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ECFA meeting muon theme3. Novel Gaseous Detectors and Technology R&D. M. Abbrescia (CMS), P . Iengo (ATLAS), D. Pinci ( LHCb ). General considerations.
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ECFA meeting muon theme3 NovelGaseousDetectors and TechnologyR&D M. Abbrescia (CMS), P. Iengo (ATLAS), D. Pinci (LHCb)
Generalconsiderations • All detectors foreseen for post-LS3 with the aim of restore redundancy or increase coverage should stand a rate capability higher then the present • Because installed in high-ηregions • From 1 kHz/cm2 5-10 kHz/cm2 RPC rate capability • In addition we could be willing to improve also: • Time resolution – from o(1 ns) o(100 ps) • Spatial resolution – from o(1 cm) o(1-0.1 mm) • Given requirement on rate capability, choice of the technology will be driven by the physics case: • plus robustness, cost, easiness of construction, etc. • For instance, o(100 ps) would push us toward RPC multigaps solutions
The technology: Gas Electron Multipliers Developedby F. Sauli in 1997 Eachfoil (perforatedwithholes) is a 50 µm kaptonwithcoppercoatedsides (5 µm ) Typicalholedimensions: Diameter 70 µm, pitch 140 µm • Electron multiplicationtakesplacewhentraversing the holes in the kaptonfoils • Manyfoils can be put in cascadetoachieve O(104) multiplicationfactors • Maincharacteristics: • Excellent rate capability: up to 105/cm2 • Gas mixture: Ar/CO2/CF4 – notflammable • Largeareas ~1 m x 2m with industrial processes (costeffective) • Long termoperation in COMPASS, TOTEM and LHCb
Detector performance • Verygoodtimeresolution • Dependingcritically on the gas mixture • Long R&D on gas (and otherissues) • Excellentspatialresolution • Full efficiency at 104overallgain A new VFAT3 baFEelectronicsbeingdevopedtofully profit fromallthesecaracteristics σt=4 ns Gain = 104 σs = 150 µm
The GEM project: GE1/1 After LHC LS1 the |η|< 1.6 endcapregionwillbecoveredwith 4 layersofCSCs and RPCs; the |η|>1.6 region (mostcritical) willhaveCSCsonly! • Restore redundancy in muon system for robust tracking and triggering • Improve L1 and HLT muon momentum resolution to reduce or maintain global muon trigger rate • Ensure ~ 100% trigger efficiency in high PU environment
And beyond…R&D on glass RPC • New “low” resisitivity (1010Ωcm) glassusedfor high rate RPC • RPC rate capabilitydependslinearly on electroderesistivity • Smootherelectrodesurfaces reduces the intrinsicnoise • Improvedelectronicscharacterizedbylowerthresholds and higheramplification • Single and multi-gapconfigurations under study Readout pads (1cm x 1cm) Mylar layer (50μ) PCB interconnect Readout ASIC (Hardroc2, 1.6mm) PCB (1.2mm)+ASICs(1.7 mm) PCB support (polycarbonate) Gas gap(1.2mm) Cathode glass (1.1mm) + resistivecoating Mylar (175μ) Ceramic ball spacer Glass fiber frame (≈1.2mm) • Excellent performance at localizedbeamtests • Rate capability ~ 30 kHz/cm2 (multi-gap) • Timeresolution 20-30 ps
Needs for new technologies • Operationat the HL-LHC willbeverydemanding for the muon detectors • Alreadyafter LS2 the present muon spectrometerneeds an upgrade in the innerwheels • Degradation of the MDT performance in terms of efficiency and resolution • Level1 muon trigger dominated by fakes in the endcap • A number of R&D programmes on high-rategaseous detectors have been carried out • Small-stripThin Gap Chambers (sTGC) • Micromegas (MM) • Small Monitored Drift Tube (sMDT) • Multi-gapResistive Plate Chambers (mRPC) Selected for the ATLAS New Small Wheel • NSW detector requirements • Spatial resolution O(100um) single plane • Time resolution <10ns for BC identification • Angularresolution 1mrad for trigger decision (vertex pointing) • Rate capability > 14kHz/cm2 • High efficiency (>98%) • Goodageing performance • Double trackresolution (d ~few mm)
sTGC • Technologyimprovements: • In large detectors, resistive cathode reduces the operating voltage. • Go from present TGC resistivity (1 MΩ/cm²) to 100 KΩ/cm² and reduce gap between strips to cathode (transparency prop. to RC). • Good performance athigh rate Detector efficiency vs impact angle Position resolution vs impact angle
Micromegas • ATLAS NSW: first large system based on MM • Technologybreakthroug: • Resistivestrips for sparkimmunities • Construction and operationathigh rate of large-area (few m2) detectors possible • Bulk technique replaced by ‘floatingmesh’ configuration • Good spatial resolutionalso for inclinedtracksthanks to uTPCoperation mode Spark protection system Test with neutron flux 106 Hz/cm2 Non-resistive MM Resistive MM Ydrift(5mm) Position resolution vs impact angle ti, xi Yhalf(2.5 mm) uTPCprinciple xhalf
sMDT • 15 mm diameter tubes • Max drift time 185 ns • Occupancyscaleswith max drift time and tube cross section: 6.5% at 3x1034 cm-2s-1 • Gain loss due to space charge effectscales ~r2 • Good spatial resolutionindipendent on track incidence angle • Standard Al tubes, construction procedureswellunder control to equip large area Efficiency vs counting rate Spaceresolution vs distance from the wire 2350kHz/tube 1100kHz/tube
LHCb (tobeadded)
R&Dneeded (tobeadded)
Conclusions (tobeadded)