05.09

Normalized gain vs VGEM X-Ray Measurements 40V Normalized gain vs VGEM Triple-GEM Data normalized to previous Absolute gain measurements with Ar/CO2 70/30 Fields: Ed=1.5 – Et1=2.5 – Et2=3.0 – Ei=5.0 11th Pisa Meeting on Advanced Detectors – 26.05.09

2-D Readout Circuits Both views can be readout from the 2 ends of the circuit: suitable for a cylindric geometry without dead spaces 650 µm pitch V strips Orthogonal XY 650 µm pitch X strips 11th Pisa Meeting on Advanced Detectors – 26.05.09

Readout studies: 2-D strips Cluster multiplicity studies on the first two XY chambers Gast1: induction gap 2 mm Gast2: induction gap 1 mm 11th Pisa Meeting on Advanced Detectors – 26.05.09

Simulation of effects of a Magnetic Field (B=0.5T) on a Triple-GEM Readout studies: B-Field Simulation of effects of a Magnetic Field (B=0.5T) on a Triple-GEM Ar/CO2=70/30 <α>L ~ 8o 9o 9mm 1.2mm He/i-C4H10=90/10 <α>L ~ 3o 4o 0.6mm 11th Pisa Meeting on Advanced Detectors – 26.05.09