Novel Gaseous Detectors and Technology R&D

M. Abbrescia (CMS), P. Iengo (ATLAS), D. Pinci (LHCb)

ECFA meeting muon theme3

Marcello Abbrescia EPS, Stockholm 19-Jul-2013- p. 2

General considerations

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-η regionsFrom 1 kHz/cm2 5-10 kHz/cm2

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

RPC rate capability

CMS

Marcello Abbrescia EPS, Stockholm 19-Jul-2013- p. 4

The technology: Gas Electron Multipliers

Electron multiplication takes place when traversing the holes in the kapton foilsMany foils can be put in cascade to achieve O(104) multiplication factors

Main characteristics: Excellent rate capability: up to 105/cm2

Gas mixture: Ar/CO2/CF4 – not flammable Large areas ~1 m x 2m with industrial processes (cost effective) Long term operation in COMPASS, TOTEM and LHCb

Developed by F. Sauli in 1997

Each foil (perforated with holes) is a 50 µm kapton with copper coated sides (5 µm ) Typical hole dimensions: Diameter 70 µm, pitch 140 µm

Marcello Abbrescia EPS, Stockholm 19-Jul-2013- p. 5

Detector performanceVery good time resolution

Depending critically on the gas mixtureLong R&D on gas (and other issues)

Excellent spatial resolutionFull efficiency at 104 overall gain

σt=4 ns

σs = 150 µm

A new VFAT3 baFE electronics being devoped to fully profit from all these caracteristics

Gain = 104

Marcello Abbrescia EPS, Stockholm 19-Jul-2013- p. 6

The GEM project: GE1/1

After LHC LS1 the |η|< 1.6 endcap region will be covered with 4 layers of CSCs and RPCs; the |η|>1.6 region (most critical) will have CSCs only!

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

Marcello Abbrescia EPS, Stockholm 19-Jul-2013- p. 7

And beyond… R&D on glass RPC

PCB support (polycarbonate)PCB (1.2mm)+ASICs(1.7 mm)

Mylar layer (50μ)

Readout ASIC(Hardroc2, 1.6mm)

PCB interconnectReadout pads(1cm x 1cm)

Mylar (175μ)Glass fiber frame (≈1.2mm)

Cathode glass (1.1mm)+ resistive coatingCeramic ball spacer

Gas gap(1.2mm)

New “low” resisitivity (1010 Ωcm) glass used for high rate RPCRPC rate capability depends linearly on electrode resistivitySmoother electrode surfaces reduces the intrinsic noiseImproved electronics characterized by lower thresholds and higher amplificationSingle and multi-gap configurations under study

Excellent performance at localized beam testsRate capability ~ 30 kHz/cm2 (multi-gap)Time resolution 20-30 ps

Needs for new technologies• Operation at the HL-LHC will be very demanding for the muon detectors• Already after LS2 the present muon spectrometer needs an upgrade in the inner

wheels – 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-rate gaseous detectors have been carried out– Small-strip Thin Gap Chambers (sTGC)– Micromegas (MM)– Small Monitored Drift Tube (sMDT)– Multi-gap Resistive Plate Chambers (mRPC)

• NSW detector requirements• Spatial resolution O(100um) single plane• Time resolution <10ns for BC identification• Angular resolution 1mrad for trigger decision

(vertex pointing)• Rate capability > 14kHz/cm2• High efficiency (>98%)• Good ageing performance• Double track resolution (d ~few mm)

Selected for the ATLAS New Small Wheel

ATLAS

sTGC

• Technology improvements:– 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 at high rate Detector efficiency vs impact angle Position resolution vs impact angle

Micromegas

Spark protection system

Yhalf

(2.5 mm)

xhalf

Ydrift

(5mm)

ti, xi

• ATLAS NSW: first large system based on MM• Technology breakthroug:

– Resistive strips for spark immunities– Construction and operation at high rate of large-area (few m2) detectors possible– Bulk technique replaced by ‘floating mesh’ configuration– Good spatial resolution also for inclined tracks thanks to uTPC operation mode

Non-resistive MM Resistive MMTest with neutron flux 106 Hz/cm2

uTPC principle

Position resolution vs impact angle

sMDT• 15 mm diameter tubes

– Max drift time 185 ns– Occupancy scales with max drift time and tube cross section:

6.5% at 3x1034 cm-2s-1

– Gain loss due to space charge effect scales ~r2

– Good spatial resolution indipendent on track incidence angle– Standard Al tubes, construction procedures well under control

to equip large area

Space resolution vs distance from the wire

Efficiency vs counting rate

1100kHz/tube

2350kHz/tube

LHCb(to be added)

R&D needed(to be added)

Conclusions

(to be added)