building a tracking calorimeter for the ILC

Valeria Bartsch

University College London

CALICE- french for chalice -

We are searching for the holy grail in energy resolution

Outline

ILC detectorLHC detectors LEP detectors

Energy Resolution

Particle Flow Algorithms

Dual Readout

Tests in testbeam

Consequence on DAQ design

A calorimeter for the ILC- comparison with the LHC -

LHC & ILC provide a complementary approach

• LHC pushes the energy frontier to 14TeV for proton-proton collisions (qq, qg, gg to 0.5-5TeV)

• ILC optimised for precision measurements at an energy range 0.1-1TeV for electron-positron collisions

Physics cases for LHC and ILC and their interplay very well studied

A calorimeter for the ILC- comparison with the LHC -

LHC: pp H + X ILC: e+e- H + Z

Electron-positron collider provide a cleaner environment than hadron colliders

A calorimeter for the ILC- comparison with LEP -

• LEP ran at 90-115GeV e+e- Z and e+e- W+W- physics processes dominate Lepton machine at low energies allow kinematic

constraints for mass reconstruction Energy resolution not vital

• ILC is planned to run at the 0.5-1TeV range Backgrounds dominate Kinematic fitting not possible due to Beamstrahlung and

final states with neutrinos

ILC depends critically on the detector performance

A calorimeter for the ILC- ILC machine -

• Using superconducting accelerating structures• Collision energy between 0.2-0.5(1.0) TEV• Integrated luminosity 500 fb-1 in the first 4 years• Radiation hardness does not dictate detector design

109 n cm-2 year-1 compared to 1014 n cm-2 year-1 at the innermost detectors of the LHC

Physics drives the detector design

A calorimeter for the ILC- physics at the ILC -

ILC physics:• Higgs sector• SUSY particle spectrum• SM particle …

Physics characterised by:• High multiplicity final states(6 - 8 jets)• Small cross sections

Detector optimised for multi-jet environmentE/E = 30%/√E

A calorimeter for the ILC- effect of energy resolution -

E/E = 30%/√E (0.5 * E/E of LEP)Energy resolution directly impacts sensitivity(equates to an increase in luminosity)

e.g. benchmark process: WW scattering important to distinguish between:e+e-WWqqqq from e+e-ZZ

A calorimeter for the ILC- new approaches to calorimetry -

• Particle Flow Algorithms– Approach of the CALICE collaboration – Proposed by 2 of the 3 detector concepts

• DREAM concept (also called dual readout)– Proposed by 1 of the 3 detector concepts

Outline

ILC detectorLHC detectors LEP detectors

Energy Resolution

Particle Flow Algorithms

Dual Readout

Tests in testbeam

Consequence on DAQ design

A calorimeter for the ILC- DREAM or dual readout approach -

• Uses scintillation & clear fibers

• Scintillating fibers respond to all charged particles

• Clear fibers detect e-/e+ Dual readout is able to

detect fluctuations in the energy resolution due to different response for em and hadronic part of showers

A calorimeter for the ILC- DREAM or dual readout approach -

EM shower energy correction improves energy resolution:

• Scintillator readout: 49%/√E• Cherenkov light: 86%/√E combined: 41%/√E

Can be further reduced: in bigger prototypes Measuring neutron depositions

Technology not yet advanced enough, however at high jet energies clearly a contender

Outline

ILC detectorLHC detectors LEP detectors

Energy Resolution

Particle Flow Algorithms

Dual Readout

Tests in testbeam

Consequence on DAQ design

A calorimeter for the ILC- Particle Flow Algorithms (PFA) -

Particles in jets Fraction of energy

Measured with Resolution [2]

Charged 65 % Tracker Negligible

Photons 25 % ECAL with 15%/√E 0.072 Ejet

Neutral Hadrons 10 % ECAL + HCAL with 50%/√E

0.162 Ejet

Confusion ≤ 0.042 (goal)

Traditional calorimetry limited by HCAL energy resolutionUse the information provided by the whole detector to improve the energy resolution

A calorimeter for the ILC- Particle Flow Algorithms (PFA)-

• Need to be able to match energy deposits and particle tracks

High granularity calorimeter supported by software

• Problem: in a multijet environment energy from the same particle can be double counted or energy deposits from different particles not properly separated

Gives rise to the confusion term Optimize lateral/longitudinal segmentation & software

A calorimeter for the ILC- Particle Flow Approach (PFA)-

Optimise the detector for Particle Flow:ECAL• Lateral segmentation

= Moliere radius = 1cm for Si/W ECAL• Longitudinal segmentation

= about 1 radiation length (in total 30 layers = 24X0)HCAL:• Lateral segmentation less clear (about 1cm)• Longitudinal size limited by constraints that HCAL is

inside the magnetic coil= 4-5 interaction lengths

A calorimeter for the ILC- testing the PFA approach -

• Behaviour in test beams needs to be tested MC predictions can be related to real data PFA predictions can be tested new methods can be developed

• several options for the detector technology possible these options need to be investigated in testbeams

• High number of readout channels -> more pressure on DAQ a reliable DAQ system needs to be tested

CALICE collaboration’s goal to test feasibility of PFA

Technical prototypes

Can be only partially equippedAppropriate shapes (wedges) for ILC detectors

All bells and whistles (cooling, integrated supplies…)

To provide a basis for choosinga calorimeter technology

for the ILC detectors

To measure electromagnetic andhadronic showers with

unprecedented granularity

To design, build and testILC calorimeter prototypes

To advance calorimetertechnologies and our

understanding of calorimetryin general

Physics prototypes

Various technologies (silicon, scintillator, gas) Large cubes (1 m3 HCALs) Not necessarily optimized for an ILC calorimeter

A calorimeter for the ILC- goals of the CALICE collaboration -

Outline

ILC detectorLHC detectors LEP detectors

Energy Resolution

Particle Flow Algorithms

Dual Readout

Tests in testbeam

Consequence on DAQ design

• 0.5cmx0.5cm segmentation results in 100M channels with little room for electronics or cooling

• Triggerless

~250 GB of raw data per bunch train need to be handled

A calorimeter for the ILC- concept for the DAQ -

“Final” Detector

ECAL

HCAL

1st ECAL Module(module 0)

ECAL Prototype

A calorimeter for the ILC- time structure -

• Interesting time structure, long gaps between bunch trains

• In the order of 1000 bunch crossings / bunch train Time structure heavily used in the design of the data

acquisition system all electronics will be powercycled to decrease

cooling need readout of the system between bunch trains

A calorimeter for the ILC- Very Front End Electronics -

ASICS• Must share readout resource

(daisy chain)• Bunch rate too high for

instantaneous data transfer.• Too much chip resource to

store all eventsSO:• ‘Auto-trigger’ – store only data

over-threshold with pad id + (bunch-number)

• <5kByte / bunch-train/ASIC

ECAL Module-0 (reduced-Z octant)

L = 150 cm

ASIC

(>100 in total!)

Typical layer2m2

2000 tiles

38 layers80000 tiles

Instrument one tower (e.m. shower size)

+ 1 layer (few 1000 tiles)

• 3 different detector types: ECAL, AHCAL, DHCAL• study of full scale technological solutions• prototype expected end of 2009

Detector Interface Boards

A calorimeter for the ILC- EUDET prototype -

LDA

LDAHost PC

PC

Ie

ODR

Host PC

PC

Ie

ODR

DetectorUnit

DIF

C&C

DetectorUnit

DIF

DetectorUnit

DIF

DetectorUnit

DIF

Storage

1-3Gb Fibre50-150 Mbps HDMI

cabling

10-100m0.1-1m

Det

ecto

r

Co

un

tin

g R

oo

m

Detector Unit: ASICs

DIF: Detector InterFace connects Generic DAQ and services

LDA: Link/Data Aggregator – fanout/in DIFs and drives link to ODR

ODR: Off Detector Receiver – PC interface for system.

CCC: Clock & Control Card: Fanout to ODRs (or LDAs)

CONTROL PC: DOOCS GUI (run-control)

A calorimeter for the ILC- DAQ architecture-

it is a very important step toward a full detector design

A calorimeter for the ILC- DAQ architecture-

Outline

ILC detectorLHC detectors LEP detectors

Energy Resolution

Particle Flow Algorithms

Dual Readout

Tests in testbeam

Consequence on DAQ design

A calorimeter for the ILC- strategy for the testbeam analysis -

Build up the analysis in the ECAL and HCAL:• Calibration • Detector stability• Energy resolution• Longitudinal + lateral profile• Comparison of distributions between hadrons and

GEANT4 simulations• Detector optimisation

Before looking into PFAs check the fundamentals

DESY electrons 2006 Silicon-ECAL Scintillator ECAL Scintillator HCAL TCMT

CERN electrons and pions 2006 and 2007 Silicon-ECAL Scintillator HCAL TCMT (complete)

FNAL electrons and pions 2008 Silicon-ECAL Scintillator ECAL Scintillator HCAL TCMT (complete)………

CERN 200714 TB

A calorimeter for the ILC- main CALICE test beams-

A calorimeter for the ILC- CALICE Test Beam Activities -

UK

Physics prototype•30 ECAL layers•30 HCAL layers•TCMT

TCMT

HCAL

ECAL

-SiW Tungsten Ecal with up to 9400 cells operated successfully during testbeam campaigns 2006 to 2008 -Stable operation uniform response to MIPs, robust calibration -only 1.4/mill dead cells

As expected, a PIN diode silicon detector is stable

A calorimeter for the ILC- stability of detectors (e.g. ECAL)-

32

Need to take geometrical acceptance into account in analysis

E/GeVE/GeV

22

A calorimeter for the ILC- dead zones (e.g. ECAL)-

33

• correction restores homogenous response• energy loss due to acceptance limits• not fully recovered• important issue for future R&D

requires close collaboration with suppliers

A calorimeter for the ILC- dead zones (e.g. ECAL)-

Resolution with electrons

A calorimeter for the ILC- linearity & resolution (e.g. ECAL) -

Linearity with electrons

• linearity better than 1%• energy resolution without PFA as expected

Transverse shower profile

• Moliere radius RM contains • 90% of EM shower energy• independently of energy• RM (W) = 9 mm

A calorimeter for the ILC- shower profiles (e.g. ECAL) -

Longitudinal shower profile

• MC describes data very well• leakage energy, shower max can be extracted

CALICE preliminary

A calorimeter for the ILC- leakage energy of the ECAL -

CALICE preliminary

For the correct extraction of the leakage energy:• Low energy particles in showers interact differently Sampling fraction depending on the age of the

shower Need to simulate energy deposition in active and

passive layer to extract sampling fraction f:

f = Epas/ Etot

CALICE preliminary

37

A calorimeter for the ILC- hadrons: resolution and long. Profile -

• energy resolution without using PFA• this kind of measurements allows comparisons with GEANT4• more comparisons especially of the lateral profile are underway

• pion sample with single events and large spread over detector front face• possible to select events with given distance• and overlay offline two showersadvantage energy of single pion is known

A calorimeter for the ILC- overlay of showers -

select events according to distance

and overlay

A calorimeter for the ILC- shower separation -

∫∫

∞+

∞−

+

−=1calo

3ó

3ó cluster

E

Eeff

efficiency of shower separation:CALICE preliminary

MC studies for AHCAL geometry optimization MC 1 charge + 1 neutral hadron simulated data 2 charged pions MC with HCAL onlydata contained showers in AHCAL but ECAL used as tracker

3x3x1

qualitative good agreement

CALICE preliminary

MC

Only distance <10cm probed

by data

A calorimeter for the ILC- shower separation -

A calorimeter for the ILC- summary & outlook -

• ILC calorimetry can stretch energy resolution to the limit

• Particle Flow concept adequate for ILC• Consequence on the calorimeter design: high

granularity• CALICE collaboration’s goal is to invest R&D to test

PFA idea

A calorimeter for the ILC- outlook -

• Test beams (checks alternative technologies, GEANT4 models, PFAs)– Performances well understood– Publications started

• Technological prototypes test technical realisation of the needed functionality (including a new DAQ system)– Prototype built for 2010– Ready for a module zero 2013

A calorimeter for the ILC- spare slides -

• Utilise off the shelf technology – Minimise cost, leverage industrial knowledge– Use standard networking chipsets and protocols,

FPGAs etc.• Design for Scalability• Make it as generic as possible

– exception: detector interface to several subdetectors• Act as a catalyst to use commodity hardware

PC-based receiver card is a key component in the generic DAQ design

A calorimeter for the ILC- concept for the DAQ -

Detector Concept

Optimized for PFA

Compensating

Calorimetry

(hardware)

SiD Yes No

ILD Yes No

4th No Yes

CALICE Projects

ECALs Silicon - Tungsten

MAPS - Tungsten

Scintillator - Lead / Tungsten

HCALs Scintillator - Steel

RPCs - Steel

GEMs- Steel

MicroMegas - Steel

TCMTs* Scintillator - Steel

A calorimeter for the ILC- CALICE & the ILC detector concepts-

A calorimeter for the ILC- goal for the energy resolution -

• Energy resolution should be in the order of the natural width of the bosons:

m/m 2.5/91 2.1/80.3 0.03E/E 0.03

• Typical jet energies at the ILC: 100-300 GeVE/E 0.03/√E

Traditional calorimetry limited by HCAL resolution of >50% /√E new approach needed