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 detectorsLEP 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 GeV  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 (1.0) TEV Integrated luminosity 500 fb -1 in the first 4 years Radiation hardness does not dictate detector design 10 9 n cm -2 year -1 compared to 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 environment  E /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 -  WW  qqqq 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 detectorsLEP 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 detectorsLEP 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 jetsFraction of energy Measured with Resolution [  2 ] Charged65 %TrackerNegligible Photons25 %ECAL with 15%/√E E jet Neutral Hadrons10 %ECAL + HCAL with 50%/√E E jet Confusion≤ (goal) Traditional calorimetry limited by HCAL energy resolution  Use 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 equipped Appropriate shapes (wedges) for ILC detectors All bells and whistles (cooling, integrated supplies…) To provide a basis for choosing a calorimeter technology for the ILC detectors To measure electromagnetic and hadronic showers with unprecedented granularity To design, build and test ILC calorimeter prototypes To advance calorimeter technologies and our understanding of calorimetry in general Physics prototypes Various technologies (silicon, scintillator, gas) Large cubes (1 m 3 HCALs) Not necessarily optimized for an ILC calorimeter A calorimeter for the ILC - goals of the CALICE collaboration -

Outline ILC detectorLHC detectorsLEP 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 1 st 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 events SO: ‘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 layer 2m tiles 38 layers 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 Host PC PCIe ODR Host PC PCIe ODR Detector Unit DIF C&C Detector Unit DIF Detector Unit DIF Detector Unit DIF Storage 1-3Gb Fibre Mbps HDMI cabling m 0.1-1m Detector Counting Room 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 detectorsLEP 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 HCALTCMT CERN electrons and pions 2006 and 2007 Silicon-ECALScintillator HCAL TCMT (complete) FNAL electrons and pions 2008 Silicon-ECAL Scintillator ECAL Scintillator HCAL TCMT (complete) ……… CERN 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 HCAL ECAL

-SiW Tungsten Ecal with up to 9400 cells operated successfully during testbeam campaigns 2006 to 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/GeV 2 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 R M contains 90% of EM shower energy independently of energy R M (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 = E pas / E tot 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 showers advantage  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 - 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 only  data 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) SiDYesNo ILDYesNo 4 th NoYes CALICE Projects ECALsSilicon - Tungsten MAPS - Tungsten Scintillator - Lead / Tungsten HCALsScintillator - 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  0.03  E /E  0.03 Typical jet energies at the ILC: GeV  E /E  0.03/√E Traditional calorimetry limited by HCAL resolution of >50% /√E  new approach needed