Report from the the CALICE Collaboration 164 Physicists 26 Institutes 9 Countries 3 Regions José Repond Argonne National Laboratory CA lorimeter for the LI near C ollider with E lectrons A calorimeter optimized for the Energy Flow measurement of multi-jet final states at the Future Linear Collider running at a center-of-mass energy 90 GeV and 1 TeV

Hadronic Calorimeter Analog readout – ‘Tile HCAL’ Germany, Czech, Russia… Digital readout – ‘DHCAL’ I Gas Electron Multipliers (GEMs) Texas at Arlington II Resistive Plate Chambers (RPCs) Russia, USA (ANL, Boston, Chicago, FNAL) III Scintillator Northern Illinois IV Short Drift Tubes (SDTs) Protvino Electromagnetic Calorimeter Silicon – Tungsten France, UK + friends Silicon – Scintillator ‘LCCAL’ Italy Not part of CALICE Will report on these Others covered by individual talks at this workshop

CALICE ECAL Fine granularity tracking calorimeter Silicon – Tungsten sandwich 1 x 1 cm 2 pads 40 layers Simulated energy resolution Prototype for test beams 30 layers Active area 18 x 18 cm channels Goal: first tests in 2004 Structure 1.4 (1.4mm of W plates) Structure 2.8 (2×1.4mm of W plates) Structure 4.6 (3×1.4mm of W plates) ACTIVE ZONE Metal insert Detector slabs 60 mm Si Wafer with 6×6 pads 10×10 mm 2

Front End electronics (Cfi / W) structure type H Silicon wafer Shielding PCB Al. Shielding PCB (multi-layers) (  2.4 mm ) Silicon wafer (0.525 mm) Tungsten (1.4 mm, 2×1.4 or 3×1.4 mm) 8.5 mm Composite structure (0.15 mm / layer) Transverse view Detector slab PCB 14 layers Thickness 2.4 mm

Chips Wafer PCB board PCB, Wafers, Chips…

Front-end electronics: ASIC Second version being developed…. FLC_PHY1 FLC_PHY2 Preamp  16 gains (0.2, 0.4, 0.8, 1.6pFswitchable) Lowernoise (inputtrans improved) Shaper  bigain differential track&hold  differential Preamp  1 gain (1.5pF) Lownoise (2200e - ) Shaper  Mono gain unipolar track&hold  Unipolar Pin- compatibility Amp OPA MUX out Gain=1 MUX out Gain=10 1channel Measurements on FLC_PHY1 Linearity 0.3% Dynamic range 3.5 pC Noise 2200 e - Pedestal dispersion σ=5mV Satisfactory

Rear-end electronics Developed in the UK Use of CMS Back end

Schedule Mechanical structure Tungsten plates by end of 2003 Assembly in early 2004 FE ASICs FLC_PHY2 tested by September Choice of ASIC Production completed by end of 2003 FE PCB boards Built by February 2004 RE boards Fabrication and assembly in Mar’03 Prototype in beam Cosmic rays first half of 2004 Electrons by mid 2004 Hadrons in 2005

LCCAL 45 layers 25 x 25 x 0.3 cm 3 Lead 5 x 5 x 0.3 cm 3 Scintillator 3 layers of Silicon 1 x 1 cm 2 pads at 2, 6, 12 X 0 Not part of CALICE Collaboration Como, LN Frascati, Padova, Trieste Concept Lead/scintillator plus silicon

EEEE Extensive Tests in Frascati Test Beam Electrons and positrons 50 – 850 MeV Energy selection 1 % Up to 10 3 electrons/s Energy resolution as expected N pe > 5.1/layer → p.e. statistics negligible Uniformity of light collection at 10 – 20 % level Recently inserted Silicon pads E (MeV)

Conclusions and Perspectives LCCAL prototype Almost fully working More Silicon pads are being constructed Third Silicon layer will be fully equipped Test run at Frascati Underway Energy response and resolution as expected Merging Silicon and Energy information: understand multiple hits (>1 e - ) Two test beams at Higher Energy in preparation PS and SPS (in 2003) Monte Carlo Simulation Studies of hybrid technique to be initiated

Hadron Calorimeter HCAL located inside 4T coil Thickness 4.5 λ … Barrel 6.2 λ … Endcap Cell structure Iron 20 mm Active medium 6.5 – 10.0 mm TESLA TDR Two options a) Analog hadron calorimeter with scintillator b) Digital hadron calorimeter with …

Analog HCAL Scintillator tiles Area 5 x 5 → 25 x 25 cm 2 Thickness 5 mm Longitudinal segmentation 9 … Barrel 12 … Endcap Strong R&D program Tests of different plastic scintillator Fiber routing optimization Selection of wavelength-shifting fibers Coupling of WLS-fibres to scintillator Clear fiber selection Connection of WLS and clear fibres Photodetectors

A few examples… Scintillator PolyVinylToluene based → more expensive BC-408, BC-404… PolyStyrene based → less light SCSN-81, Kuraray, BASF-143… WLS Fiber Routing Stress on fiber → ageing?

WLS Fiber Diameter 1 mm, double clad BC-91A BC-92 Y11(500ppm) … Treatment of fiber end Polishing End reflector Treatment direction Finer sandpaper

Silicon – Photomultipliers SiPMs R&D at MEPHI (Moscow) together with PULSAR (Russian Industry) 2 ns 2 mV Overall size 1.5 x 1.5 mm 2 Sensitive area 1 x 1 mm 2 Gain 2 ∙10 6 at U bias ~ 50 V Number of pixels 576 → 1000 Recovery time ~100ns

4 – 8 photo-electrons 576 pixels U bias = 53 – 55 V 10 photo-electrons 576 pixels U bias = 54 V 15 photo-electrons 1000 pixels SiPM mounted on tile With threshold at ~ 20 photo-electrons Dark rate ~ 2 Hz MIP detection efficiency ~ 97.5%

Minical Array Purpose Cosmic rays starting in August Light Yield Uniformity of response Calibration with MIPs Test of different photo-detectors Long term ageing effects LED monitoring Stability Dynamic range Electron beam Energy resolution Constant term Linearity Stack 27 layers of 9 tiles 5 x 5 x 0.5 cm 3 scintillator APDs 3 tiles/APD MA-PMs 3 tiles/pixel SiPMs 1 tile/SiPM beam

1. Enough LY from TFS (~200 photons at photodetector) 2. APD’s and SI-PMs are the photodetectors which do the task 3. Preamplifiers with low noise are essential (MIP-noise separation,calibration) 4. Minical test to establish calibration precision in summer 5. Now design of prototype boards for APD and Si-PMs (DUBNA) 6. Photodetectors, large quantity to order in summer: 1000 APDs or ~ 5000 Si-PMs or both types in relevant quantities e.g. ~250/ Prototype stack (1m 3 ) will be build in summer 8. Assembly of PT-stack with TFS starts in Jan Spring 2004 is used to set up and calibrate all channels with cosmics. Slide by V Korbel shown at Amsterdam Meeting Outlook

DHCAL: Resistive Plate Chambers - RPCs Only Russian effort (Protvino) for US effort see separate talk Developed RPCs Single gap of 1.2, 1.6 or 2.0 mm Ω∙cm window glass as resistive plates Tests with 16 pads of 1 x 1 cm 2 Thickness 4.4 mm (without FEE) Gas mixtures Avalanche mode: TetraFluoroEthane : IB : SF 6 = 95 – 98 : 5 : 5 – 2 % Streamer mode : TetraFluoroEthane : IB : Ar/N 2 = 80 : 10 : 10 % Tests with Protvino test beam

Tests in avalanche mode Efficiency and pad multiplicity versus High Voltage To give a few examples… Tests with different gases and thresholds Best results for HV = 8.2 kV Threshold = 2.2 mV Efficiency ~ 99% Multiplicity ~ 1.4

Efficiency versus rate for avalanche and streamer mode Pad multiplicity versus charge for different anode thicknesses Noise rate versus High Voltage Maximum rate Streamer mode Hz/cm 2 Avalanche mode ~ 300 Hz/cm 2 The thinner the anode the smaller the multiplicity At optimal operating point ~0.5 Hz/cm 2

Comparison of operation modes As an example for 1.2 mm gas gap… Favored AvalancheStreamer Gas mixtureTFE:IB:SF 6 = 93:5:2TFE:IB:Ar = 85:10:5 HV working point8.4 kV7.0 kV Induced charge3.4 pC300 pC Threshold on 50 Ω1 – 2 mV50 – 200 mV Efficiency> 99 %~ 95 % σ q /Q~ 1~ 0.6 Pad multiplicity – 1.5 Noise~0.5 Hz/cm 2 ~0.1 Hz/cm 2 Rate capability300 Hz/cm 2 4 – 5 Hz/cm 2 Ageing effectsNoneObserved

Plans December 2003 Beam tests with 20 layer ‘electromagnetic’ calorimeter 64 pads per layer June 2004 Ready for production and assembly of 1 m 3 prototype

DHCAL: Short Drift Tubes - STDs Cell size 1 cm 2 x 3 mm Gas IB : Ar : TFE = 80 : 10 : 10 Efficiency and Multiplicity as function of High Voltage Currently using flammable gas exploring performance with other mixtures Being developed in Protvino…

DHCAL: Readout schemes Real challenge…. 1 m 3 prototype: 400,000 channels! IHEP ProtvinoConditioning + FPGA + Serialiser JINR DubnaComparators + FPGA + VME US groupsCustom FE ASIC + concentrator + collector KoreaTesting entire chain of comparators and digital processing Imperial College London Adapting ECAL readout scheme to A/DHCAL

Readout at Protvino Conceptual design Readout for 64 channels I Conditioning (analog) II FPGA (digital) III Serializer (readout of several FPGA)

Readout at Dubna Price ( $)Prototype5000 chThr. JINR Apl.+ CPLD READYEnd of mv Comp+ Sh. Reg CMS ampl. US + CPLD READYNov US ? 2-5 mv CMS amp.Bel + CPLD 0.5?? 0.04 READYNov ? Minsk ? 3-6 mv Bel.0.5?????3-6 mv

HCAL: Mechanical Structure of 1 m 3 Prototype Structure 40 Layers Each 1 m 2 20 mm steel plates Weighs 6 tons! Issues Material of absorber Steel Stainless steel Tolerances on thickness, flatness Active gap Adjustable width Tolerances Support plates, e.g. 2 mm steel Logistics Tests in magnetic field, what B 1 or 2 stacks Who builds it

DHCAL meeting at DESY on June 30, 2003 CALICE meeting in Amsterdam on 31-March-2003 ECFA/DESY LC workshop in Amsterdam, April 1 – 4, DHCAL meeting in Paris on 28-February-2003 More information and upcoming meetings… A/DHCAL meeting at DESY around October 24, 2003