Talk #3: Novel Detector technologies and R&D

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

Preliminary caveatOne of the main goals of the HL-LHC ECFA workshop is to find synergies between different LHC experiments, and possible follow-ups in terms of common R&D, etc.Therefore the approach of this talk will not be

“experiment-oriented”:novel detectors in CMS novel detectors in ATLAS…. then ALICE, then LHCb

but “detector-oriented”: GEMs in CMS (ATLAS), ALICE and LHCb iRPC in CMS, ATLAS MicroMegas and Thin-Gap in ATLAS (others?)other possible detectors

Here just the (preliminary) material coming from CMS is reportedNote: a dedicated GMM is foreseen on the 23 to look at the full talks

Another caveatHas cost to be discussed?It was specifically requested in the guidelinesThere was some discussion during last meeting with the workshop Steering Committee They requested to include it in the final document (post

ECFA workshop)The general feeling is that:

“it is difficult to discuss of this topic in the restricted framework (and time) of the workshop”“there are too many variables (and options) to be taken into consideration”

During last GMM it was stated that “cost will not be discussed during the

workshop”Decision?

Slides…

Why we need “new” detectors during Phase II?

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 capabilitychoice of the technology will be driven by the physics case:

plus robustness, cost, easiness of construction, etc.

RPC rate capability

Detectors proposed

Gas Electron Multipliers(GEMs)

Principles of operationGEMs are made of a copper-kapton-coppersandwich, with holes etched into it

Electron microscope photograph of a GEM foil

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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 Long term operation in COMPASS, TOTEM and LHCb

Developed by F. Sauli in 1997

Triple-GEM

GEMs for CMS: performanceTiming studies

σt=4 ns

GEMs for CMS: performancePosition resolution (full size prototypes)

GEMs for CMS: performanceEfficiency vs. gain

Gain = 104

Triple GEM detectors, as proposed for the CMS experiment, with different gas mixtures and different gap sizes, in dedicated test-beams – comparison between double and single mask tecniques

Common: single side etching tecnique

Common: the New Stretching Technique

The GEM project: GE1/1After 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

The GEM project for CMS: GE1/1

GEMs for the ALICE TPC

Material provided by the ALICE collaboration

Replace wire chambers With quadruple-GEM chambers

ALICE TPC Upgrade with GEMs

Exploded view of a GEM IROC

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ROC ion feedback (lint and lreadout dependent)

inter. L1a

Int. + 100mst0 t0+7.7ms

GG closed (ion coll. time in ROCs)

Int. + 280ms

GG open (drift time)

Space charge (no ion feedback from triggering interaction)

• GG open [t0, t0+100us], t0 interaction that triggers TPC

• GG closed [t0+100us, t0+280us]

• Effective dead time ~ 280us max readout rate ~3.5 kHz

• Maximum distortions for lint =50kHz and L1=3.5kHz: Dr ~1.2mm (STAR TPC distorsions ~1cm)

Space charge for continuous readout (GG always open)• gain ~6x103

• 20% ion feedback if GG always open ion feedback ~103 x ions generated in drift volume

• Max distortions for 50kHz ~100cm

TPC upgrade – Why?

MWPC not compatible with 50 kHZ operation

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TPC upgrade − GEM-IROC prototype at test-beam

CERN PS TESTBEAM

GEM-IROC only tracks dE/dx: ~10%same as in current TPC

dE/dx spectrum of 1GeV/c electrons and pionsRelative dE/dx measurements for different HV settings for e and pWith momentum from 1 to 3 Gev/c. 46 pad rows used for this analysis 18

GEMs for LHCb

Material to be given by the LHCb collaboration (1-2 slides)

A perfect example of cross-fertilization: RD51 collaboration

RD51 MPGD Collaboration~450 Authors from 75 Institutes from 25 Countries

MicroMegas GEM THGEM MHSP MicroPIC Ingrid

Motivation and Objectives World-wide coordination of the research in the field to advance technological development of Micropattern Gas Detectors.Foster collaboration between different R&D groups; optimize communication and sharing of knowledge/experience/results concerning MPGD technology within and beyond the particle physics communityInvestigate world-wide needs of different scientific communities in the MPGD technologyOptimize finances by creation of common projects (e.g. technology and electronics development) and common infrastructure (e.g. test beam and radiation hardness facilities, detectors and electronics production facilities)The RD51 collaboration will steer ongoing R&D activities but will not direct the effort and direction of individual R&D projectsApplications area will benefit from the technological developments developed by the collaborative effort; however the responsibility for the completion of the application projects lies with the institutes themselves.

http://rd51-public.web.cern.ch/rd51-public/Welcome.html

Micro Megas for ATLASAnother detector studied in the framework of the RD51 collaboration…

(Material to be added)

New Thin Gap Chambers for ATLAS

(Material to be added)

improved Resistive Plate Chambers(iRPC)

Possible options

Rate capability in RPCs can be improved in many ways:Reducing the electrode resistivity (to be < 1010Ωcm)

reduces the electrode recovery time constant τ ≈ ρε– needs important R&D on electrodes materials

Changing the operating conditions reduces the charge/avalanche, i.e. transfers part of the needed amplification from

gas to FE electronics (already done in 1990s!)– needs an improved detector shielding against electronic noise

Changing detector configuration Improves the ratio (induced signal)/(charge in the gap)

Just some of these possibilities are being explored in present R&D

The role of resistivityCMS/RPCs are characterized by a resistivity around 1010ΩcmProposed glass-RPC have a resistivity of the same order of magnitude

At a first approximation, the improvement observed is not due to the resistivity (confirmed by a few hints)

Previous studies and a (semi) theoretical consideration limit the lowest resistivity usable at 107Ωcm

At this point the detector practically looses its self-quenching capabilities (behaves like having metallic plates)

In principle a lot of room (3 orders of magnitude) to exploit:Need studies on (new?) materialsDetector less stable

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

New Glass Resistive Plate Chambers

Single gap optionMultigap option

GRPCs for CMSEffect of reduced resistivity on rate capability

Comparison between standard low resistivity (1010 Ωcm) and float glass RPCCaveat: localized irradiation different from an uniform irradiationAt the moment low resistivity GRPCs at GIF for a series of high rate and aging tests

GRPCs for CMS: performance

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

Multigap performance

Performance at “low” rate

iRPC for ATLAS

R&D@GIF++Essential is to testing these detectors in (harsh) conditions as close

as possible to the ones there will be at LHC phase IIHigh rate, high flux of neutron and photonsFor a long time!

(not all effects are just related to the integrated dose…)Prodution of chemical potentially capable of material damage to be monitored

The environment needed is similar for all detectors

A common facilityGIF++ is being developed at CERN as…

ConclusionsThe novel detectors proposed provide a full range of improved characteristics that fit quite nicely with the ones required for the LHC experiment during phase II

Many different scenarios can be pursuedChoice (when necessary) will be an exciting (and difficult) task!

Detector R&D takes extreme profit from cross-fertilization among different experiments

GEMs in the RD51 framework is the perfect exampleExperiences like RD51 should be repeated

BACK-UP SLIDES

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

Principles of operation (1-2 slides)

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