Digital Hadronic Calorimeters Imad Laktineh Institut de Physique Nucléaire de Lyon.
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Transcript of Digital Hadronic Calorimeters Imad Laktineh Institut de Physique Nucléaire de Lyon.
Digital Hadronic Calorimeters
Imad Laktineh
Institut de Physique Nucléaire de Lyon
Outline
• Some History
• Why digital hadronic calorimeters are good for ILC
• Gaseous detectors for the DHCAL
• DHCAL present Activities
• Towards the technological prototype
Some historyThe use of gaseous detector as a sensitive medium in calorimeters is not a new idea. Calorimeters based on gaseous detectors using proportional, saturated avalancheand streamer modes were developed since the seventies of the last century. In some cases digital readout (counting the number of tracks the shower) were used.
Example : PEP4 Electromagnetic Calorimeter Gaseous (argon-Ethyl-bromide) Geiger cells+ Lead Resolutions obtained with gaseous calorimeters were shwon
to be equivalent to those obtained with scintillators calorimeters.
PEP4 experiment scheme
PEP4 ECAL scheme
Linearity of gaseous calorimeter
Some examples of gaseous HCAL
: The four LEP experiments at CERN (ALEPH, DELPHI, L3, OPAL) had their hadronic calorimeters or part of it made with gaseous detectors:
ALEPH : Iron + Streamer tubes 85%/√E
DELPHI :Iron + Streamer tubes (only barrel) 21%+112%/ √ E L3 : Uranium +Wire chambers
OPAL : Iron + Streamer tubes 120%/√E
ATLAS combined beam test :σ/E ≈ (0.52/√E + 0.03/E) + 1.6/E (LAr + Tile)Expected jet energy resolutionσ(jet)/E ≈ 0.6/√ E(GeV)
CMS-brass-scintillator readout by wavelength shifter in the barrel and endcaps-Fe-quartz fibers (Cerenkov) in the very forward directionATLAS-Fe-scintillator tile / WLS fibre readout in the barrel-Cu/Liquid Argon in the endcap-W/Liquid Argon in the very forward region
At LHC with very high energy jets the non linearity of the standard gaseous calorimeters would have been a problem
Why Digital HCAL For ILC?
Jet energy resolution is a key feature of the future Linear Colliders experiments
Zqq (70%), Wqq’(68%), H(120 GeV)qq,WW,ZZ (85%)
Improving jet energy resolution is of important interest for bosons identification
60%/E 30%/E
Motivation
Charged tracks resolution ∆p/p ~ few10-5 Photon(s) energy resolution ∆E/E ~ 12% Neutral hadrons energy resolution ∆E/E ~ 45%
Ejet = Echarged tracks + E + Eh0fraction 65% 26% 9%
2 jet = ch. + 2 + 2 h0 + confusion
= (0.15)2 EJet + confusion
PFA: Particle Flow Algorithms : High granularity Topological separation Reduce confusion Improve on jet energy resolution
Motivations
Ed
ep
Nh
its
E pion (GeV) E pion (GeV)
Digital-1bitAnalog
Gaussian
E (GeV) Number of hits
/mean ~22% /mean ~19%
++ 5GeV 5GeV
Simulation
Magill
Comparison analog%digital
Sandwich
Hadron Calorimeter
incident
lead 1m×1m×8mmsci 1m×1m×2mm
×100 Layers
・・・
1m×1m
1mYamada et al
Analog
lead 1m×1m×8mm
sci 1m×1m×2mm
×100Layers
measure all energy
each layer
Measure Energy
Digital
lead 1m×1m×8mm
sci 1cm×1cm×2mm
×10000
×100Layers
measure number
of all hits
NhitYamada et al
Histogram of π( 4GeV 、 1000event )
analog digital
Mean : 113.9MeVSigma : 34.43MeV
Mean : 35.59hitsSigma : 9.027hits
Yamada et al
Threshold Dependence(Nhit)
electron π
Yamada et al
Measure Energy , Nhit( Incident Energy Dependence )
analog digital
Yamada et al
Energy Resolution( Incident Energy Dependence )
electron π
Yamada et al
Cell Size Dependence( Measure Energy , Nhit )
electron π
Yamada et al
Cell Size Dependence( Energy Resolution )
electron π
Yamada et al
Matsunaga et al
Matsunaga et al
Why Gaseous HCAL For ILC?
0.1
1
10
100
1000
0 20 40 60 80 100
z position ( cm )
Hit
tim
e (
ns
)pi-4GeV
The green cells are neutron hits. (by G4Track Information)
E(neutron) = 50MeV
Z
The hits are due to neutron scattering.
Takeshita et al
Single pion simulation
Neutrons
Neutrons
Scintillator Gas(Xenon)neutron 50MeV
The box size: 1m x 1m x 1m
Neutrons incident at random positions to the pure scintillator and the gas. Takeshita et al
Homogeneity
The detector is segmentedEffect to be measured
Segmentation is provided by the readout. No effect observed
Why Gaseous Digital HCAL For ILC?
Calibration
The calibration is an important issue in case of high granular analog scintillator HCAL :
•SiPM output dependence on temperature and voltage •Scintillator and fiber evolution with time (forward regions)•Electronics readout system
In the case of gaseous digital HCAL only electronics readout system needs to be calibrated and it is very simple for digital or semi-digital readout.
Analog
HCAL 85%/√E 21%+112%/ √ E 120%/√E
Digital
DHCAL For ILC
ILD with GRPC
DHCAL For ILC
SiD with GRPC,GEM,MICROMEGAS
Energy resolution of K0-L in the ILD DHCAL Barrelwith 1-bit readout using PANDORA
Gaseous Detectors For DHCAL
• GRPC
• GEM
• MICROMEGAS
Gaseous detectors
ln M
Voltage
Attachment
Collection
Multiplication
StreamerBreakdown
IONIZATION CHAMBER
PROPORTIONAL COUNTER
Saturation
n1
n2
Sauli@tipp09: http://kds.kek.jp/conferenceTimeTable.py?confId=2376
Gaseous detectors
M (x) nn0
e x
Sauli@tipp09: http://kds.kek.jp/conferenceTimeTable.py?confId=2376
QMAX ≈ 107 e SPARK
Gain:
= N (Townsend coefficient)
Raether limit
lE x
Ions
Electrons
fast
slow
GRPC Glass Resistive Plate Chamber1981: Santoninco,Cardarelli
Avalanche modeHV=6-8 KV/mmTFE+IB+SF6Gain about 106
Streamer modeHV>8 KV/mmArgon+IB+SF6Gain about 108
glass
glass
glass
No spark : V = R I with R very high
GEM 1996: F. Sauli: Gas Electron Multiplier (GEM)
500 V on the 2 copper sides of the kapton foil of 50 µ E 100 KV/cminto the holes
Gain 102-103 / foilGas mixture dependent
1996 : MICRO MEsh GASeous detectorY. Giomataris, Ph. Rebourgeard, J.-P. Robert, G. Charpak,
or pads
MICROMEGAS
300-400 VBetween the mesh and the pickup padsD= 50-120 µ In the Multiplication space E 60-100 KV/cm
Gain = 104-105
Gas mixture dependent
GRPC GEM MICROMEGAS
Cost low high high
Efficiency high high high
Multiplicity 1.1-1.8 1.05-1.1 1.07-1.15
Charge(pc) 0.1-10 .002-.5 .002-.5 Rise time few ns few ns few ns
Sparks absent moderate frequent
Detection rate < 100Hz/cm2 high high
Thickness < few mm <few mm < few mm
Fabrication simple complex complex
DIGITAL HADRONIC CALORIMETERS DEVELOPMENT in CALICE
µMEGAS-based DHCAL development
The detector development is realized essentially by the LAPP group
• Setup– 6 x 16 cm2 mesh– Source collimated above 1
pad– Readout mesh signals
• Collection efficiency– Plateau for field ratios
larger than 50
• Gas gain (assuming 230 primary e-)– Gain doubles every 20 V– Decreases with pressure– Max around 2.104
• Energy resolution at 5.9 keV– 17 % FWHM
Slope yields -2 fC/mbarA
DC
Cou
nts
Pressure (mbar)
55Fe X-ray source test
Beam test setup• Trigger: 3 scintillators• 3 Micromegas 6x16 pads• 1 Micromegas 12x32 pads• Steel absorber option
• GASSIPLEX readout– VME modules (ADC) +
CENTAURE
• Characterisation of the prototypes– efficiency and multiplicity– response uniformity over area– X-talk studies
• Aug & Nov 2008 at CERN PS and SPS
H2 line at SPS-CERN(4th August-15th August 2008)
• Select event with one and only one hit in each chamber– Insure all charge collected on
one pad– Hit if ADC > 27 counts
• Landau distribution MPV is at 45 fC– Shows variations of 10% RMS
over all pad platinum events
MPV ~ 45 fC
en
trie
s
all triggers
ADC counts
Chamber 0Chamber 1Chamber 2Chamber 3
2.7 fC
Efficiency and multiplicity• Require one and only one « safe » hit in
three chambers– ADC > 51 counts (5.3 fC)– Hit position in fourth chamber
extrapolated– Count hit (ADC > 27 counts) in 3x3
pad area
• Efficiency between 92 and 99 %• Multiplicity between 1.07 and 1.15
Efficiency map of one chamber
gold events
Hit multiplicity distributions of 2
chambers
Micromegas with Digital readout
• PCB with DIRAC1 64 channels ASIC – Digital link to DAQ (possibility to chain detectors)– 3 thresholds – Synchronous architecture
• First operational Bulk Micromegas with embedded readout electronics !
DIRAC
Sparks protections mask for bulk laying 8x8 pads with bulk
Bulk from R. De Oliveira & O. Pizzirusso
Micromegas with digital readout
• Tested during August 2008 test beam• Minimum threshold of 19 fC• Only one detector available
– No efficiency/multiplicity measurements yet
– Prepare more prototype for next beam test
Beam Profilewhen moving the X-Y table
Micromegas with digital readout
• PCB with 4 HARDROC1– 64 channels ASIC, detector active area 8x32 cm2
sparks protections
HARDROC1
bulk
Some problems withthe mesh HV but analysisIs going on
2008 beam test setup is being simulated to Compare
with real data
30 cm iron absorber in front
Simulation
Test beam
1 m² prototype: 6 Active Sensor Units9 216 channels - 96 x 96 cm² active area - 3 DIF + interDIF boards
Expected in the second half of 2009
DHCAL with Micromegas
• Full 1 m² geometry implemented– Readout: from 0.5 x 0.5 cm2
to 4x4 cm² pads– 3 mm drift gap– Gas mix. Argon/Isob. 95/5– 1.9 cm thick absorber
between layers– different absorber materials– 40 or 80 layers (~4, 5 or
~9 λ)– Thickness of active layer: 3.2
mm
– Ideal Micromegas, digitization not yet fully implemented
DHCAL 40 planes
100 GeV Pions
• Sum up hits and energy in all cells• Apply a single threshold (1 MIP)• Look at distributions RMS
E(GeV)
Nb
of H
its
1 MIP thresholdPions
Nb of Hits
Nb
of e
vent
s
Nb of Hits
Nb
of e
vent
s
Analogresponseat 10 GeV
Digitalresponseat 10 GeV
1 MIP threshold
Energy resolutionPion energy
E (GeV)
σE/E
Worse resolution at High energy Need more than 1 threshold ?
GEM-based DHCAL development
The detector development is realized essentially by the UTA group
Feb. 20, 2009 63
GEM-based Digital Calorimeter Concept
Use Double GEM layers
{~6.5mm
-2100V
∆V ~400V
∆V ~400V
0V
GEM DHCAL Status & Plans J. Yu
1cmx1cm readout pads
GEM 30cmx30cm Foil Mounting Jig
Anode Board & Preamp for 30cm x 30cm Chamber
Preamps configured to read 96 pads in the center
Use 32 channel FNAL preamps
30cmx30cm D-GEM Detector Signal
Signal from Cs137 Source
30cm x 30cm GEM Chamber for KAERI Beam Exposure
UTA GEM Chamber in KAERI Electron Beam
4-pad area (2cm x 2cm) exposed to scanning beams for ~2000 sec.
•e- beam: 1010 particles in 30ps pulse ~every 43s
•Scans 4cmx60cm area every 2 seconds
G10 boards in the exposed area discolorized.But no damage to the GEM foils
GEM Beam Test Detector Setup
3 Slice test finger counters
Slice test 19x19cm2
counter
30x30cm2 GEM chamber
Slice test 19x19cm2
counter
• Beam Trigger – 5Fold scintillation counters
– Three 1cmx1cm finger counters, 5cm apart, upstream – Two 19cmx19cm counters envelop the chamber active
area, separated by about 3m’s, downstream – Coincidence of all 5 counters defines a beam spot less
than or equal to 1cmx1cm -->Size of one readout pad
• GEM Chamber self trigger – Use negative chamber output – Threshold set at -30mV
• Beam constrained chamber trigger formed of 5F*GEM: 6Fold
– Allows to look at data from neighboring pads while triggering on the pad centered at the beam
– Had to use this since there were no independent means of ensuring the beam containment in one pad
Signal shape Efficiency
GEM with Analog KPix Chip
M. Breidenbach/R. Herbst SLAC
1cmx1cm cells
KPiX (64-ch, developed for ILC Si-Ecal) was modified to accommodate
smaller GEM signals (>~20fC)
10cm x 10cm Pad Board Test Chamber
KPiX chip uses ILC-clock synchronization. No external trigger system. This is not appropriate to measure efficiency in test beams or cosmic ray data taking.
New version (KPiX v7) includes an external trigger
Right under the sourceAway from the source
KPiX4-GEM Source Response Extraction
• A method based on simulation developed to overcome the triggering complication with weak source Jacob’s Method
• Simulate KPiX4 readout of GEM signal using GEM pulse signal, actual pedestal distributions and previously measured Landau response curves– Since the source signal is random, KPiX integrates charge
partially• Let the Landau MPV and width as well as the normalization of
the ped gaussian float till the source data is well described by the simulation
Feb. 20, 2009 GEM DHCAL Status & PlansJ. Yu
76
Extracted Response – GEM-KPix
MPV=1.9fC (normally ~20fC)
DataSimulationResponse
Random sampling of signal & inadequate gas supply
Charge (fC)
Base steel plate, t=2 mm
Readout Board330x500 mm2
330 mm
1000 mm
UTA’s 33cmx100cm DHCAL Unit Chamber
GEM DHCAL Future Plans
Late 2009 – Mid 2011– 33cmx100cm thin GEM unit chambers
• Complete production of 15 33cmx100cm unit chambers
– Construct five 100cmx100cm GEM DHCAL planes• Using DCAL or KPiX readout chips
– Beam test GEM DHCAL planes in the CALICE beam test stack together with RPC
– TGEMs and RETGEMs• Construction and characterization of a prototype
chamber using an analog readout chip• Beam test of TGEM prototype chamber
UTA’s 100cmx100cm Digital Hadron Calorimeter Plane
Feb. 20, 2009 79GEM DHCAL Status & PlansJ. Yu
RPC-based DHCAL development
Efforts in the U.S
Efforts in Europe&Asia
GRPC DHCAL Activities in U.S
The detector development is realized essentially by the ANL group
I Resistive Plate Chambers
Pursued two design options
Two-glass design
One-glass design
Resistive paint
Resistive paint
Mylar
1.2mm gas gap
Mylar Aluminum foil
1.1mm glass
1.1mm glass
-HV
Signal padsG10 board
Resistive paint
Signal pads
Mylar
Aluminum foil
1.1mm glass1.2mm gas gap -HV
G10 board
Vertical Slice Test
Test of whole system with
20 x 20 cm2 GRPC 9 2-glass designs 1 1-glass design Only use RPC0 – RPC5 in analysis of e+, π+
Only use RPC0 – RPC3 for rate dependence Absorber For cosmic rays, muon, pions, electrons: Steel (16 mm) + Copper (4 mm) Rate capability measurement (120 GeV protons): 16 mm PVC with whole cut out in centerTest beamPrimary beam (120 GeV protons) with beam blocker for muonsPrimary beam without beam blocker for rate measurementsSecondary beam for positrons and pions at 1,2,4,8, and 16 GeV/c
Electronic Readout System
Attempt to be as similar as possible to what’s needed for the PS
Components
DCAL ASIC ANL/FNAL Pad-boards ANL Front-end boards ANL Data concentrators ANL Data collectors Boston Timing and trigger module FNAL
Prototyping and commissioning
Used 2nd round of DCAL prototypes All other components: 1st prototypes → all worked very well
A few events… μ Calibration Runs120 GeV protons with 1 m Fe beam block no μ momentum selection
One of many perfect μ event
μ event with double hits in x
μ at an angle or multiple scattering
μ event with δ ray or π punch through
A few events…e+ Run 1 - 16 GeV secondary beam Čerenkov signal required
8 GeV e+ event
8 GeV e+ event with satellites 8 GeV e+ event
8 GeV e+ event
A few events…π+ Run 1 – 16 GeV secondary beam Veto on Čerenkov signal
8 GeV π+ event (typical)
8 GeV π+ event (early shower)8 GeV π+ event (early shower)
8 GeV π+ event (early shower)
Efficiency = ___________________ All triggers
Events with hits in RPC
At high rate efficiency drops and then levels out
Fits to exponential + constant appear adequate
Time constant for efficiency drop shorter at higher rate (as expected)
Efficiency drops for rates ≥ 100 Hz/cm2
In agreement with previous measurements with sources
Simulation Strategy
• Generate muons (at some energy) with GEANT4 (with same x-y distribution and slope as in the data)
• Get x,y,z of each energy deposit (point) in the active gaps• Generate charge from measured charge distribution for each point (according to our own measurements)
• Introduce charge offset Q0 for flexibility• Introduce dcut to filter close-by points (choose one randomly)
(RPCs do not generate close-by avalanches) • Noise hits can be safely ignored
• Distribute charge according to exponential distribution with slope a• Apply threshold T to flag pads above threshold (hits)• Adjust a, T, dcut and Q0 to reproduce measured hit distributions
• Generate positrons at 8 GeV with GEANT4 (with same x-y distribution and slope as in the data)
• Introduce material upstream to reproduce measured shapes etc… • Re-adjust dcut if necessary (Muon data not very sensitive to dcut)
• Generate predictions for other beam energies• Generate pions at any beam energy
Lateral shower profile
Without material in beam
First layer too narrow
Subsequent layers OK
Data
Simulation
Lateral shower profile
With lots of material (1/4 X0) in beam
Looks good everywhere
Data
Simulation
1 m3 – Physics Prototype
Description 40 layers each ~ 1 x 1 m2
Each layer with 3 RPCs, each 32 x 96 cm2
Readout of 1 x 1 cm2 pads with one threshold (1-bit) ~400,000 readout channels using the same electronics as the one or the VST Layers to be inserted into the existing Calice AHCAL structure
Purpose
Validate DHCAL concept Gain experience running large RPC system Measure hadronic showers in great detail Validate hadronic shower models
Status Started construction in fall 2008 DCAL chips ok but pacjaging is on critical path GRPCs : Adequate glass, resistive painting, cassetes : ongoing Completion is expected by end of 2009
RPCs and cassettes
RPC design
2 – glass RPCs 1 – glass RPCs (developed by Argonne)
Prototypes
Number of RPCs
Number of glass plates
Glass thickness [mm]
Size [cm]
Status Tests Problems
~15 2 1.1 20 x 20 built 2 years None
1 1 1.1 20 x 20 built 2 years None
1+3 2 1.2 32 x 96 built 1 month High pad multiplicity
3 1 1.1 20 x 20 built 2 months None
2 2 0.85/1.2 32 x 96 being built
Not on critical path
Comment I: Glass thickness
Pad multiplicity of 32 x 96 cm2 too large: due to glass of 1.2 mm (and track extrapolation) Difficulty to obtain 0.85 mm glass in the U.S. Vendor from Europe identified, provided 10 samples
Comment II: 1 – glass RPCs
Advantages: pad multiplicity ~1, thinner, simpler, surface resistivity not critical, better rate capability, compression with electric field Disadvantage: can’t be assembled without final electronics, recent design (less tested) Some layers for the physics prototype will be equipped with 1 – glass RPCs
Comment III: Resistive paint
LICRON paint (we all used for years) not available anymore New LICRON product difficult to apply (backup solution) Explored two alternatives
Artist paint (currently preferred solution)Floor paint (possible solution)
Black-Green Artists PaintX 1 = 20% HumidX 4 = 20% HumidX 5 = 60% Humid
0
0.5
1
1.5
2
2.5
3
0 2 4 6
TIME ( Test Number )
Res
ista
nce
,
ME
G
Left side
Right side
Center X
Center Y
GRPC DHCAL Activities in Europe & Asia
Bologna-CERN,IPNL,LAL,LLR,Louvain-la-Neuve,Protvino,Tsinghua
RPC in avalanche mode(TFE/Iso/SF6 = 93/5/2)1.2 mm,8.4 kV - working point,2.2 mV thr
Protvino
The challenge for ILC DHCALHow to have a detector of few thousands m² fully equipped with low consumption semi-digital readout and still very compact !!!!?Embedded Daisy-chained electronics can be the solution
VFE ASIC
DataADC
I/OBuffer
FE-FPGA
BOOT CONFIG
Data FormatZero SuppressProtocol/SerDes
FPGA Config/Clock Extract
Clock
Bunch/Train Timing
Config Data
Clk
SlabSlab
FEFPGA
PHY
Data
Clock+Config+Control
VFEASIC
Conf/Clock
VFEASIC
VFEASIC
VFEASIC
RamFull
Analog output
HARDROC
• 64 channels, 16mm²• Digital/analog output.• 2bit: 2-3 thresholds• low consumption, power pulsing (< 10 µW/ch)
Electronics
30 fC
10 fC
Piedestal
Dac
un
it
chanel
•Digital memory able to store up to 128 evts.• Large gain range • Xtalk <2% Adequate for GRPC* (threshold>10 fc)
Mini DHCALMini DHCAL project projectAim: Validate the new electronics/acquisition scheme for theDHCAL
(GRPC/ µMEGAS)•8-layer, 800 µ thick PCB buried and blind vias x-talk <0.3 %•4 hardroc chips •Readout FPGA USB•8×32 pads detector
FPGAasics
Acquisition modes : different modes are allowed:
a) Triggerless (ILC mode)
b) External trigger : cosmic rays & test beam
Data output: digital and analogue
First Daisy chain measurement
LLR
before
after
Gain correction
2.5 fc
Injected charge = 100 fc
8x32 pads prototypes
Example of a recorded mip
5-GRPC cosmic rays test bench
1st GRPC
2d GRPC
3d GRPC
4th GRPC
5thGRPC
Hit pads
Pads associated to the 4 asics
second threshold
First threshold
Threshold 100 fc, gas mixture :TFE(93%,Isobutane 5%, SF6 2%)
Resistive painting Graphite(400 k)
Resistive painting Licron(20 M/)
X-talk [email protected] kv
X-talk [email protected] kv
GRPC
GRPC
Test Beam @PS-CERN
Goals :
• Validate the semi-digital electronics readout system in beam conditions
• Evaluate the performance of different kinds of GRPCs
PS T10 17-24 july: (260 kEvents)PS T10 17-24 july: (260 kEvents)
• Use of Eudet telescopeEudet telescope with 4 graphite GRPC from protvino. Track reconstruction (accuracy <100μm of one telescope 100μm of one telescope armarm) to evaluate efficiency at interpad and edges
• Hight voltage scanHight voltage scan monitoring efficiency/multiplicity.
• Record first pions showerspions showers with miniDHCAL configuartion (use of iron slabs).
• Test of new GRPC prototypesnew GRPC prototypes over different angles (GRPC licronlicron, GRPC staguardstaguard).
PS T9 28 July 4 august (80 kEvents)PS T9 28 July 4 august (80 kEvents)
• Record more pions showers, with different slab different slab configurationsconfigurations.
• Test again new GRPC prototypes (GRPC licron, GRPC staguard).
PS T9 7-12 November (65 kEvents)PS T9 7-12 November (65 kEvents)• First test of multigap GRPC multigap GRPC (could reduce charge spread)
• Flux and detector ratesdetector rates testing (20-6000 triggers/spill)
• First attempts : replacing isobutane by COCO22.
All evtsAll evts
dt >50 msdt >50 ms dt >50 msdt >50 ms
Previous spillPrevious spill Current spillCurrent spill
NoiseNoise0.045 Hz/cell0.045 Hz/cell
Efficiency map for 3+1 GRPCs @7.4KV
Dead channels
Daq’s Thresholds: lower 120 fC 120 fC / higher 450fC 450fC Plateau: 7.2 to 8 kV 7.2 to 8 kV
-> Efficiency between 80 and 98%80 and 98% Lower multiplicity will be the best for us.
-> Best ratio Best ratio multiplicity/efficiency: around 7.4 kVaround 7.4 kV Until now the licron detectorlicron detector seems to be the best candidate:
-> it got the lower multiplicity and shows acceptable efficiency performances.
Multiplicity moving as expectedmoving as expected => lowering as threshold increase. Efficiency decreasing a bit (about 12%). ASIC’s dynamic range to short to have à kind of MIP spectraMIP spectra.
Next ASIC version will have a larger dynamic rangelarger dynamic range, so we can make this measurement again.
Eudet Telescope
Moveable table
photogrammetric spotsused for alignment
I.Laktineh-IPNL 112
Spots positioning on both EuDet telescope and DHCAL Setup
Using EuTelEuTel, we can evaluate efficiencyefficiency on the detector edgesedges, and between two pads.
Black (Trigger): spatial prediction of hits in GRPC, from EuTel.
Red : matched digital hits (EuTel + GRPC)
Efficiency:Efficiency: Red/Black
Angle scan:Angle scan:
Efficiency quite constantquite constant, even forlarge angles
Fvolution of performances with particle flux :Fvolution of performances with particle flux : Correlation with particle particle
flux flux (obtained with scintillators ), and chamber’s efficiency.
It gives us some preliminary results about GRPC running in ILC beam conditionsILC beam conditions.
96%
The firsts tests using COCO22 to replace isobutane are quite promising.
(Gas mix with C02 will be intensively testedintensively tested next test beam)
Hadronic shower are mostly uncontainedmostly uncontainedin MiniDHCAL (0.5 i)but these profiles gives a first ideafirst idea of shower development,and energy deposition.
Hadronic showersHadronic showers
BeamGRPCsGRPCs
GRPC 1GRPC 1
GRPC 2GRPC 2
GRPC3GRPC3
GRPC4GRPC4
Muon contamination area
Beam(pions)
Blue: 1st threshold
Red: 2d threshold
TILC09 April 17-21 Tsukuba
Distribution of total number of hits in mini DHCAL for test beam datatest beam data and geant4 simulated datageant4 simulated data.
PreliminaryPreliminary
Muon contamination area
Preparation for the technological prototype
Technology drivers :• Closed chamber design – no external gas-tight box• Reduce the dead zones: spacers, frame• uniform resistive coating • Low cost• ScalableComponents Borosilicate glass
Anode: 0.7 mmCathode: 1.1 mm
Resistive layer (~ 20μ)Graphite, Licron’ (polymer), Statguard’ (oxides of Fe, Ti)
Insulation layers – mylar:175 μ cathode side (HV ~7.5 kV)50 μ anode side (0 V)
GRPC activities
1M2 for the technological prototype
• Two types of chamber:– ‘Standard’ chamber
• Frame in G10, thickness 1.2 mm, width 3 mm• ‘Channelled’ gas distribution – ‘2 fishing lines’ (PMMA)
– ‘Capillary’ chamber• Capillary tube frame 1.2X.8 mm• Frame used to distribute gas (0.3 mm holes drilled in capillary
walls)• Advantage: reduction of dead zones
• Support between glass planes:– Ceramic balls diam. 1.2 +/- 0.02 mm– Distance between balls optimized (ANSYS): 100 mm (max. deformation 44 μ – 81 balls / m2)
Mechanical deformation of the detector
Deformation with HV and ceramics balls
Gas pressure reduces this
Gas distribution, ‘standard’ chambersGas distribution, ‘standard’ chambers
Simulation – gas circulation in standard chamber
Gas distribution,‘capillary’ chambers
Capillary 1.2 x 0.8
Anode glass
Cathode glass
PEEK capillary
PEEK joint
Gas distribution holes ∅= 300 microns
Simulation – gas circulation in capillary chamber
M2 GRPC Status4 chambers of 1M2 were built up to now in Lyon • All with the standard gas distribution system
• 2 with Licron (aerosol ,ρs ~ 30 MΩ/□)
• 1 with Statguard ( liquid, 500 MΩ/□ !!!!!)• 1 to be coated with Statguard (silk screen printing)
Three kinds of problems were encountered and solved:• Gas tightness
• High voltage connection
• Resisitivity control
Construction steps
– Clean glass and cover with resistive coating– Glue micro-balls, frame, gas spacers and capillary
tubes to cathode glass on gluing table– Add glue to upper surfaces of balls and gas spacers– Turn table to vertical position– Introduce anode glass– Turn table to horizontal position– Deposit glue lines between glass and frame to
make gas-tight– Glue 6mm gas connectors to capillaries and solder
HV connectons– Transfer to honeycomb support
Gas tightness
• First chambers inflated under gas pressure!
• Glue failure caused balls to become detached from upper glass
• Subequent failure of glue around perimeter → gas leaks
• Over-pressure in chamber not excessive (Δpexit ~2.5 mbar ≡ 250g / ball max.)
deltaP capillaire
0,00
0,20
0,40
0,60
0,80
1,00
1,20
1,40
1,60
1,80
2,00
0 0,5 1 1,5 2 2,5 3 3,5 4 4,5
Débit (l / hr)
Del
ta P
(m
bar
)
Glue test
• Usual glue – two-component epoxy AY103 + HY951: 2.7g/cm2• Dow Corning RTV Silicone 3140: 5.0g/cm2• Araldite epoxy 2011 / 2012: 108 g/cm2
HV connections
• Recurring problem – loss of HV connection on Licron chambers
• Apparent thinning of Licron layer near the copper strip glued to the glass
• Occurred using: After short time (few days to a couple of weeks)– Copper Scotch with conductive adhesive– Copper strips glued with silver-loaded varnish
• Solutions found:– Graphite Scotch– Epotek EE129 conductive epoxy
Both solutions seem to work up to now
Statguard resistivity (1)
• Commercial product used for ESD protection of floor surfaces
• Potential to silk-screen print onto glass• Relatively inexpensive• Good surface finish• Small chamber in Nov. 08 test beam performed
reasonably well (efficiency, multiplicity) Vincent talk
• 1M2 Statguard chamber in same test beam had static build-up problem → few HARDROCs damaged due to charge breakdown
This is due most probably to the very high Statguard resistivity (500MΩ/□ )
Statguard resistivity (2)
• Resistivity not easily controllable:– Varies from 10 MΩ/□ to >500 MΩ/□ for no
apparent reason– Same glass cleaning procedure– Same method of deposition (roller)– Same number of layers and approximate layer
thickness• Recent tests indicate roller may be to blame• Consistent results (~25 MΩ/□ for 1 coat) with
paint brush or skimmer• Silk-screen printing method has been investigated
Silk-screen printing method
• Silk-screen printing method provides a uniform thickness.• Suitable for coating of large surface detectors • Different screen configurations were tested using Statguard to obtain the needed resistivity• other coatings will be tested (colloidal graphite)
Resistivity evolution with time after silk-screen painting
• Resistivity depends on the layer thickness (up to some extent) • Using the screen structure allows to determine the thickness (less fibers/cm more paintingthicker layerless resistivity)
Statguard painting
GRPC activitiesMGRPCBologna-CERN(C.Williams)
•5 glass plates of 400 µ each4 gaps of 250 µ using fishing line as spacersand Licron as resistive coating
•32X8 cm2 MGRPC was built and tested with the SDHCAL electronics
•1M2 multigap GRPC is beingbuilt and will be tested with the same 1M2 SDHCAL electronics
Cathode -10 kV
Anode 0 V
(-2 kV)
(-4 kV)
(-6 kV)
(-8 kV)
Signal electrode
Signal electrode
10 11 12 13 14
1000
100
10
1
Applied Voltage [kV]
2 mm gap RPC with C2F4H2 gas mixture
2 mm gap RPC with C2F5H gas mixture
10 gap (250 micron) double stack MRPCwith C2F4H2 gas mixture
knee of eff. plateau
knee of eff. plateau
knee of eff. plateau
Charge produced by through-going charged particle [pC]
Semiconductive glass
210mm*70mm*0.7mm
~1010.cm
Rate: 28 k Hz/cm2
Semiconductive ceramics
80mm*50mm*1mm
106 ~109.cm
GRPC activitiesHigh rate GRPCTsinghua University (Y.Wang)
Few small chambers will be tested with the SDHCALIn the next TB at cern.
DAC output (Vth)
Trigger
25 µs
PWR ON
HR2
4.7 mm
4.3m
mElectronics readout
3 thresholds with “independent” gain correctionNew PCBs are under design for a second M2
FSB0 scurves: HR1 /HR2 before and after gain correction
9% 5% 6.7% 1.4%
HR1 before cor.
HR1 after cor.
HR2 before cor.
HR2 after cor.
Qinj=100fC
Pedestal substracted
PCB connection : Assemble 2 X 3 PCBs on 1M2 Support
hardrocHoles
Readout electronicsDIFs (×120) ASUs
DAQ PC
DCC
Clock& Control
LDA
ODR
LDA
DCC
×10×9
:×14
:
DAQ
DHCAL DIFDHCAL DCC
PCB DESIGN
50 cm3
3.3
cm
1536 pads on Bottom Layer
DIF connector
ASU to ASU connector
ASU to ASU connector
Power and Gnd ConnectorASU to ASU on X axis
GND Connector ASU to ASU on Y axis
Y
X
HR1
HR24
GND Connector ASU to ASU on Y axis
Buffers(Other signals)
Buffers(Clocks)
Buried and Blind Vias (Same as the last PCB with 4 HR)
30 holes for M1 screws were distributed on the PCB for fixation on the absorber
T7 T7
1
2
3
1
2
3
weld
Via
0 ΩResistance
4
4 Pist
2 3
Schematic view of possible connections between two pcb
Electrical issue
4 PCB with 8X8 pads with the same structure of those used in the4-Chip ones are built to study the connection and its effect on the signal.
ER
i
Retrour de i
ER
i
Retrour de i
ER
i
Retrour de i
ER
i
Retrour de i
For low frequency the signal is not affected by the discontinuity
For high frequency the signal is affected by the discontinuity(an inductance of 1nH/cm)
The measurements we realized confirm the prediction and give an estimateof the number of discontinuities that we may allow for one detector plan.
Electronics readout status for M2 detector
• 8 PCB of 50X33.3 cm2 were conceived and produced• 8-layer, class 6 (buried vias)• 6 were equipped with hardroc1 (plastic packaging) 144 ASICs• PCB are connected 2 by 2 using zero resistor
DIF Slab 1 Slab 2
Electronics reqdout status for M2 detector
Problems found and fixed :
• Slow control and data readout failure: “Clock signal arriving before data signal after few ASICs”
buffers added (2/24 asics) critical line were adapted to avoid reflections
• DIF firmware failures state machines “latched” external trigger system correctly implemented
Data taking with cosmics started last week with one PCB-doubletIf ok we equip one 1M2
Hardroc 42 has been hit on channel 1Charge injected is 3.2pC (1.6V on 2pF)
1m2 GRPC chambers were tested with the small electronics board (4HR1)
PCB-doublets (3072 ch each) are tested independently
PCB-doublet on 1m2 are being tested
Fully equipped large detector to be soon tested in cosmic rays bench and in test beam at cern in June09
X(cm)Y(cm)
COSMICS
1 m2 GRPC
3-plan trigger
Slab #1
Slab #2
Slab #3
DIF #1
DIF #2
DIF #3
GRPC
Preparation for the 1M3 technological prototype
The aim is to come as close as possible to what we would like to have for ILC.
Technological prototype :40 planes of 1M2 :16mm s.steel absorber4mm s.steel support6mm GRPC
Important points:Semi-digital readout, mechanical structure, gas systemDAQ, event building, data storage.
g sense
Mechanical structure for the 1 m3
1 CNC machine of aprox 4x1 m2 working table. Accuracy of aprox 0.03 mm/m, with temperature compensation.
This is the machine that can be used to produce the plates for the HCAL prototype.
CIEMAT
Preparation for the 1M3 technological prototype
• Pions with different energies were simulated to better understand the containment• Analyses to exploit the three thresholds have started by having an idea of the energy/particles going in one pad• Work has started to develop algorithms for energy reconstruction using the 3 thresholds • Digitization is worked out.
ECAL DHCAL
100 GeV pions
1 GeV Muon:1Mip ~ 500eV
Assume Eion = 20eV1Mip ~ 25 ionization
G0, mean gain
For muon of 1 GeV
Conclusion
Digital hadronic calorimeters can be a powerful tool for physics achievement in the future ILC. They provides the granularity needed while keeping homogeneity and efficiency high
Still many efforts are needed to build a technological1m3 prototype and smart ideas to exploit it….