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Development of m icromegas for the ATLAS Muon System Upgrade . Jörg Wotschack (CERN) MAMMA Collaboration

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Development of m icromegas for the atlas muon system upgrade

Development of micromegas for the ATLAS Muon System Upgrade

JörgWotschack (CERN)

MAMMA Collaboration

Arizona, Athens (U, NTU, Demokritos), Brandeis, Brookhaven, CERN, Carleton, Istanbul (Bogaziçi, Doğuş), JINR Dubna, MEPHI Moscow, LMU Munich, Naples, CEA Saclay, USTC Hefei, South Carolina, Thessaloniki

Work performed in close collaboration with CERN/TE-MPE PCB workshop (Rui de Oliveira)

Lots of synergy from the RD51 Collaboration


Outline
Outline

  • The ATLAS Muon System upgrade

  • The micromegas technology

  • Making micromegas spark-resistant

  • Performance & ageing studies

  • Two-dimensional readout structure

  • Towards large-area micromegas chambers

  • First data from ATLAS

  • Next steps

Not covered: electronics

Joerg Wotschack (CERN)


The mamma r d activity
The MAMMA*) R&D activity

  • Using the micromegas technology to build muon chambers for the ATLAS upgrade was first suggested in an ATLAS Muon Collaboration brainstorming meeting back in 2007 by I. Giomataris (CEA Saclay)

    • By this time MMs had been successfully used in several experiments at very high rates (COMPASS, NA48) but the largest chambers did not exceed 0.4 x 0.4 m2

    • The idea looked intriguing to some of us

  • Profiting from the know-how of the CERN PCB workshop, the first prototype chamber, 0.4 x 0.5 m2 in size, was built still in 2007; it worked very nicely

  • By 2009 the excellent performance of MMs and their potential for large-area muondetectors was demonstrated

  • 2010 was dedicated to making micromegas spark resistant

  • 2011 the first resistive large-area chambers successfully built and tested

*) Muon ATLAS MicroMegas Activity

Joerg Wotschack (CERN)


The atlas muon system upgrade
The ATLAS Muon System Upgrade

Joerg Wotschack (CERN)


Count rates in the atlas muon system at s 14 tev for l 10 34 cm 2 s 1
Count rates*)in the ATLAS Muon System at √s = 14TeV for L = 1034 cm-2s-1

Small Wheel

Rates in Hz/cm2

Rates at inner rim

1–2 kHz/cm2

*) ATLAS Detector paper, 2008 JINST 3 S08003

Joerg Wotschack (CERN)


The atlas detector
The ATLAS detector

  • Small Wheels

Joerg Wotschack (CERN)


Rates measurement vs simulation
Rates: measurement vs simulation

Measured and expected count rates and in the Small Wheel detectors Data correspond to L = 0.9 x 1033 cm-2s-1 at √s = 7 TeV

Ratio between MDT data and FLUGG*) simulation (CSC region not shown)

Rate in Hz/cm2 as a function of radius in the large sectors

*) FLUGG simulation gives rates about factor 1.5 – 2 higher than old simulation

Joerg Wotschack (CERN)


Three reasons for new small wheels
Three reasons for new Small Wheels

  • Small Wheel muon chambers were designed for a luminosity of L = 1 x 1034 cm-2 s-1

    The rates measured today are 2–3 x higher than estimated;

    all detectors in the SW will be at their rate limit at 5 x 1034cm-2 s-1

  • Eliminate fakes in high-pT(> 20 GeV) triggers

    At higher luminosity pT thresholds of 20-25 GeV are a MUST

    Currently over 95 % of forward high pTtriggers are fake

  • Improve pT resolution to sharpen thresholds

    Needs ≤1 mrad pointing resolution

Joerg Wotschack (CERN)


The problem with the fake tracks
The problem with the fake tracks

  • Current LVL1 end-cap trigger

  • Only the vector BC at the Big Wheels is measured

  • Momentum defined by assumption that track originated at IP

  • Random background tracks can easily fake this

  • Currently 96% of forward high-pTtriggers (at LVL1) have no track associated with them

  • Proposed LVL1 trigger

  • Add vector A at Small Wheel

  • Powerful constraint for real tracks

  • A pointing resolution of 1 mradwill also improve pTresolution

Joerg Wotschack (CERN)


Small wheel p erformance requirements
Small Wheel performance requirements

  • Rate capability 15 kHz/cm2 (L ≈ 5 x 1034 cm-2s-1)

  • Efficiency > 98%

  • Spatial resolution ≈100 m (Θtrack< 30°)

  • Good double track resolution

  • Trigger capability (BCID, time resolution ≤ 5–10 ns)

  • Radiation resistance

  • Good ageing properties

All requirements can be met with micromegas

Joerg Wotschack (CERN)


Atlas small wheel upgrade proposal
ATLAS Small Wheel upgrade proposal*)

Replace the muon chambers of the Small Wheels with 128 micromegas chambers (0.5–2.5 m2)

  • Combine precision and 2ndcoord. measurement as well as trigger functionality in a single device

  • Each chamber comprises eight active layers, arranged in two multilayers

    • a total of about 1200 m2 of detection layers

    • 2M readout channels

Today:

MDT chambers (drift tubes) +

TGCs for 2nd coordinate (not visible)

2.4 m

CSC chambers

  • *) other candidates: combined systems

  • sMDT+TGCand sMDT+RPC

Joerg Wotschack (CERN)


The micromegas technology
The micromegas technology

Joerg Wotschack (CERN)


Micromegas operating principle
Micromegasoperating principle

-800 V

-550 V

Conversion & drift space

(few mm)

Mesh

Amplification

Gap 128 µm

The principle of operation

of a micromegas chamber

  • Micromegas (I. Giomataris et al., NIM A 376 (1996) 29) are parallel-plate chambers where the amplification takes place in a thin gap, separated from the conversion region by a fine metallic mesh

  • The thin amplification gap (short drift times and fast absorption of the positive ions) makes it particularly suited for high-rate applications

Joerg Wotschack (CERN)


Micromegas characteristics
Micromegas characteristics

  • Drift region of a few mm with moderate electric field of 100–1000 V/cm, function of the gas

  • Narrow amplification gap with high electrical field (40–50 kV); typically a factor 70–100 is required to make the mesh fully transparent for electrons

  • Charged particles ionize the gas in the drift region, the electrons move with typically 5 cm/µs (or 20 ns/mm) to and through the mesh and are amplified in the amplification gap

  • By measuring the arrival time of the signals a MM functions like a TPC

Joerg Wotschack (CERN)


An established technology
An established technology

  • Micromegas were (and are) used successfully in the COMPASS experiment as vertex chambers in a high-rate muon beam

    • 12 planes with dimensions 400 x 400 mm2

    • Strip pitch: 360 µm; 1024 channels/plane

    • Superb performance in high rates (>100 kHz/cm2)

      Spatial resolution ≈70 µm; time resolution 9 ns

  • T2K near-detector TPC readout

    • 72 chambers of 350 x 360 mm2

    • ‘Mass production’ using bulk micromegas technique

Joerg Wotschack (CERN)


The bulk micromegas technique
The bulk-micromegas* technique

The bulk-micromegas technique, developed at CERN, opens the door to industrial fabrication

Pillars (≈ 300 µm)

Mesh

r/o strips

Photoresist (64 µm)

PCB

*) I. Giomataris et al., NIM A 560 (2006) 405

Joerg Wotschack (CERN)


Bulk micromegas structure
Bulk-micromegas structure

Pillars (here: distance = 2.5 mm)

  • Standard configuration

  • Pillars every 2.5 – 10 mm

  • Pillar diameter ≈300 µm

  • Dead area ≈1–2%

  • Amplification gap 128 µm

  • Mesh: 350 wires/inch

  • Wire diameter 20 µm

Joerg Wotschack (CERN)


Early p erformance studies
Early performance studies

  • All initial performance studies were done with ‘standard’ micromegas chambers

    • We used different gas mixtures, initially Ar:CF4:iC4H10 (88:10:2, 95:3:2), moved later to Ar:CO2 (80:20, 85:15, 93:7)

  • The chambers were read out with the ALTRO chip (up to a maximum of 64 channels) and the ALICE Date readout system (Thanks to H. Muller and ALICE!)

  • End 2010 we switched to a new readout electronics (APV25, 128 ch/chip) and a new ‘Scalable Readout System’ (SRS) developed by H. Muller et al. in the context of RD51

P1 (40 X 50 cm2), H6 Nov 2007

Joerg Wotschack (CERN)


2008 demonstrated performance
2008: Demonstrated performance

  • Ar:CF4:iC4H10 (88:10:2)

  • Standard micromegas (P1)

  • Safe operating point with efficiency ≥99%

  • Gas gain: 3–5 x 103

  • Very good spatial resolution

250 µm

strip pitch

Inefficient areas

(MM + Si telescope)

y (mm)

σMM= 36 ± 7 µm

X (mm)

Joerg Wotschack (CERN)


Conclusions by end of 2009
Conclusions by end of 2009

  • Micromegas(standard) work

    • Clean signals

    • Stable operation for detector gains of 3–5 x 103

    • Efficiency of 99%, limited by the dead area from pillars

    • Required spatial resolution can easily be achieved with strip pitches between 0.5 and 1 mm

    • Timing performance could not be measured with the ALTRO electronics

  • However: sparks are a problem for LHC operation

    • Sparks lead to a partial discharge of the amplification mesh => HV drop & inefficiency during charge-up

    • The good news: no damage on chambers, despite many sparks

Joerg Wotschack (CERN)


2010 making mms spark resistant
2010: Making MMs spark resistant

  • Tested several protection/suppression schemes

    • A large variety of resistive coatings of anode

    • Double/triple amplification stages to disperse charge, as used in GEMs (MM+MM, GEM+MM)

  • Settled on a protection scheme with resistive strips

  • Tested the concept successfully in the lab (55Fe source, Cu X-ray gun, cosmics), H6 pion & muon beam, and with 2.3 MeV and 5.5 MeV neutrons

Joerg Wotschack (CERN)


T he resistive strip protection concept
The resistive-strip protection concept

Joerg Wotschack (CERN)


Large number of resistive strip detectors tested
Large number of resistive-strip detectors tested

  • Small chambers with 9x 9cm2active area

  • Large range of resistance values

  • Number of different designs

  • Gas mixtures

    • Ar:CO2 (85:15 and 93:7)

  • Gas gains

    • 2–3 x 104

    • 104 for stable operation

R16

R16, first chamber with 2D readout

Joerg Wotschack (CERN)


Small resistive strip detectors
Small resistive-strip detectors

Joerg Wotschack (CERN)


Detector response
Detector response

Joerg Wotschack (CERN)


Sparks in resistive chambers
Sparks in resistive chambers

  • Spark signals (currents) for resistive chambers are about a factor 1000 lower than for standard micromegas (spark pulse in non-resistive MMs: few 100V)

  • Spark signals fast (<100 ns), recovery time a few µs, slightly shorter for R12 with strips with higher resistance

  • Frequently multiple sparks

Joerg Wotschack (CERN)


Performance in neutron beam
Performance in neutron beam

  • Standard MM could not be operated in neutron beam

  • HV break-down and currents exceeding several µA already for gains of order 1000–2000

  • MM with resistive strips operated perfectly well,

  • No HV drops, small spark currents up to gas gains of 2 x 104

Standard MM

Resistive MM

Joerg Wotschack (CERN)


Spark rates in neutron beam r11
Spark rates in neutron beam (R11)

  • Typically a few sparks/s for gain 104

  • About 4 x more sparks with 80:20 than with 93:7 Ar:CO2 mixture

  • Neutron interaction rate independent of gas

  • Spark rate/n is a few 10-8 for gain 104

  • Larger spark rate in 80:20 gas mixture is explained by smaller electron diffusion, i.e. higher charge concentration

Joerg Wotschack (CERN)


Sparks in 120 gev pion muon beams
Sparks in 120 GeV pion & muon beams

  • Pions, no beam, muons

  • Chamber inefficient for O(0.1s) when sparks occur

  • Stable, no HV drops, low currents for resistive MM

  • Same behaviour up to gas gains of > 104

8000

Gain ≈ 4000

Gain ≈ 104

Joerg Wotschack (CERN)


Spatial resolution & efficiency in hadron and muon beamsS3 and R12 (250 µm strips)Analysis of data taken in July 2010 (by M. Villa)

Efficiency measured in H6 pion and muon beam (120 GeV/c); S3 is a non-resistive MM, R12 has resistive-strip protection

Spatial resolution as function of gain for S3 (non resistive) and R12 with resistive-strip protection

Resistive strip chambers fully efficient in a wide gain window

Resolution improves with resistive strips

Joerg Wotschack (CERN)


R11 rate studies
R11 rate studies

Gain ≈ 5000

Clean signals up to >1 MHz/cm2,

but some loss of gain

Joerg Wotschack (CERN)


Test beam nov 2010
Test beamNov 2010

Four chambers with resistive strips aligned along the beam

NEW: Scaleable Readout System (SRS) – RD51 (H. Muller at al.)

APV25 hybrid cards

Active area

9 x 9 cm2

Joerg Wotschack (CERN)


Apv25 data
APV25 data

Joerg Wotschack (CERN)


R11

R12

Charge (200 e-)

Time bins (25 ns)

R13

R15

ve ≈ 4.7 cm/µs

Strips (250 µm pitch)

Strips (250 µm pitch)

Joerg Wotschack (CERN)


R11

R12

Delta ray

Charge (200 e-)

Time bins (25 ns)

R13

R15

Joerg Wotschack (CERN)


Inclined tracks 40 tpc
Inclined tracks (40°) – µTPC

R11

Time bins (25 ns)

Charge (200 e-)

ve ≈ 2 cm/µs

R12

Joerg Wotschack (CERN)


And a two track event
… and a two-track event

R11

ve ≈ 2 cm/µs

Charge (200 e-)

Time bins (25 ns)

R12

Joerg Wotschack (CERN)


Ageing
Ageing

Joerg Wotschack (CERN)


Ageing studies
Ageing studies

  • Micromegas have shown excellent ageing properties in the past, no long-term effects were observed

  • However, no results are reported for MMs with resistive coating

  • We have started an ageing test campaign at CEA Saclay that involves high-rate exposure of resistive chambers to few MeV X-rays and thermal neutrons

Joerg Wotschack (CERN)


Long time x ray exposure 1
Long-time X-ray exposure 1

  • A resistive-strip MM (R17a) has been exposed at CEA Saclay to 5.28 keV X-rays for ≈12 days

    Accumulated charge: 765 mC/4 cm2

  • Expected accumulated charge at the smallest radius in the ATLAS Small Wheel: 30 mC/cm2 over 5 years at sLHC

    No degradation of detector response in the irradiated area (nor elsewhere) observed; rather the contrary (still to be understood)

Joerg Wotschack (CERN)


Long time x ray exposure 2
Long-time X-ray exposure 2

  • In a second measurement the same chamber (R17a) was exposed again to the X-ray source, irradiating a non-irradiated area of the chamber. In parallel an ‘identical’ chamber (R17b) was measured without being irradiated continuously. Exposure time: 21.3 days

    Accumulated charge: 918 mC/4cm2

Joerg Wotschack (CERN)


Exposure to thermal neutrons
Exposure to thermal neutrons

  • R17a was then moved to the Orphee reactor at Saclayand has been under radiation from 7 – 17 Nov 2011

  • Neutron flux is ≈0.8 x 109n/cm2/s with energies of 5–10 x 10-3eV

  • Total exposure on-time: 40 hrs equivalent to ≈20 years LHC at 5 x 1034 cm-2s-1 (including a safety factor of 3)

  • Exposure finished yesterday evening

  • Detector response perfectly stable over full duration of irradiation

Joerg Wotschack (CERN)


Two dimensional readout other structural issues
Two-dimensional readout &other structural issues

Joerg Wotschack (CERN)


2d readout r16 r19
2D readout (R16 & R19)

Mesh

  • Readout structure that gives two readout coordinates from the same gas gap; crossed strips (R16) or xuv with three strip layers (R19)

  • Several chambers successfully tested

Resistive strips

y strips

PCB

R16

y: 250/80 µm

only r/o strips

x strips

Resistivity values

RG ≈ 55 MΩ

Rstrip ≈ 35 MΩ/cm

x strips: 250/150 µm

r/o and resistive strips

Joerg Wotschack (CERN)


R16 x y event d isplay 55 fe
R16 x-y event display (55Fe γ)

R16 x

Charge (200 e-)

Time bins (25 ns)

R16 y

Joerg Wotschack (CERN)


R19 with xuv readout strips
R19 with xuv readout strips

  • Tested two chambers with same readout structure (R19M and R19G) in a pion beam (H6) in July

  • Clean signals from all three readout coordinates, no cross-talk

  • Strips of v and x layers well matched, u strips low signal, too narrow

  • Excellent spatial resolution, even with v and u strips

  • x strips parallel to R strips

  • u,v strips ±60 degree

Mesh

σ = 94/√2 µm

R strips

v strips

u strips

x strips

Joerg Wotschack (CERN)


Simplify construction of micromegas
Simplify construction of micromegas

  • Mesh

    • Mesh stretching over large-area is possible but complicates the production process

    • Mesh HV insulation requires special attention, work intensive

    • Mesh segmentation is difficult to achieve, dead areas, labour intensive

    • Two variants tried

      • Replace the mesh with a GEM foil

      • Connect the mesh to ground and the R strips to HV

  • Readout structure

RD51 Coll. Mtg, Joerg Wotschack (CERN)


Replacing the mesh by a gem foil gem is simply placed on 128 m high pillars on the resistive strips
Replacing the mesh by a GEM foilGEM is simply placed on 128 µm high pillars on the resistive strips

  • 2. Standard GEM foil

  • Works similarly as R19G

  • Did not find with this configuration a HV setting to profit from gain in GEM

  • Fragile, sparks in GEM destroyed GEM

  • 3. Stripped GEM foil (upper Cu layer removed)

  • Did not find good operating point

  • Works as MM but problems with GEM transparency

  • 1. Stripped GEM foil (lower Cu layer removed)

  • R19G, successfully used in test beam in July

  • Works well, no striking difference to 19M (with micromesh)

  • High rate looks OK

Effort not pursued any further

MPGD2011, Joerg Wotschack (CERN)


Inverting the hv connection scheme
Inverting the HV connection scheme

Drift electrode (-HV)

Resistive Strips (+HV)

  • Idea by A. Ochi (Kobe) ‘Why not connect the R strips to HV and the mesh to ground ?’

  • R20 was built along these lines

  • Simplifies considerably the detector production

  • Clean signals, good energy resolution

    • High gain

    • Little charge-up

    • Good high-rate performance

R20

Mesh

PCB

Insulator

Copper readout strip

Works very well, all recent detectors were built along these lines

MPGD2011, Joerg Wotschack (CERN)


Performance of r20 inverted hv
Performance of R20 (inverted HV)

55Fe γ (5.9 keV)

Ar:CO2 93:7

G≈5000

G≈10000

Signal drop: 5 % (compared to 10–15% for R11, R12,…)

8 keV Cu X-rays

Signal drop compatible with HV drop over resistive strips (0.5–1 GΩ)

MPGD2011, Joerg Wotschack (CERN)


Simplifying the readout board
Simplifying the readout board

  • Readout strips on two sides of PCB carrying the MM structure

  • PCB thickness 0.8 – 1 mm

  • Signals capacitively coupled across the PCB

  • No through holes

  • Connectors on both sides of the PCB

  • Avoids multi-layer PCBs

  • Leads to major simplification of production and cost reduction

  • Concept has been successfully tested in R21

Joerg Wotschack (CERN)


Towards large area mm c hambers
Towards large-area MM chambers

Joerg Wotschack (CERN)


Assembly of 1 st large resistive mm in march 2011
Assembly of 1st large resistive MM in March 2011

  • Size: 1.2 x 0.6 m2

  • 2048 circular strips

  • Strip pitch: 0.5 mm

  • 8 connectors with 256 contacts each

  • Mesh: 400 lines/inch

  • 5 mm high frame defines drift space

  • O-ring for gas seal

  • Closed by a 10 mm foam sandwich panel serving at the same time as drift electrode

Dummy PCB

Joerg Wotschack (CERN)


Cover and drift electrode
Cover and drift electrode

Joerg Wotschack (CERN)


Drift electrode hv connection
Drift electrode HV connection

HV connection spring for drift electrode

Al spacer frame

O-ring

seal

Joerg Wotschack (CERN)


Chamber closed
Chamber closed

  • Assembly simple, takes a few minutes

  • Signals routed out without soldered connectors

Joerg Wotschack (CERN)


Chamber in h6 test beam july 2011
Chamber in H6 test beam (July 2011)

Large resistive MM

R19 with xuv readout

(seen from the back)

Joerg Wotschack (CERN)


Experience with large 1 2 x 0 6 m 2 mm
Experience with large (1.2 x 0.6 m2) MM

  • The large MM with resistive strips and 0.5 mm pitch has been successfully tested in July and November in the H6 beam

Hit map showing the beam profile (top) and charge spectrum (bottom)

Event display showing a track traversing the CR2 chamber under 20 degree

Joerg Wotschack (CERN)


The 2 nd large resistive chamber
The 2nd large resistive chamber

  • Chamber was completed yesterday

  • Electrical tests are OK

  • Employs the new HV scheme with mesh on ground potential and resistive strips on +HV

Joerg Wotschack (CERN)


Micromegas in atlas cavern
Micromegas in ATLAS cavern

Joerg Wotschack (CERN)


Four resistive mms installed behind last muon station
Four resistive MMs installed behind last muon station

R13x

R16xy

R12

R11

Laptop

in USA15

≈120 mm

R16

DCS

mmDAQ

Joerg Wotschack (CERN)

Trigger (strips)


Collision data and cavern background
Collision data and cavern background

  • The chambers operated from April to November 2011

  • Most of the time collision data were recorded with a stand-alone trigger

  • In a few fills we recorded several 10 M events with a random trigger

  • For each trigger the detector activity was measured for 28 time bins of 25 ns, i.e. 700 ns (accepted 500 ns) over a total area of 2 x 81 cm2

  • Measured background rate: 2.7–3 Hz/cm2 at 1034 cm-2s-1

    About a factor 3 lower than the background rate measured in the nearby EOL MDT

Joerg Wotschack (CERN)


ATLAS cavern

Joerg Wotschack (CERN)


Two types of background events
Two types of background events

Total charge: 1700 ADC counts

Total charge: >10000 ADC counts

Photon ?

Neutron ? induced nuclear break-up

Joerg Wotschack (CERN)


Background rate 2 7 0 2 hz cm 2 at l 10 34 cm 2 s 1
Background rate ≈ 2.7±0.2 Hz/cm2 at L=1034 cm-2s-1

(Measured rate in close-by EOL2A07 MDT ≈ 8 Hz/cm2)

LHC luminosity (x1033 cm-2s-1)

Joerg Wotschack (CERN)


Conclusions
Conclusions

Joerg Wotschack (CERN)


What have we learned so far
What have we learned so far ?

  • Micromegasfulfil all of the Small Wheel requirements

    • Excellent rate capability, spatial resolution, and efficiency

    • Potential to deliver track vectors in a single plane for track reconstruction and LV1 trigger

  • We found an efficient spark-protection system that is easy to implement; sparks are no longer a show-stopper

  • MMs are very robust and (relatively) easy to construct (once one knows how to do it)

  • Large-area resistive-strip chambers can be built … and they work very well

Joerg Wotschack (CERN)


What next
What next?

  • We are working on a detector of 1.2 x 0.5 m2 with four active planes to be installed in the winter shutdown in ATLAS on the Small Wheel on one of the CSCs

  • Install a small detector (MBT0) in front of the end-cap calorimeter as prototype for a replacement of the Minimum Bias Scintillator trigger detector

  • Build a 1m wide chamber (possible after the completion of the upgrade of the CERN PCB workshop, early 2012 ?)

  • Move to industrial processes for

    • Resistive strip deposition

    • Mesh placement

      … and build a full-size module0 for the Small Wheel in 2012

Joerg Wotschack (CERN)


Thank you !for your attention… and thanks to the many colleagues who in one or the other way helped with our micromegas R&D project

Joerg Wotschack (CERN)


Backup slides
Backup slides

Joerg Wotschack (CERN)


A tentative Layout of the New Small Wheels and a sketch of an 8-layer chamber built of two multilayers, of four active layers each, separated by an instrumented Al spacer for monitoring the internal chamber deformations

Joerg Wotschack (CERN)


Homogeneity and charge up
Homogeneity and Charge-up an 8-layer chamber built of two multilayers, of four active layers each, separated by an instrumented Al spacer for monitoring the internal chamber deformations

R ≈ 45 MΩ

R ≈ 85 MΩ

  • No strong dependence of effective gain on resistance values (within measured range)

  • Systematic gain drop of 10–15% for resistive & standard chambers; stabilizes after a few minutes

  • Charge-up of insulator b/w strips ?

Joerg Wotschack (CERN)


Trigger readout
Trigger & readout an 8-layer chamber built of two multilayers, of four active layers each, separated by an instrumented Al spacer for monitoring the internal chamber deformations

  • New BNL chip: 64 channels; on-chip zero suppression, amplitude and peak time finding

    • Trigger out: address of first-in-time channel with signal above threshold within BX

    • Data out: digital output of charge & time for channels above threshold + neighbour channels

  • Trigger signals and data are driven out through one (same) GBTx link/layer (one board/layer)

    • Trigger: track-finding algorithm in Content-Addressable Memory (or in FPGA) in USA15; latency estimated 25–32 BXs (of 42 allowed)

    • Small data volumes thanks to on-chip zero-suppression and digitization

Joerg Wotschack (CERN)


Trigger/DAQ Block Diagram an 8-layer chamber built of two multilayers, of four active layers each, separated by an instrumented Al spacer for monitoring the internal chamber deformations

GBTx Gigabit Tranceiver

Chipset being developed at CERN, will combine

Data, TTC, DCS on a single fiber

Joerg Wotschack (CERN)


Bnl chip specifications prelim
BNL chip an 8-layer chamber built of two multilayers, of four active layers each, separated by an instrumented Al spacer for monitoring the internal chamber deformationsspecifications (prelim.)

64 channels/chip (preamplifier, shaper, peak amplitude detector, ADC)

  • Real time peak amplitude and time detection with on-chip zero suppression

  • Simultaneous read/write with built-in derandomizing Buffers

  • Peaking time 20–100 ns; dynamic range: 200 fC

  • Fast trigger signal of all and/or groups of channels

  • Rate: 100 kHz

  • SEU tolerant logic

    A similar older BNL chip (with longer integration time and smaller rate capability) has been tested with our MMs and is working well

Joerg Wotschack (CERN)


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