Talk #3: Novel Detector technologies and R&D M. Abbrescia, P. - - PowerPoint PPT Presentation

Talk #3: Novel Detector technologies and R&D

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

Preliminary caveat

One 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?)

• ther possible detectors

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

Another caveat

Has cost to be discussed? It was specifically requested in the guidelines There 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 regions From 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.

RPC rate capability

Detectors proposed

Gas Electron Multipliers (GEMs)

Principles of operation

GEMs are made of a copper-kapton-copper sandwich, with holes etched into it

Electron microscope photograph of a GEM foil 8

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: performance

Timing studies

σt=4 ns

GEMs for CMS: performance

Position resolution (full size prototypes)

GEMs for CMS: performance

Efficiency 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: GE1/1

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

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 16

ROC ion feedback (lint and lreadout dependent)

inter. L1a

• Int. + 100ms

t0 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

17

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 pions Relative dE/dx measurements for different HV settings for e and p With momentum from 1 to 3 Gev/c. 46 pad rows used for this analysis 18

fib ⇠ µ fixe field firs fi ⇥

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 community Investigate world-wide needs of different scientific communities in the MPGD technology Optimize 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 projects Applications 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 ATLAS

Another 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 resistivity

CMS/RPCs are characterized by a resistivity around 1010Ωcm

• Proposed 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?) materials Detector 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 interconnect Readout pads (1cm x 1cm) Mylar (175μ) Glass fiber frame (≈1.2mm) Cathode glass (1.1mm) + resistive coating Ceramic ball spacer Gas gap(1.2mm)

New “low” resisitivity (1010 Ωcm) glass used for high rate RPC RPC rate capability depends linearly on electrode resistivity Smoother electrode surfaces  reduces the intrinsic noise Improved electronics characterized by lower thresholds and higher amplification Single and multi-gap configurations under study

New Glass Resistive Plate Chambers

Single gap option Multigap option

GRPCs for CMS

Effect of reduced resistivity on rate capability

Comparison between standard low resistivity (1010 Ωcm) and float glass RPC Caveat: localized irradiation different from an uniform irradiation At 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 rate Rate 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 II High rate, high flux of neutron and photons For 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 facility

GIF++ is being developed at CERN as…

Conclusions

• The 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 pursued Choice (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 example

• Experiences like RD51 should be repeated

BACK-UP SLIDES

Detector performance

Very good time resolution

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

Excellent spatial resolution Full 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 foils

• Many 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