Working Group 1 Summary Technological Aspects and Developments of New Detector structures
WG1: Technological Aspects and Developments of New Detector Structures Objective: Detector design optimization, development of new multiplier geometries and techniques.Task 1: Development of large-area Micro-Pattern Gas Detectors (large-area modules, material budget reduction). Task 2: Detector design optimization including fabrication methods and new geometries (Bulk Micromegas, Microbulk Micromegas, single-mask GEM, THGEM, RETGEM, MHSP, charge-dispersive readout, Ingrid). Task 3: Development of radiation-hard and radio-purity detectors. Task 4: Design of portable sealed detectors.
How will we work? Obviously, the work has to start from the Applications. There will be meetings on the various tasks to compare findings, exchange experience from the applications The first step was to ask, end of May 2008: - What is your preferred technology?(GEM, Micromegas, THGEM, RETGEM, MHSP, Cobra, PIMS, Microgroove, microwell, microdots…) - What are your main applications? (calorimetry, TPC, photon detection, medical, imaging,… - What is your timescale (small prototyping, scale 1 prototyping, delivery of detector, …) 38 institutes out of 54 expressed interest in tasks of Working Group 1 28 on Large Area Detectors (task 1) 9 on Design optimization (task 2, strong overlap with WG2) 20 on Radiation hard and high radiopurity (task 3) 3 on sealed detectors (task 4, recently added)
Task 1: Development of large-area Micro-Pattern Gas Detectors (large-area modules, material budget reduction). Bulk Micromegas Read-out board Laminated Photoimageable coverlay Stretched mesh on frame Laminated Photoimageable coverlay Frame Exposure Development + cure
Raw material Single-side copper patterning Chemical polyimide etching Chemical copper reduction Task 1: Development of large-area Micro-Pattern Gas Detectors (large-area modules, material budget reduction). Single mask GEM
Task 1: Development of large-area Micro-Pattern Gas Detectors (large-area modules, material budget reduction). Copper Thick GEM Raw material CNC drilling Small rim if needed Electrodes etching
Development of large-area Micro-Pattern Gas Detectors Bulk Micromegas Single mask GEM RD51 effect: progress is much faster!
Task 1: Development of large-area Micro-Pattern Gas Detectors (large-area modules, material budget reduction). Mechanical milling 0.6 mm tool diameter 0.8mm 0.8mm 0.6mm Mesh Read-out board Spacer pillar (coverlay) 2.4mm dead region
Task 1: Development of large-area Micro-Pattern Gas Detectors (large-area modules, material budget reduction). Rui de Oliveira • Practical limits (raw material roll width : 600 mm => GEM and mM need seams) • Bulk Micromegas: oven size : 1000 x 2000. Laminator: 1200 x … • GEM: 450mmx100m. No firm limitation provided seems are accepted • THGEM: Time (10-20h for 1000x600 even with 4 drills x 2 PCBs This is the point of view of the fabrication. There are also limits from the point of view of the detector operation and robustness: capacitance Segmentation and possibly resistive components might be necessary for large size detectors. Currently R&D for SLHC muon chambers, calorimetry, etc…
Large volume effect Depends on initial investments Price/area THGEM Micromegas GEM Volume
Task 1: Development of large-area Micro-Pattern Gas Detectors (large-area modules, material budget reduction). Joerg Wotschack Very big collaboration to replace some of the ATLAS Muon chambers (230 m2) Arizona, Athens (U, NTU, Demokritos), Brookhaven, CERN, Harvard, Istanbul (Bogaziçi, Doğuş), Naples, Seattle, USTC Hefei, South Carolina, St. Petersburg, Shandong, Thessaloniki,… Needs triggering capabilities as well as 100 m position resolution and high-rate capability (5 kHz/cm2). Micromegas bulk technology considered as candidate. Recent test beams being analysed. 55 m position resolution demonstrated with strip pitch 250 m at 90°. Cosmic test will follow, 50% prototype being built. Need to keep resolution at angles down to 45°.
Task 1: Development of large-area Micro-Pattern Gas Detectors (large-area modules, material budget reduction). Modules in 2 parts because limitation to 457 mm width from raw material. ‘Splicing’ needed Single mask GEM used to avoid alignment difficulties between top and bottom copper foil. Large GEMs for a forward tracker. Serge Duarte Pinto
Task 1: Development of large-area Micro-Pattern Gas Detectors (large-area modules, material budget reduction). Serge Duarte Pinto Large GEMs for a forward tracker. 3mm seam behaves as expected
Task 2: Detector design optimization including fabrication methods and new geometries (Bulk Micromegas, Microbulk Micromegas, single-mask GEM, THGEM, RETGEM, MHSP, charge-dispersive readout, Ingrid). Cylindrical and flexible GEM and Micromegas (Giani Bencivenni, Frascati and Stephan Aune, Saclay) KLOE and CLAS12 cylindrical trackers also need large GEMs or Micromegas. Why not cylindrical? Low material budget, challenges Silicon Half-cylinder vs full cylinder – integrated and sealed drift cathode. Beam tests at CERN and Brookhaven 75° Lorentz angle in 5T for CLAS12 at Edrift =1kV/cm, reduced to 14° with Edrift=10kV/cm, lower drift velocity (tan q = vB/E)
4 CGEM for KLOE tracker - CLEAN ROOM :we had too many shorts in the detector: ≥ 11 shorts (5% area) in 1.2 m2 of GEM foils (to be compared with) 0 shorts in 4.5 m2 of GEM foils for LHCb
First curved bulk (09-2006) • PCB: 100 µm FR4 with 5 µm thick Cu strip • 100 µm amplification gap • Woven Mesh Gantois non stretched bulk with an array of 400 µm pillar every 2 mm • Dimension: 180 mm x 60 mm Picture: bulk curved, 100 mm radius
SUMMARY on THGEM (Amos Breskin) ● In Ar+5%CH4 the maximum achievable gains measured with UV-light (~106) are ~100-fold higher than with 55Fe (~104) ● Probable explanation is the Raether limit ● In Ne and Ne-CH4 (5-23%) mixtures, under gas flushing, the maximum gains with UV and 55Fe are closer (105 - 106) ● Possibleexplanation: 55Fe photoelectron-tracks are longer in Ne and its mixtures lower density of ionization per hole lower max. gain-difference caused by charge-density effects. ● In pure Ne scintillation prevents high gains & “masks” p.e. extraction quencher ● For RICH: optimal would be Ne–based mixtures ● Quencher additives to be optimized – for high gain and efficient p.e. extraction. ● Preliminary results indicate upon ~70% extraction efficiency in Ne/23%CH4 similar to Ar/5%CH4. ●Charge-up: geometry (rim), gain and rate dependent. ● It seems that rimless holes are advantageous, but need to establish detectors’ parameters (eff QE, e-transfer photon detection efficiency) with the right conditions and gas ● Need to compare stability of LARGE-AREA rim/rimless THGEMs with UV photons ● Tests in RICH mode? Who? When? – Trieste ordered 60x60 cm THGEMs. ● 30x30cm THGEM tests: tested end 2008 at WIS ● Expected results in Cryo-THGEMs Gas Photomultipliers/LXe: early 2009.
Task 2: Detector design optimization including fabrication methods and new geometries (Bulk Micromegas, Microbulk Micromegas, single-mask GEM, THGEM, RETGEM, MHSP, charge-dispersive readout, Ingrid). MHSP (Micro Hole and Strip Plate) (Joao Veloso) and mPIC+Micromegas (Atsuhiko Ochi) Drift plane 1cm Drift/detection area (Filled by gas) Support wire 400mm Cathode Anode 100mm Micro Mesh 165mm 70mm 230mm Micro-mesh Micro-pixel chamber : M3PIC
MicroHole & Strip Plate (MHSP) • Operation Principle Gas JFCA Veloso et al., RSI 71(2000)2371
MicroHole & Strip Plate (MHSP) Present Performance: High gains – ~ 104-105 Fast charge collection – 10 ns Excellent energy resolution – 13.5% @ 5.9keV x-rays - Xe High rate capability – > 0.5 MHz/mm2 High pressure operation capability High ion blocking capability 2-D intrinsic capability – σ~125μm (with resistive line)
First demonstration of a GPM operation in visible range 0.03% No visible feedback A. Lyashenko et al., NIMA (2008), http://arxiv.org/abs/0808.1556v2
Carbon dissociated from ethane deposits on polyimide surface 5 sparks 50 sparks 150 sparks 300 sparks 200 sparks 2nd RD51 Paris 14th Octber 2008
Correlation between number of discharges and voltage drop after the test 2nd RD51 Paris 14th Octber 2008
MESHES Many different technologies have been developped for making meshes (Back-buymers, CERN, 3M-Purdue, Gantois, Twente…) Exist in many metals: nickel, copper, stainless steel, Al,… also gold, titanium, nanocristalline copper are possible. Chemically etched Deposited by vaporization Electroformed Wowen Laser etching, Plasma etching… PILLARS 200 mm Can be on the mesh (chemical etching) or on the anode (PCB technique with a photoimageable coverlay). Diameter 40 to 400 microns. Also fishing lines were used (Saclay, Lanzhou)
Detector design optimization, fabrication methods and new geometries 104 6 keV X-ray pitch = 1 mm; diameter = 0.5 mm; rim=40; 60; 80; 100; 120 mm THGEM Example Mask etching + drilling; rim = 0.1mm drilling + chemical rim etching without mask
3÷10 G/ 1 M/ plastic foil mesh resistive foil glue pads PCB Development of resistive anodes and grids Resistive anode: Charge dispersion readout copper oxide layer RTGEM: resistive electrode THGEM
Task 3: Development of radiation-hard and high radio-purity detectors. • A few people interested, will follow up
Task 4: Design of portable sealed detectors • New task (discussion this morning) • Make gas-tight low-outgasing detectors with locally made high-voltage, and portable (USB?) electronics • Possible applications: radiotherapy (positioning), teaching,… • Interested people: Amos Breskin, Paul Colas, Rui de Oliveira, Per Baecklund, Fabrizzio Murtas, Joaquim Dos Santos,… • ==> phone meeting early November.
Interactions of WG1 WG2 WG6 Production Characterization, basic studies on performance, aging New materials, new geometries WG4 Simulations WG1 Protection WG5 Electronics WG7 Test beams