Experimental Challenges and
Techniques for Future Accelerators
Joachim Mnich
DESY
XI ICFA School on Instrumentationin Elementary Particle Physics
San Carlos de Bariloche, Argentina11 - 22 January 2010
Joachim Mnich | Detectors at Future Colliders | ICFA Seminar Bariloche January 2010 | Page 2
Outline
> Lecture 1Future particle physics at the energy frontier: case for a Linear Collider
Linear Collider Concepts
Experimental Challenges
> Lecture 2Detector Concepts
R&D for detector components
Vertex detector
Tracking detectors
Calorimeters
Joachim Mnich | Detectors at Future Colliders | ICFA Seminar Bariloche January 2010 | Page 3
Detector ConceptsFour detector concepts (have been) investigated
GLD (Global Large Detector)LDC (Large Detector Concept)SiD (Silicon Detector)4th concept
Summer 2006: Detector Outline Documents (DOD)evolving documents, detailed description
Summer 2007: Reference Design Reports (RDR)comprehensive detector descriptions, along with machine RDR
Prepared by international study groupsO(100 - 300) authors per detector concept
Merged into one concept:(ILD) International Large Detector
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Detector ConceptsGLD- TPC tracking
large radius- particle flow calorimeter- 3 Tesla solenoid- scint. fibre µ detector
LDC- TPC tracking
smaller radius- particle flow calorimeter- 4 Tesla solenoid- µ detection: RPC or others
Both concepts are rather similar have merged into one (ILD)
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Detector Concepts
SiD- silicon tracking- smaller radius- high field solenoid (5 Tesla)- scint. fibre / RPC µ detector
Silicon tracker
6.45 m
6.45 m
Magnet- high field- but smaller volume
• CMS
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Detector Concepts4th concept- gaseous tracking- multiple readout calorimeter- iron-free magnet, dual solenoid- muon spectrometer (drift tubes)
Dual solenoid- iron return yoke replaced
by second barrel coiland endcap coils Average field
seen by µ:
<B> ≈ 1.5 T<Bl> ≈ 3 Tm
B
coil
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Detector Concept and R&D effortsR&D efforts for key detector elementsOverlap with detector concepts:
ILD SID 4th concept
Detector R&D collaborations
Vertex X X X LCFI
Tracking
Calorimetry:
- TPC X X LCTPC
- Silicon * X * SILC
- Particle Flow X X CALICE
- Multiple Readout X- Forward region X X X FCAL
* silicon forward and auxiliary tracking also relevant for other concepts
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ILC International Detector Advisory Group
September 2009: recommendations by „wise men“on validation of concepts
ILD and SiD concepts should continue to develop4th not validatedbut R&D on dual readout calorimetery should continue ( CLIC)
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Vertex DetectorKey issuses:
measure impact parameter for each trackspace point resolution < 5 µmsmallest possible inner radius ri ≈ 15 mmtransparency: ≈ 0.1% X0 per layer
= 100 µm of siliconstand alone tracking capabilityfull coverage |cos Θ| < 0.98modest power consumption < 100 W
Five layers of pixel detectorsplus forward disks
pixel size O(20×20 µm2) 109 channels
Note: wrt. LHC pixel detectors1/5 ri1/30 pixel size1/30 thickness
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Vertex DetectorCritical issue is readout speed:Inner layer can afford O(1) hit per mm2 (pattern recognition)
once per bunch = 300 ns per frame too fastonce per train ≈ 100 hits/mm2 too slow20 times per train ≈ 5 hits/mm2 might work50 µs per frame of 109 pixels!
→ readout during bunch train (20 times)or store data on chip and readout in between trainse.g. ISIS: In-situ Storage Image Sensor
Many different (sensor)-technologies under studyCPCCD, MAPS, DEPFET, CAPS/FAPS, SOI/3-D, SCCD, FPCCD, Chronopixel, ISIS, …→ Linear Collider Flavour Identification (LCFI) R&D collaborationBelow a few examplesNote: many R&D issues independent of Si-technology(mechanics, cooling, …)
Joachim Mnich | Detectors at Future Colliders | ICFA Seminar Bariloche January 2010 | Page 11
CP CCDCCD
create signal in 20 µm active layeretching of bulk material to keeptotal thickness ≤ 60 μmlow power consumptionbut very slow
→ apply column parallel (CP) readout
p(Epi)
p+(bulk)
p/p+(edge)
Depletionedge
n layer
Particle trajectory
~20µmactive
x
x
xxxx
x
CCD classic CP CCD
Second generation CP CCDdesigned to reach 50 MHz operation
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MAPS and DEPFETCMOS Monolithic Active Pixel detectors
standard CMOS wafer integratingall functionsno bonding between sensor and electronics
e.g. Mimosa chip
DEPFET: DEPleted Field Effect Transistor
fully depleted sensor withintegrated pre-amplifierlow power and low noise
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Silicon TrackingThe SiD tracker:
5 barrel layersri = 20 cm ro = 125 cm10 cm segmentation in zshort sensorsmeasure phi only
endcap disks5 double disk per sidemeasure r and phi
critical issue:material budget(support, cooling, readout)goal: 0.8% X0 per layer
10% X0
Material budget completetracking system
beam pipe
+ VTX
+ main tracker
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Materials: from Concept to Reality
The detector TDR 1996
... and the reality 10 years later
0.7 X0
CMS
1.4 X0
1.4 X0CMS
CMSCMS
ATLASATLAS
Major difference / advance to LHC detectors is needed:
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TPC Tracking
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TPC Tracking
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Time Projection ChamberGLD, LDC and 4th: high resolution TPC as main tracker
3 – 4 m diameter≈ 4.5 m lengthlow mass field cage
3%X0 barrel< 30% X0 endcap
≈ 200 points/track≈ 100 µm single point res.
→ Δ(1/pT) = 10-4 /GeV(10 times better than LEP!)
Complemented by Forward Trackingendcap between TPC and ECALSi strip, straw tube, GEM-based, …are considered
TPC development performed inLCTPC collaboration
endcap tracker
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Time Projection ChamberNew concept for gas amplicationat end flanges:Replace proportional wires byMicro Pattern Gas Detectors (MPGD)
GEM or MicroMegasfiner dimensionstwo-dimensional symmetry→ no E×B effectsonly fast electron signalintrinsic suppression of ion backdrift
inducecharge
Pads
sense/fieldwires
gatinggrid
track
driftingchargeWires
track
charge
GEMfoil
pad
dritfting
GEM
Micromesh
Insulatingsubstrate
Pillar
Pad planeMultiplicationregion
GEM µMegas
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Time Projection ChamberLow mass fieldcage
large prototype underconstructionusing composite material
Electronicsfew 106 channels on endplate (ILD)low power to avoid cooling
two development paths:- FADC based on ALICE ALTRO chip- and TDC chips
≈ 1% X0
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Time Projection ChamberPrinciple of MPGD based TPC established
Single point resolution O(100 µm)achieved in small scale prototypes
Large ILC TPC prototype
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TPC versus Silicon TrackingTPC
200 space points (3-dim) → continuous tracking, pattern recognitionlow mass easy to achieve (barrel)
Silicon trackingbetter single point resolutionfast detector (bunch identification)
TPC Si tracking
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Silicon TPC Readout
Combine MPGD withpixel readout chips2-d readout with- Medipix2 0.25 µm CMOS- 256×256 pixel- 55 ×55 µm2
Medipix (2-d)→ TimePix (3- d)50 - 150 MHz clock to all pixel1st version under test
Will eventually lead to TPC diagnostic modulecluster countingto improve dE/dx
(Micromegas) (GEM)
TimePix layout TimePix + µMegas
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Calorimetry
The Particle Flow Algortihm (PFA)consider 5 GeV particles in a jet
EM
Neutral Hadrons
Charged Hadrons
5 GeV
tracker
Δp=0.002GeV
ECAL
ΔE=0.2GeV (ΔE=1.1GeV)
HCAL
error5 GeV electron: 0.002 GeV
photon: 0.2 GeVneutron: 1.1 GeV
Average visible energy in a jet≈ 60% charged particles≈ 30% photons≈ 10% neutral hadrons
but be aware of large jet-by-jetfluctuations of the composition
Joachim Mnich | Detectors at Future Colliders | ICFA Seminar Bariloche January 2010 | Page 24
CalorimetryThe paradigm of Particle Flow Algortihm (PFA)for optimum jet energy resolution:
try to reconstruct every particlemeasure charged particles in trackermeasure photons in ECALmeasure neutral hadrons in ECAL+HCALuse tracker + calorimeters to tell charged from neutral
Jet energy resolutionσ = σcharged⊕ σphotons ⊕ σneutral ⊕ σconfusion
confusion term arises frommisassignment, double counting, overlapping clusters, …minimizing confusion term requires highly granular calorimeterboth ECAL and HCAL
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Joachim Mnich | Detectors at Future Colliders | ICFA Seminar Bariloche January 2010 | Page 26
CalorimetryCALICE collaboration (Calorimeter for the Linear Collider Experiment)> 30 institutes from > 10 countries
performs R&D effort to validate the concept and designcalorimeters for ILC experiments
ILD, SID conceptsbased on PFA calorimeters
ECAL:SiW calorimeter23 X0 depth0.6 X0 – 1.2 X0 long. segmentation5×5 mm2 cellselectronics integrated in detector
Alternative: W + Scintillating strips
ECAL slabFE ASICPCB boardSi pads
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CalorimetryHCAL: 2 options under consideration
Analogue Scintillator Tile calorimetermoderately segmented 3×3 cm2
use SiPM for photo detection
Gaseous Digital HCALfiner segmentation 1×1 cm2
binary cell readoutbased on RPC, GEM or µMegasdetectors
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CalorimeterCALICE Testbeam at CERN
ECAL
HCAL
TCMT
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CalorimeterCALICE Testbeam at CERN
CALICE prototype now at FNAL
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> Use of calorimeter testProve technologies
Validate Monte Carlo
Develop reconstruction algorithms
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CalorimeterSimulation of an ILC event
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Dual Readout Calorimeter4th concept
calorimetry based on dual/triple readout approachcomplementary measurements of showers to reduce fluctuations
Fluctuations of localenergy deposits
Fluctuations in electromagnetic fractionof shower energy
Binding energy lossesfrom nuclear break-up
Fine spatial samplingwith SciFi every 2 mm
clear fibres measure onlyEM component by Cerenkovlight of electrons(Eth = 0.25 MeV)
try to measure MeV neutroncomponent of shower(history or Li/B loaded fibres)
like SPACAL (H1)
like HF (CMS)
triple readout
Dual Readout Module (DREAM) in testbeam at CERN
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A different approach: Dual Readout Calorimeter
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DREAM Test module
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Dual Readout CalorimeterDREAM testbeam:- measure each shower twice
200 GeV π− beam at CERN
raw data
usingC and S
incl. leakagecorrection(using EB)
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Forward CalorimetryForward calorimeters needed
LumCal: precise luminosity measurementprecision < 10-3, i.e. comparable to LEP or better
BeamCal: beam diagnostics & luminosity optimisation
LumiCal
BeamCal
TPC
ECAL
HCAL
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BeamCalChallenges:
≈ 15000 e+e− pairs per BXin MeV range, extending to GeVtotal deposit O(10 TeV)/BX≈ 10 MGy yearly rad. dose
identification of singlehigh energy electronsto veto two-photon bkgd.
Requires:rad. hard sensors (diamond)high linearity & dynamic rangefast readout (300 ns BX interval)compactness and granularity
Energy deposit per BX:
Electron ID efficiency:
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Conclusion & Outlook
Linear Collider is the next big project in particle physicsILC: 500 → 1000 GeV supraconducting technologyCLIC: → 3000 GeV two-beam acceleration
Ideally complements LHC discoveries by precision measurements
Requires detectors with unprecedented performanceschallenges different than at the LHCprecision is the main issue
2 detector concepts under developmentR&D on detector technologies
candidate technologiesidentified & verified in small scale experiments
Many questions still to be answered
Simulated ee → ZZ